This may be hard to visualize based on the description but the illustration above shows the orientation of the two crossing ligaments effectively. The anterior/cranial cruciate ligament prevents the tibia from slipping forward out from under the femur.

The key to the diagnosis of the ruptured cruciate ligament is the demonstration of an abnormal knee motion called a drawer sign. It is not possible for a normal knee to show this sign.

The Drawer Sign

If the rupture occurred some time ago, there will be swelling on side of the knee joint that faces the other leg. This is called a medial buttress and is a sign that arthritis is well along.

It is not unusual for animals to be tense or frightened at the vet’s office. Tense muscles can temporarily stabilize the knee, preventing your veterinarian from being able to try the drawer sign during an examination. Often, sedation is needed to get a good evaluation of the knee. This is especially true with larger dogs. Eliciting a drawer sign can be difficult if the ligament is only partially ruptured so a second opinion may be a good idea if the initial examination is inconclusive.

Since arthritis can set in relatively quickly after a cruciate ligament rupture, radiographs to assess arthritis are helpful. Another reason for radiographs is that occasionally when the cruciate ligament tears, a piece of bone where the ligament attaches to the tibia breaks off as well. This will require surgical repair and the surgeon will need to know about it before beginning surgery. Arthritis present prior to surgery limits the extent of the recovery after surgery though surgery is still needed to slow or even curtail further arthritis development.

How Rupture Happens

Several clinical pictures are seen with ruptured cruciate ligaments. One is a young athletic dog playing roughly who takes a bad step and injures the knee. This is usually a sudden lameness in a young large-breed dog.

A recent study identified the following breeds as being particularly at risk for this phenomenon: Labrador retriever, Golden retriever, Rottweiler, Neapolitan mastiff, Newfoundland, Akita, St. Bernard, Chesapeake Bay retriever, and American Staffordshire terrier.

On the other hand, an older large dog, especially if overweight, can have weakened ligaments and slowly stretch or partially tear them. A partial rupture may be detected or the problem may not become apparent until the ligament breaks completely. In this type of patient, stepping down off the bed or a small jump can be all it takes to break the ligament. The lameness may be acute but have features of more chronic joint disease or the lameness may simply be a more gradual/chronic problem.

Larger, overweight dogs that rupture one cruciate ligament frequently rupture the other one within a year’s time.

An owner should be prepared for another surgery in this time frame.

The cranial cruciate rupture is not limited to large breed dogs. Small dogs can certainly rupture their ligaments as well and, while arthritis is slower to set in when the patient is not as heavy, there is an association with cruciate rupture and medial luxating patella that is very common in small breed dogs. With the patellar luxation, the kneecap flips in and out of the patellar groove. If the condition is relatively mild, it may not require surgical correction but it does stress the cranial cruciate ligament and can predispose it to rupture and need to correct both conditions surgically.

What Happens if the Cruciate Rupture is Not Surgically Repaired

In one study, a group of dogs was studied for 6 months after cruciate rupture. At the end of 6 months, 85% of dogs less than 30 pounds of body weight had regained near normal or improved function while only 19% of dogs over 30 pounds had regained near normal function. Both groups of dogs required at least 4 months to show maximum improvement.

What Happens in Surgical Repair?

There are three different surgical repair techniques commonly used today. Every surgeon will have their own preference for which technique is best for a given patient’s situation.

Extracapsular Repair

This procedure represents the traditional surgical repair for the cruciate rupture. It can be performed without specialized equipment and is far less invasive than the newer procedures described below. First, the knee joint is opened and inspected. The torn or partly torn cruciate ligament is removed. Any bone spurs of significant size are bitten away with an instrument called a rongeur. If the meniscus is torn, the damaged portion is removed. A large, strong suture is passed around the fabella behind the knee and through a hole drilled in the front of the tibia. This tightens the joint to prevent drawer motion, effectively taking over the job of the cruciate ligament.

• The suture placed will break 2 to 12 months after surgery and the dog’s own healed tissue will hold the knee.

Tibial Plateau Leveling Osteotomy (TPLO)

This procedure uses a fresh approach to the biomechanics of the knee joint and was developed with larger breed dogs in mind. The idea is to change the angle at which the femur bears weight on the flat “plateau” of the tibia. The tibia is cut and rotated in such a way that the natural weight-bearing of the dog actually stabilizes the knee joint. As before the knee joint still must be opened and the damaged meniscus removed. The cruciate ligament remnants may or may not be removed depending on the degree of damage.
This surgery is complex and involves special training in this specific technique. Many radiographs are necessary to calculate the angle of the osteotomy (the cut in the tibia). This procedure typically costs substantially more than extracapsular repair as it is more invasive to the joint.

• Typically, most dogs are touching their toes to the ground by 10 days after surgery although it can take up to 3 weeks.
  
• As with other techniques, 8-12 weeks of exercise restriction are needed.
  
• Full function is generally achieved 3 to 4 months after surgery and the dog may return to normal activity.

Tibial Tuberosity Advancement (TTA)

The TTA similarly uses the biomechanics of the knee to create stability though this procedure changes the angle of the patellar ligament. This is done by cutting and repositioning the tibial crest where the patellar ligament attaches and implanting a titanium or steel “cage,” “fork,” and plate as well as bone grafts to stabilize the new angle. Like the TPLO, bone is cut, and special equipment is needed including metal implant plates. Similar recoveries are seen relative to the TPLO.

Which Procedure is Better?

The TTA and TPLO are much more invasive, much more expensive, and require special equipment and specially trained personnel. They have a greater potential for complications. Are they worth it? For dogs under 45 lbs, it is generally accepted that there is no clear advantage of the newer procedures over extracapsular repair. For larger dogs, there is great controversy. For all the theories behind TPLO and TTA, results in one year post-operative seem to be the same regardless of which of the three procedures the dog had performed. There is some evidence that recovery to normal function may be faster with the newer procedures. Controversy continues and there are strong opinions favoring each of the three procedures. Discuss options with your veterinarian in order to decide.

General Rehabilitation after Surgery

Rehabilitation following the extracapsular repair method can begin as soon as the pet goes home. The area can be chilled with a padded ice pack for 10 minutes a couple of times daily. (Do not try to make up for a skipped treatment by icing the area longer; prolonged cold exposure can cause injury.) Passive range of motion exercise where the knee is gently flexed and extended can also help. It is important not to induce pain when moving the limb. Let the patient guide you. Avoid twisting the leg. After the stitches or staples are out (or after the skin has healed in about 10 to 14 days), water treadmill exercises can be used if a facility is available. This requires strict observation and, if possible, the patient should wear a life jacket. Rehabilitation for patients with the intracapsular repair is similar but slower in progression.

Rehabilitation after TPLO or TTA is gentler. Icing as above and rest are the main modes of therapy. After 3 to 4 weeks, an increase in light activity can be introduced. A water treadmill is helpful. No jumping, running or stair-climbing is allowed at first. Expect the osteotomy site to require a good 6 weeks to heal.

What if the Rupture Isn’t Discovered for Years and Joint Disease is Already Advanced?

A dog with arthritis pain from an old cruciate rupture may still benefit from a TPLO surgery and possibly from the TTA. Ask your veterinarian if it may be worth having a surgery specialist take a look at the knee. Most cases must make do with medical management. Visit our section on arthritis treatment.

Meniscal Injury

We mentioned the menisci as part of the knee joint. The bones of all joints are capped with cartilage so as provide a slippery surface where the bones contact each other (if the bones contact each other without cartilage, they grind each other down). In addition to these cartilage caps, the stifle joint has two blocks of cartilage in between the bones. These blocks are called the menisci and serve to distribute approximately 65% of the compressive load delivered to the knee. The only other joint with a meniscus is the jaw (temporomandibular joint).

When the cruciate ligament ruptures, the medial (on the inner side of the knee) meniscus frequently tears and must either be removed, partly removed, or ideally repaired. This is generally done at the time of cruciate ligament surgery and we would be remiss not to mention it.

Pets with meniscal damage may have an audible clicking sound when they walk or when the knee is examined, but for a definitive diagnosis, the menisci must actually be inspected during surgery. It is difficult to access the menisci and thus repairing a tear in the meniscus is problematic; furthermore, the poor blood supply to the menisci also makes good healing less likely. For these reasons, removal of the damaged portion of the meniscus is the most common surgical choice. This leaves some meniscus behind to distribute the compression load on the knee but removes the painful, ineffective portion.

Areas of current research include techniques to improve blood supply to the healing meniscus so that repair can be more feasible. If meniscal damage has occurred in a cruciate rupture, arthritis is inevitable and surgery should be considered a palliative procedure.

Enhancing Recovery after Surgery

Confinement

Enhancing recovery post-operatively is largely about strict confinement early. This cannot be over-emphasized. Be prepared to crate your dog or employ a pen such as a child’s playpen depending on the dog’s size. A corral of sorts can be constructed with boxes and a baby gate. Be sure you understand the instructions with regard to a gradual return to exercise over several months.

Adequan Injections

A series of Adequan injections can help with joint inflammation as well as lubrication. Typically injections are given twice a week for a total of eight injections.

Glucosamine

Oral joint supplements such as glucosamine contain cartilage building blocks to help the body repair cartilage damage. This is an excellent time to begin supplementation and there are numerous brands.

Weight Management

Overweight dogs have an increased risk for arthritis and cruciate rupture. A weight management program can reduce the potential for arthritis and can reduce the risk of rupture of the opposite cruciate ligament. If your dog is overweight, ask your vet about a weight management plan that might be started during the recovery period.

Professional Rehab/Physical Therapy

Nothing compares to professional rehab for a return to function. If you are lucky enough to have such a facility in your area, consider utilizing their services. A list of home exercises may be obtained and/or the dog can visit weekly or a few times weekly for exercise and treatment. Some facilities allow the dog to board and have daily treatment. Ask your vet about this option.

In Summary

1. In a dog’s knee joint there are two cruciate ligaments that cross, forming an X shape. When either ligament is not intact, the knee is unstable and painful. Usually the ligament at the front ruptures.
   
2. Two types of patients are usually seen. The most common is an adult dog that has had mild lameness that suddenly increases in severity. Sometimes the patients are overweight but not always. It is thought that the ligament has degenerated over time. In these cases, approximately 50% will have the same problem in the opposite knee. Less commonly we see patients who have been involved in some sort of accident that has caused an acute rupture.
   
3. If left alone, it will appear to improve over a week or two but the knee will be notably swollen and arthritis will set in quickly. More importantly, lameness and pain will persist.
   
4. Three different surgical repair techniques are commonly used today: extracapsular repair; tibial plateau leveling osteotomy (TPLO); and tibial tuberosity advancement (TTA).
   
5. The extracapsular repair involves using an artificial ligament replacement. TTA and TPLO are much more invasive and require metal plates and screws. These are more expensive as they require specialized equipment and personnel and can have more complications. For dogs under 45 lbs, there is no clear advantage to the newer procedures. For larger dogs, the choice of which procedure is best is controversial.
   
6. Extracapsular repair: The ruptured ligament is removed and sutures are put through a hole drilled in the tibia; the dog needs 8 to 12 weeks of exercise restriction (outside on a leash only, including the backyard); the suture will break 2 to 12 months after surgery and the dog’s own healed tissue will stabilize the knee.
   
7. TPLO: The tibia is cut and rotated; most dogs are touching their toes to the ground by 10-21 days after surgery; 8-12 weeks of being outside on a leash only including the back yard; full function normally returns within 3 to 4 months.
   
8. TTA: The tibia is cut and repositioned, and titanium, steel, and bone grafts stabilize the new angle of the joint. Most dogs are touching their toes to the ground by 10-21 days after surgery; 8-12 weeks of being outside on a leash only including the backyard; full function normally returns within 3 to 4 months.
   
9. After surgery, patients need strict confinement (this cannot be overemphasized), medications, and weight loss if needed. Water treadmills and other physical therapies are helpful. Rehabilitation is important no matter which method is used.
   
10. Results a year after surgery seem to be the same regardless of which procedure was used. Osteoarthritis will develop in all cases and will cause a degree of lameness.

Toxocara Canis and Toxascaris Leonina: Roundworms of Dogs and Puppies

There are two species of roundworms affecting dogs and puppies: Toxocara canis and Toxascaris leonina. Both are treated with the same medication protocol, so when eggs are seen on a fecal flotation exam, it may not be necessary to determine which species is present. 

While T. canis infects only dogs, T. leonina is also able to infect cats and kittens. Treatment protocols for both worm species are the same. Still, if there are feline household members, it may be useful to specifically identify the roundworm species involved so as to determine which pets are potentially at risk. We will cover each species of roundworm separately, even though treatment is the same for each, their biology is different.

Fresh feces are not infectious. Fresh feces do not contain the infectious stage of T. Canis. Worm eggs require 30 days to become infectious, meaning it is contaminated dirt that is infectious to people and animals.

Toxocara Canis: How Infection Occurs

T. canis is the most common roundworm of the domestic dog, and it is not able to infect cats. Its presence can go completely without symptoms, although more likely it is going to create some degree of diarrhea and possibly vomiting or general unthriftiness in its canine host.

Its life cycle is somewhat complicated, as we are about to see.

1. Consuming infective worm eggs from soil in the environment (generally through normal grooming//self-licking).
2. Nursing from an infected mother dog.
3. Consuming a prey animal (usually a rodent) that is carrying developing worms.
4. During embryonic development when an infected mother dog is pregnant (most puppies are infected this way).

Cats cannot be infected with Toxocara canis but humans can.

Life As A Roundworm

Toxocara Canis has one of the most amazing life cycles in the animal kingdom. It is helpful to understand this life cycle if effective treatment and prevention are to be pursued. It gets complicated so we’ll start with a short synopsis.

It all starts with an infected dog pooping on the ground, with an infected pregnant dog, or with an infected prey animal. In each of these scenarios, an uninfected dog or puppy comes into contact with a roundworm larva that has developed to its infectious stage. The uninfected dog becomes infected by licking contaminated dirt from its feet, from eating an infected prey animal, from developing in its infected mother’s womb, or from nursing its infected mother’s milk. The young roundworm migrates through the new host’s body, ultimately settling in the intestine where it mates and new eggs are produced. The cycle begins again. 

The biggest “take-home” points are these:  

1. Fresh feces on the ground are not infectious, at least with regard to Toxocara, because the worm egg out in the world needs a good month to develop to an infectious stage. 
2. Because the whole body migration drops worms into the intestinal tract over time, one deworming is not enough. Be sure not to skip the second (or even third) treatment. Even better, use a monthly parasite control product that includes a dewormer.
3. Puppies can be assumed to be infected with roundworms when they are born. 
4. Worm eggs can live months to years in contaminated soil.

By that time, the original feces has long since melted away into the ground and is no longer evident. It is the dirt that contains infectious eggs. Toxocara eggs are famous for weathering harsh environmental conditions. Eggs can remain infective for months to years.

Fresh feces are not infectious. Soil contaminated with feces is infectious.

Step Two: A Host Eats an Egg and the Larva Encysts

The egg containing what is called a second-stage larva is picked up from the dirt by a dog or by some other animal, usually in the course of normal self-grooming. The egg hatches in the new host’s intestinal tract and the young worm burrows its way out of the intestinal tract to encyst in the host’s other body tissues. If the new host is a dog, the life cycle proceeds. If the new host is a member of another species, the larvae wait encysted until the new host is eaten by a dog.

Step Three: The Larva Awakens and Migrates Through the Host

These second-stage larvae can remain encysted happily for years. If the host is a puppy under age 6 months of age, the larvae mostly encyst in the host’s liver. In older dogs, the larvae encyst all over the body. When the time comes to move on, the larvae excyst and migrate to the host’s lungs where they develop into third-stage larvae. They burrow into the small airways and travel upward toward the host’s throat. A heavy infection can produce serious pneumonia.  When they get to the upper airways, their presence generates coughing. The worms are coughed up into the host’s throat where they are swallowed thus entering the intestinal tract for the second time in their development.

If the host is pregnant, the larvae do not migrate to the lung after they excyst; instead, they home to the uterus and infect the unborn puppies. The second-stage larvae make their way to the puppies’ lungs to develop into third-stage larvae.

Note: When dogs are dewormed with traditional dewormers, this affects only worms in the intestinal tract. It does not affect encysted larvae. It is difficult to prevent mother-to-puppy transmission, and routine deworming is not adequate. It is possible to prevent infection in unborn puppies by using a specific daily protocol of fenbendazole (your veterinarian can provide details) or selamectin (Revolution®).

Step Four: Finally Back in the Intestine and Ready to Settle Down

Once back in the intestine, the larvae complete their maturation and begin to mate. The first eggs are laid about one week after the larvae have arrived in the intestine and finished molting into their adult stages (about 4 to 5 weeks after the infection has first occurred). From here, the cycle repeats.

Why Is Infection Bad?

Roundworm infection can have numerous negative effects. It is a common cause of diarrhea in young animals and can cause vomiting as well. Sometimes the worms themselves are vomited up which can be alarming as they can be quite large with females reaching lengths of up to seven inches. The worms consume the host’s food and can lead to unthriftiness and a classical “pot-bellied” appearance. Very heavy infections can lead to pneumonia as the worms migrate and if there are enough worms, the intestine can actually become obstructed.

It should also be noted that human infection by this parasite is especially serious (see below). It is important to minimize the contamination of environmental soil with the feces of infected animals so as to reduce the exposure hazard to humans and other animals. In other words, dog feces should be removed and discarded promptly before worm eggs permanently contaminate the local dirt.

How Do We Know If Our Dog Is Infected?

Of course, there are ways to find out if your dog is infected. If a dog or puppy vomits up a worm, there is a good chance this is a roundworm (especially in a puppy). Roundworms are long, white, and described as looking like spaghetti. Tapeworms can also be vomited up, but these are flat and obviously segmented. If you are not sure what type of worm you are seeing, bring it to your veterinarian’s office for identification. You may not know if your dog is infected, and this is one of the arguments in favor of regular deworming. Regular deworming is especially recommended for dogs that hunt and might consume the flesh of hosts carrying worm larvae. Puppies are frequently simply assumed to be infected and automatically dewormed.

Fecal testing for worm eggs is a must for puppies and a good idea for adult dogs having their annual checkup. Obviously, if there are worms present, they must be laying eggs in order to be detected (and there are many reasons why they might not be laying eggs) but, by and large, fecal testing is a reliable method of detection.

How Do We Get Rid Of Roundworms?

Numerous deworming products are effective. Some are over-the-counter, and some are prescription. Many flea control and/or heartworm prevention products provide a monthly deworming that is especially helpful in minimizing environmental contamination.

Common active ingredients include:

1. Febantel (the active ingredient in Drontal and Drontal Plus)
2. Fenbendazole (the active ingredient in Panacur)
3. Milbemycin oxime (the active ingredient in Interceptor, Sentinel, and Trifexis)
4. Moxidectin (the active ingredient in AdvantageMulti, Coraxis, and Simparica Trio).
5. Piperazine (the active ingredient in many over-the-counter products)
6. Pyrantel pamoate (the active ingredient in Strongid, Nemex, Heartgard Plus, and others)
7. Selamectin (the active ingredient in Revolution. Although not included on the US product label, recent studies show effectiveness in the prevention and treatment of canine roundworms.)

The other concept stems from the fact that all the larvae in migration cannot be killed by any of these products. After the worms are cleared from the intestine, they will be replaced by new worms completing their migration. This means that a second and sometimes even a third deworming is needed to keep the intestine clear. The follow-up deworming is generally given several weeks following the first deworming to allow for migrating worms to arrive in the intestine, where they are vulnerable.

Do not forget your follow-up deworming.

Toxascaris Leonina

The life cycle of Toxascaris leonina is not nearly as complicated. T. leonina does not migrate through the body in the way that Toxocara canis does. Instead, the fresh egg is passed by the host in feces, develops into an infectious embryo in the environment, and is swallowed by the new host. The Toxascaris egg develops much faster in the environment than the Toxocara egg and can be infectious for its new host as soon as one week from the time it was passed. Once inside the host, however, Toxascaris development becomes slower. The young worm lives in the host intestine without migrating through the body and becomes a mature worm in 2-3 months. Like Toxocara, Toxascaris can be picked up by wildlife, and the canine or feline host can be infected through hunting and consuming prey. The same dewormers listed above can be used on Toxascaris and must be repeated similarly.

Note: Toxascaris leonina can infect both dogs and cats alike. Unlike the Toxocara situation, unborn puppies cannot be infected by Toxascaris leonina.   

The Same Rules Apply

Basically, the same products listed above will kill Toxascaris leonina. As with Toxocara, removing feces from the environment promptly will greatly minimize contamination and the potential for new infections. Regular use of deworming products is preventive. Toxascaris leonina tends not to produce diarrhea and disease as badly as Toxocara, but we still want to get rid of Toxascaris anyway.

In most cases, the disease is transmitted via a bite wound and it is mostly wildlife that gets infected. When wildlife starts coming into contact with the pet population, then pets become infected and when pets get infected, human infection is not far behind. Because this infection has nearly 100% mortality, preventing it in pets becomes crucial to preventing it in people. Of course, people can get infected by wildlife contact as well. Despite vaccination being readily available, every year the U.S. reports approximately 50 canine deaths, 250 feline deaths, and several human deaths from rabies. Worldwide, some 55,000 human deaths occur annually from rabies even now in the 21st century.

The most common wildlife species to spread rabies to domestic animals and humans in the Northern Hemisphere are skunks, bats, raccoons, foxes, and coyotes. Wildlife (especially bats) are able to gain access to indoor areas where they can come in close contact with both pets and people. Indoor pets are not without risk.

Many people do not realize how fast death occurs from rabies.

The virus in the infected animal’s saliva enters the victim’s tissues during the bite. The virus attaches to the local muscle cells for a couple of days before penetrating local nerves and beginning its slow ascent to the brain. Once within nervous tissue, the virus is not accessible to the immune system and may safely proceed toward the brain. The journey is slow and can take up to a year but the average time is three to eight weeks depending on the species. Virus ultimately reaches the brain and in two to three days more is evident in all body secretions, including saliva. At this point, the disease becomes transmissible and symptoms begin.

It can take up to a year from the time of the initial bite before symptoms begin to show. In dogs, typical incubation periods are 21-80 days. In cats, it’s 28-42 days. Once symptoms show, treatment is nearly impossible.

Prodromal Stage (The First 2-3 Days After Symptoms Have Started)

A change in personality is noted. Friendly animals become shy, etc. The larynx begins to spasm and a voice change may be noted (especially true in rabid cattle). Most infected animals will actively lick or scratch the site of the original bite.

Excitative Stage (Next 1-7 Days)

Classically, this would be the “mad dog” stage, though, in reality, most animals skip this phase altogether. The animal has no fear and suffers from hallucinations. If confined, the animal often attacks the bars of the cage.

Paralytic or Dumb Stage (Next 2-4 Days)

Weakness/paralysis sets in. The larynx is paralyzed, resulting in an inability to swallow, thus drooling and “foaming at the mouth” result. The animal dies when the intercostal muscles that control breathing are paralyzed. It is from animals in this stage where most human exposure occurs. There is no treatment for animals or humans once clinical signs appear.

When human exposure to the animal in question is involved, what happens depends on an assortment of criteria. If the animal in question is dead, its brain can be tested for rabies. There is no test for rabies in a living animal but since we know that death follows quickly after the virus becomes contagious, a living animal can be confined for 10 days. If the animal is still alive 10 days after biting a person, then the bite could not have transmitted rabies.

Prevention

For Our Pets

Happily, rabies prevention is accomplished with vaccination and limiting exposure to wildlife. The standard killed virus vaccines are available for both dogs and cats and, after the initial dose which is good for one year, subsequent doses are generally good for three years. Because tumors have developed in cats who received the killed virus vaccine, a recombinant product is now available that uses a portion of rabies viral DNA cloned into a harmless canarypox virus. This arrangement allows the pet to realize the benefits of live virus vaccination without any risk of exposure to the living rabies virus.

Rabies vaccination protocols are typically controlled by municipal regulations. Most communities legally require the vaccination of all dogs. The American Association of Feline Practitioners recommends rabies vaccination as a core vaccine for all pet cats.

For pets not current on rabies vaccination that have been exposed to biting wildlife, the Texas Post-Exposure Rabies Prophylaxis Protocol has been particularly helpful. In this situation, the pet should be vaccinated for rabies as soon as possible after the wildlife bite with booster vaccines given three weeks post-bite and eight weeks post-bite. The pet should be strictly isolated for 90 days. This protocol has been extremely successful in preventing rabies symptoms and contagion when normal rabies vaccination had lapsed. 

Treatment for Humans (Post Exposure Prophylaxis or PEP)

Every year a small number of people die of rabies in the U.S. Most of these people were bitten by a dog, bat, or some other animal and did nothing other than basic first aid. Recall that it takes many weeks for the rabies virus to reach the brain. This allows time for the vaccine to be given so that when the virus “comes out” of its neurologic hiding place and is ready to infect the brain, a substantial immunologic response is waiting. The virus is foiled and clinical rabies does not result.

If you are bitten by an animal and its rabies vaccination history is unknown, there are definite steps to take. A fresh bite wound should be washed out with water quickly as this may wash out viral particles. The time it takes for the virus to reach the brain depends on the amount of virus in addition to how close the wound is to the head. This simple step can be life-saving.

If the biting animal is alive, its vaccination status should be confirmed as soon as possible and it will need to be confined according to local law. The bite wound should be reported to the health department as soon as possible. Only rodent and rabbit bites are not reportable.

If the animal is dead then its brain can be tested for rabies. The head of the biting animal is submitted to the health department for fluorescent antibody testing for the rabies virus. This process takes a matter of hours so that any bite victims can know right away if they will require rabies treatment.

If the animal is not available or its vaccination status is in question, further treatment may be needed. Hyperimmune (antibody-rich) serum is flushed into the wound in hope of inactivating the virus before it may penetrate to the nerves. The patient receives a vaccination on a regular schedule for about a month, as described above.

Veterinarians have a rabies exposure risk of more than 300 times that of the general population. 

Anyone pursuing a career with animals should consider vaccination against rabies.

The purpose of the quarantine period is to determine if the rabies virus could have been in the animal’s saliva at the time of the bite. An animal infected with rabies and shedding virus will certainly be dead within ten days.

If the biting animal is known to have been exposed to wildlife, the situation is different. A vaccinated animal must be re-vaccinated within the time period required by local regulations and confined for observation for the specified duration. Unvaccinated animals may be confined for a specified time period according to local/regional law, or be euthanized and tested for rabies. In the U.S., all bites to humans that break the skin are reportable to local health departments. Rabies vaccination requirements vary from state to state, and country to country.  Contact your veterinarian if you think your pet has come into contact with or been bitten by a wild animal. Regardless of the vaccination status of your pet, wild animal bites may lead to painful wounds and infection.

Again, laws regarding biting dogs and rabies vaccination are highly regional. Check with your local animal regulation department, your veterinarian, or visit rabiesaware.org to find out what you need to know in the U.S..

Quarantines when Traveling

Great Britain, Hawaii, Japan, New Zealand, and several other island areas have successfully eradicated rabies from their territory. These places are EXTREMELY cautious about allowing in potential carriers of rabies. Because of the long incubation period of rabies, a very long quarantine is needed; however, this must be balanced by the expense associated with quarantine and owners’ reluctance to be separated from their pets. Most places that have eradicated rabies have protocols for avoiding or minimizing quarantine. Typically, a microchip is implanted in the pet for identification purposes, a rabies antibody titer (a measurement of vaccine-induced protection) must be performed at an approved laboratory, and rabies vaccine documentation is necessary.

For listings of what each state requires for entry, go to the USDA. 

For travel to another country check with that country’s consulate, but guidelines are also available at USDA.

Other Links

The CDC’s rabies home page has, in addition to basic information, a children’s education area that is particularly helpful for families who go camping.

The annual World Rabies Day calls attention to this problem to raise awareness and provides information about rabies in both humans and animals.

In Summary:

You can’t treat rabies once symptoms set in; all you can do is prevent it.

Rabies is a virus transmitted through saliva or brain tissue. Without rapid preventive treatment, it is almost always fatal. That’s why your pets are required to have rabies vaccines in many areas of the world.

The most common wildlife species to spread rabies to animals and people in the Northern Hemisphere are bats, skunks, raccoons, foxes, and coyotes. 

It is generally caused by a bite wound, and mostly wildlife gets infected.

Rabies affects a mammal’s central nervous system. It can take up to a year before symptoms begin to show, but the average time is 3-8 weeks depending on the species. In dogs, the typical incubation period is 21-80 days. In cats, it’s 28-42 days. Once symptoms begin, treatment is nearly impossible.

If you are bitten, you need a preventive injection immediately as it only works during the incubation period. Once even mild symptoms begin, death occurs within 10 days.

After symptoms have started:

•  First 2-3 days: a personality change is seen, and the larynx spasms, resulting in a voice change.
•  Next 1-7 days: this is the “mad dog” stage in which an animal has no fear and suffers from hallucinations, but many skip this stage.
•  Next 2-4 days: weakness and paralysis set in. The larynx becomes paralyzed so the animal cannot swallow, causing drooling and foaming at the mouth.
•  The animal dies when the muscles that control breathing finally become completely paralyzed. Most people get bitten in this stage.

Symptoms may not be obviously recognizable, making diagnosis difficult if not impossible. There is no diagnostic test for rabies in a living animal.

What happens after people are exposed depends on the situation. If the animal is dead, its head is sent to a laboratory so the brain tissue can be tested. In some circumstances/locations, a living animal can be quarantined for 10 days at the owner’s expense; if the animal is still alive, then the bite could not have transmitted rabies.

The vaccine protocols are typically controlled by municipal regulations. Most communities legally require all dogs to be vaccinated and recommend it for cats. Vaccination requirements vary from state to state, and country to country. 

Exposed pets not current on rabies vaccination should be given booster vaccines at 3 and 8 weeks post-bite. The pet should be strictly isolated for 90 days.

Exposed humans should wash the bite with water as it may wash out some virus particles; the time it takes for the virus to reach the brain depends on the amount of virus in addition to how close the wound is to the head.  This step could save a life.

Animal bites need to be reported to local health departments.

Veterinarians have a rabies exposure risk of more than 300 times that of the general population. Anyone in an animal-oriented job should consider preventive vaccination.

What Kind of Infection is it?

The characteristic ring appearance is primarily a human phenomenon. In animals, ringworm frequently looks like a dry, grey, scaly patch but can also mimic any other skin lesion and have any appearance. 

Where Would My Pet Pick Up This Infection?

The spores of dermatophyte fungi are extremely hardy in the environment; they can live for years. All it takes is skin contact with a spore to cause infection; however, the skin must be abraded, as the fungus cannot infect healthy, intact skin. This means that freshly shaved, scraped, or scratched skin is especially vulnerable.

Infection can come from direct contact with an infected symptomatic animal, direct contact with an asymptomatic carrier, or contact with spores in the environment. Infected symptomatic animals have skin lesions rife with fungal spores. Carriers may be infected animals who do not have obvious lesions (a common scenario towards the end of treatment), or they may be animals who are not actually infected per se but simply have spores on their hairs, just as a couch might have spores on its surface. Infection is transmitted when spores bind to abraded skin. Skin lesions typically appear one to three weeks after exposure.

There are several species of dermatophyte fungi. Different species come from different kinds of animals or even from the soil, thus, determining the ringworm species can help determine the source of the fungal infection. Predisposing factors towards infection include age (puppies and kittens are at higher risk than adult animals), lifestyle (free-roaming or hunting animals being predisposed), and local climate (pets living in warmer, more humid climates are predisposed). Immune suppression from the FIV or Feline Leukemia Virus turns out not to be a predisposing factor as one might expect, especially since immune suppression is a human risk. Still, there are two breed predispositions of note: Persian cats and Yorkshire terrier dogs. Infection rates are higher in these breeds, as are treatment failures.

Can I get This Infection?

How Does the Doctor Know This is Really Ringworm?

In some cases, we know for sure that the pet has dermatophyte fungi, while in other cases, we are only highly suspicious. Ringworm lesions on animal skin are rarely the classic ring-shaped as in people (in fact, in animals, lesions are often not even itchy) thus, some testing is usually necessary, as we will describe.

Wood’s Light (Fluorescence)
A Wood’s light is a lamp designed to emit light in a specific range of wavelengths. It looks like a black light but is actually entirely different. Ringworm fungi of the genus Microsporum (the most common genus in small animal ringworm cases) demonstrate a chemical reaction when they bind to hair shafts. This chemical reaction fluoresces apple green under the Wood’s light. Fungal spores will not fluoresce without infection, so an uninfected carrier will not fluoresce, nor will debris that is not attached to the hair.

There is controversy regarding what percentage of Microsporum infections will fluoresce. A commonly published statistic is that approximately 50 percent will fluoresce, but other information suggests that 100 percent of Microsporum infections will fluoresce at least at some point in their course. Fluorescence first becomes detectable five to 18 days post-infection. In many cases, using Wood’s light uncovers numerous additional skin lesions that were not visible to the naked eye.

Most veterinary hospitals are equipped with Wood’s lights and use them to screen pets for ringworm lesions. Unfortunately, fluorescence may be difficult to find, and complicating matters, many topical products and non-infectious debris will also fluoresce. Further testing is often needed.

Microscopic Examination

Fungal culture does not depend on a visible skin lesion. A pet with no apparent lesions can be combed over its whole body and the fur and skin that are removed can be cultured. Carrier animals are usually cats living with several other cats.

A specific growth-medium, called dermatophyte test medium, is commonly employed to distinguish ringworm fungi from other fungi. Ringworm fungi classically produce a white fluffy colony and will turn the orange growth medium red within two to 14 days. When the colony is mature, the material can be harvested from it and examined under the microscope for ringworm spores.

PCR Testing

The newest diagnostic method involves testing hairs for dermatophyte fungus DNA. The benefit is that it is much faster than the culture but is still able to confirm the infection as well as determine the species of ringworm fungus involved. This makes PCR testing an excellent way to make the diagnosis of ringworm initially but can pose a problem in determining the end of treatment. The downside of PCR testing is that it tests for fungal DNA, not for live viable fungi. When the pet is first diagnosed, if there is fungal DNA  on a skin lesion, we can assume the fungus is causing infection. After treatment, however, the fungus is killed or damaged to the point of being harmless, but its DNA will still be there, creating a positive PCR test. For this reason, PCR is best used for detecting fungus in an untreated patient, but culture is probably best at determining when treatment can be discontinued.

Biopsy

Sometimes the lesions on the skin are so uncharacteristic that a skin biopsy is necessary to obtain a diagnosis. Fungal spores are quite clear in these samples, and the diagnosis may be ruled in or out. Depending on the outcome of preliminary tests, your veterinarian may begin ringworm treatment right away or postpone it until after more definitive results are available.

Treatment

Commitment is the key to success, especially if you have more than one pet. Infected animals are constantly shedding spores into the environment (your house) thus disinfection is just as important as treatment of the affected pet. The infected pet will require isolation while the environment is disinfected and should not be allowed back into the clean area until a culture is negative. Ideally, all pets should be tested and isolated until they are deemed clear of infection, at which point they can be allowed back into the clean area.

Infected pets generally require oral medication, which may be supplemented with topical treatment (dipping, lotion, or both). Localized lesions might get away with topical treatment only.

Oral Medication for Infected Pets

Oral medication provides the foundation for treating ringworm as it is an oral medication that renders the fungus unable to reproduce and spread. With the spread of infection controlled, only the pre-existing fungus remains and generally can be removed with topical therapy as described later on.

Currently, two medications are primarily recommended to treat ringworm:  Itraconazole and terbinafine.  (Griseofulvin is also available and has been the traditional anti-ringworm oral medication for decades. While griseofulvin is still as effective as the other medications, the newer products appear to be safer, and griseofulvin is rapidly becoming only a historical note.)

Treatment with oral medication typically should not be discontinued until the pet’s cultures are negative. Stopping when the pet simply looks well visually frequently invites the recurrence of the disease.

Itraconazole

This medication is highly effective for ringworm. Recently, it has become available in an oral suspension (liquid) approved for cats, which is most likely going to be the form your veterinarian prescribes. Itraconazole is also available as a human product, in either capsules or liquid. The human product is not practical for pet use as the capsules are too strong and the liquid too weak. If the human product is to be used, it is important to obtain it through a compounding pharmacy into appropriately sized capsules using the brand name Sporonox®, rather than from generic. The reason for this is bioavailability (how much of the consumed drug actually makes it into the body after swallowing it). Generics and bulk products simply have poor bioavailability and are not recommended.

Compounded itraconazole is expensive and compounded itraconazole from a brand name product is even more expensive, but investing in a medicine that is not bioavailable is even worse so it is important to get either brand name Itrafungol® made for cats or brand name Sporonox® made for humans (and reformatted into a pet-sized dose). On average, cats treated with itraconazole and nothing else were able to achieve a cure two weeks sooner than cats treated with griseofulvin. 

After deciding which form of medication to use, there are several dosing regimens that have been used: daily, one week on/one week off, two weeks on/two weeks off, and the list goes on. The bottom line is that itraconazole is effective against ringworm in any of the protocols. As with any drug, side effects are possible, including nausea. 

Terbinafine
This is a newer antifungal on the scene and seems to be effective against ringworm fungi. While originally expensive, the generic form is currently relatively inexpensive. Terbinafine is best given with food and cannot be used during pregnancy or nursing.

Griseofulvin
This medication must be given with a fatty meal in order for an effective dose to be absorbed by the pet. Persian cats and young kittens are felt to be sensitive to its side effects, which usually are limited to nausea but can include liver disease and serious white blood cell changes. Cats infected with the feline immunodeficiency virus commonly develop life-threatening blood cell changes and should never be exposed to this medication. Despite the side effects, which can be severe for some individuals, griseofulvin is still the traditional medication for the treatment of ringworm and is usually somewhat less expensive than itraconazole. Treatment typically takes one to two months.

Lufenuron – Not Effective against Ringworm

Lufenuron is an oral product used in flea control. It works by inhibiting the insect’s ability to make chitin, an important component of its exoskeleton. It turns out that dermatophyte fungi also have chitin in their cell walls and some initial research suggested that lufenuron was a helpful adjunct to other more conventional treatments. This has not panned out in the long term and its use has been largely abandoned. Lufenuron is the flea-sterilizing ingredient in both Program and Sentinel.

Topical Treatment for Infected Pets

While the oral products suppress the infection on the host, they do not kill the spores. Topical treatment acts by directly killing fungal spores.  This is not only valuable in preventing environmental contamination by the infected animal but also is important in preventing infection in animals who come into contact with the infected animals. Topically treated hairs will not be infectious when they drop into the environment. In situations where it is difficult to confine the infected animals away from the non-infected ones, topical therapy becomes especially important. So what sort of options are available?

Lime Sulfur Dip

Dips are recommended twice a week and can be performed either at the hospital or at home. If you attempt this kind of dipping at home, you should expect:

1. Lime sulfur will stain clothing and jewelry
2. Lime sulfur will cause temporary yellowing of white fur
3. Lime sulfur smells strongly of rotten eggs.

The dip is mixed according to the label instructions and is not rinsed off at the end of the bath. The pet should be towel dried. Shampooing is not necessary.

Miconazole-Chlorhexidine Rinse or Shampoo

Miconazole (an antifungal) and chlorhexidine (a disinfectant) synergize with each other when combatting ringworm. They are available as a combination rinse as well as shampoo.  The rinse, which is left to dry on the pet, is effective in killing ringworm spores though in the field lime sulfur seemed associated with a faster cure (median 48 days vs. 30 days with lime sulfur).  Allow a 10-minute contact time for a miconazole-chlorhexidine shampoo. Twice weekly application of either rinse or shampoo is the currently recommended frequency of use.

There are also products where chlorhexidine and miconazole are used as single agents. Chlorhexidine alone is not effective and miconazole alone is effective but is vastly more effective when synergized with chlorhexidine. It is best not to use these products separately.

Topical Lotions and Ointments

There are numerous antifungal products available to treat isolated lesions. Miconazole, clotrimazole, and other anti-fungal topicals can be applied in this way but these treatments should be considered adjuncts to other therapies.

Environmental Treatment

The problem with decontaminating the environment is that few products are effective. Bleach diluted 1:10 will kill 80 percent of fungal spores with one application and any surface that can be bleached, should be bleached. It should be noted, however, that bleach cannot disinfect anything if there is any dirt or grime. General cleaning should always precede disinfection. Vigorous vacuuming and steam cleaning of carpets will help remove spores and, of course, vacuum bags should be discarded. Wood floors can be decontaminated with the daily use of an electrostatic cloth, such as Swiffer, and twice weekly wood soap cleaning. Laundry can be decontaminated by running it through a washing machine twice; bleach is optional. The rest of the house can be disinfected during this confinement period. Be sure to clean areas with a detergent or soap to remove organic debris as disinfection will not work if the surface is not clean first. Cultures of the pet are done monthly during the course of treatment.

To reduce environmental contamination, infected cats should be confined to one room until they have cultured negative.

The following specific recommendations for environmental disinfection come from the Dermatology Department at the University of Wisconsin School of Veterinary Medicine. This cleaning protocol should be used in the room where the affected individuals are being housed:

• The hairs and skin particles from the infected individual literally form the dust and dirt around the house and are the basis for reinfection. The single most important aspect of environmental disinfection is vacuuming. Target areas should receive good suction for at least 10 minutes and hard surfaces should be cleaned with a Swiffer or similar product. (Many people like to use an inexpensive vacuum that can simply be thrown out when the ringworm episode is over.)
  
• Affected animals should be confined to one room which should be cleaned twice a week.
  
• Areas that have been contaminated should be cleaned with soap and water and rinsed with water. This process is performed at least three times weekly. For carpeting, a steam cleaner can be used. The steam is not hot enough to kill ringworm spores but should help clean the dirt and remove the contaminated particles.
  
• After the triple cleaning with soap and water, a 1:10 solution of bleach should be used on surfaces that are bleachable. The surface should stay wet for a total of 10 minutes to kill the ringworm spores. Bleach will not kill spores in the presence of dirt so it is important that the surface be properly cleaned before it is bleached.
  
• Wood floors can be decontaminated by daily use of disposable cleaning cloths such as a dry electrostatic cloth. The floors are then cleaned twice weekly with wood soap.

To determine if an area has been properly decontaminated, use the following process: Use a piece of electrostatic cloth on the area to be tested, and dust for 5 minutes or until the cloth is dirty. 

Once a cat cultures negative and is removed from the contaminated room, decontamination should be achieved in one to three cleanings.

The ringworm fungus can remain infective in the environment for up to 18 months, maybe longer.

Identifying Carriers

When there is a pet with ringworm in the home, all other pets should be tested. A carrier of ringworm is one that is infected but not showing lesions. Usually, this will be the pet that has been treated for a while and appears visually to be cured but, in fact, is still infected or one that is simply carrying the fungus on its fur in the same way an inanimate object might have fungal spores on its surface. Both types of carriers must be identified as they are both capable of spreading the infection.

The MacKenzie Toothbrush Test is the best approach for the pet with no obvious lesions. Here the pet is combed with a clean toothbrush, and the hair that comes off is cultured for ringworm. This allows sampling of the whole cat when no lesions are visible either with the naked eye or with the Wood’s lamp.

Will Ringworm Go Away by Itself?

There have been several studies that showed this fungal infection should eventually resolve on its own. Typically, this takes 4 months, a long time in a home environment, for contamination to be occurring continuously. Actively treating the infection is considered a better approach than simply waiting for it to go away while environmental contamination progresses.

What to Change if the Outbreak Seems to Go on Forever (as in more than 100 Days)

After a couple of months of medication and dipping, the outbreak is generally over.

If the outbreak is still going strong, then it is time to look for corners that may have been cut and holes in the program that need patching:

1. If you are using visual lesions as the endpoint for treatment, it is important to change to fungal culture as the standard.
   
2. Dipping is labor intensive, and people tend not to do it twice a week as is optimal. Twice a week dipping should be instituted if there is trouble eradicating the infection.
   
3. The environment must be properly decontaminated, and this includes not just identification but confinement of affected pets. If infected pets are not confined, they will contaminate the environment and keep getting re-infected.
   
4. Consider whether the pet has a defective immune system. If the pet has a second disease, it must be controlled if the pet is to recover.
   
5. Itraconazole compounded from bulk products does not have the same bioavailability as itraconazole compounded from prescription products. This means, in short, that it does not work as well. Changing to compounded prescription products or to terbinafine may make a big difference.
   
6. Lastly, it is important to consider that the diagnosis may be wrong if only visualization were used to make the diagnosis. Proper testing as outlined above is crucial to the diagnosis of dermatophytosis. A biopsy may be needed.

If you become infected, contact your doctor to receive treatment. Veterinarians are not able to make recommendations for human disease or infection, even if the infection came from a pet.

In the United States, RMSF is most common in the southern Atlantic states, western central states, and areas of the mid-Atlantic and southern New England coastal states. According to the Centers for Disease Control and Prevention (CDC), only about 1 to 3 percent of the tick population carries R. rickettsii, even in those geographic areas.

Prior research indicated that the infected tick must be attached for at least 2 hours in order to transmit disease. Research in Brazil demonstrated that unfed ticks had to be attached for more than 10 hours for transmission to occur, whereas fed ticks could transmit disease within as little as 10 minutes after attachment. These results may indicate that transmission across all tick species could occur earlier than once thought, depending on when the tick has last eaten. Transmission of the Rickettsia can then occur due to the bite or from exposure to the parasite while handling the tick. 

Clinical Signs

Clinical signs will show up 2 to 14 days after the bite occurred. The parasite creates an inflammation of the body’s small blood vessels, which results in damage to all the organs of the body.

Common signs include fever, lethargy, inappetence, pain, eye/nose discharge, nosebleed, cough, enlarged lymph nodes, lameness, skin necrosis/sloughing, hemorrhage, and peripheral swelling. Petechial hemorrhages (tiny hemorrhages in the skin) will occur in about 20% of affected dogs. Up to one third of the infected dogs will have central nervous system signs (lack of voluntary coordination of muscle movements, weakness, balance problems, cranial nerve abnormalities, seizures, stupor, spinal pain, etc.). Any organ in the body may be affected and the clinical signs may be mild or severe enough to result in death.

Diagnosis

Diagnostic tests for RMSF include blood tests looking for severely low platelet count, plus coagulation profiles, blood chemical analysis, and serology. (Paired titers, from blood samples taken 14 to 21 days apart, are often needed, but a single high titer in dogs that have clinical signs is consistent with an active infection.)  Response to antibiotic therapy is suggestive, but not diagnostic.

Treatment/Management

Specific treatment relies on the use of appropriate antibiotics. Response to the antibiotics usually is seen within 24 to 48 hours, although advanced cases may not respond at all to treatment. The most common antibiotics used are tetracycline, doxycycline, and minocycline. Chloramphenicol is usually reserved for pregnant bitches or young puppies. Fluoroquinolones, such as enrofloxacin, have shown efficacy, but their use is generally restricted to older animals. Side effects to any of the antibiotics may be seen. Your veterinarian will choose the antibiotic that best suits your pet’s age, pregnancy status, etc.

Blood transfusions to treat anemia and other supportive therapies may be needed.

Prognosis

Prognosis is excellent in dogs that are diagnosed and treated early and who have no complications. Lifelong immunity often occurs after the infection is cleared.

More severely affected patients are at higher risk for complications, such as kidney disease, neurological disease, vasculitis, and coagulopathies. Prognosis is guarded for patients that have complications.

Prevention

Limit your dog’s exposure to ticks and tick-infested areas.

Inspect your dog closely for ticks. The sooner you can remove a tick after it attaches, the better the chance that the organism will not have had time to become infective. Wear gloves when removing ticks, as the infective organism can get into your body through abrasions, cuts, etc. You can also use a tick remover tool. 

A recessed (or juvenile) vulva means a dog has excess skin folds that hang over her vulva, enough to potentially cause problems of one kind or another. The skin folds are a structural problem thought to possibly be a genetic issue, but the genetic connection has not been determined. The condition tends to be seen mostly in medium to large-sized breeds, most often in obese dogs.

Some dogs will never have one single problem related to having a recessed vulva, and it will be found during a physical exam or during a procedure for something unrelated. However, some dogs will have life-long problems because the vulvar area collects some moisture when the dog urinates. Combined with body heat in that area, the moisture creates a perfect breeding ground for bacteria and predisposes the dog to urinary tract infections or vaginitis. The vagina is normally not sterile. The bacteria can infect the skin folds, which is called perivulvar dermatitis, move into the vagina causing vaginitis, or move up into the urinary tract, which leads to a bladder infection.

Your veterinarian can diagnose a recessed, or hooded, vulva simply by looking at the genital area, and the vulva is not seen because it’s covered with skin folds.

Clinical signs tend to depend on how much inflammation and infection the dog has. Your dog may scoot on her behind, trying to relieve the itching in her vulva (it may look like a dog scooting because of inflamed anal glands), or licking her vulva excessively.

You may notice a bad odor from her vulva; that odor is usually from infected tissues. Some dogs might leak urine while sleeping or resting due to a condition called USMI, which is a common problem in spayed dogs and could also potentially contribute to a bladder infection (bacterial cystitis).

If she has a bladder infection, you may see blood in her urine, accidents in the house even if she is perfectly housetrained, see her straining to urinate, or notice a foul odor from her urine. It’s possible that her signs of a bladder infection are the only ones you will see if she has a recessed vulva.

Overall, bacterial cystitis is a common medical problem for female spayed dogs (in general) in that many of them may have a bout of bacterial cystitis during their lifetime. Repeated or recurrent bouts of bacterial cystitis are more problematic and it’s important to look for underlying drivers. A recessed vulva could be one of these predisposing causes.

Treatment

If the skin folds of the recessed vulva are affecting both your and your dog’s quality of life, your veterinarian can provide medical management or a surgical fix. Medicated shampoos or wipes may be enough to prevent skin infections. In overweight dogs, weight loss will likely help because there would be less tissue to fold over the vulva. If your dog has not gone through a heat cycle, the recessed vulva might improve after the first heat cycle.

The surgical procedure is called a vulvoplasty. Prior to surgical intervention, it’s important to investigate and look for co-morbid causes for recurrent bacterial cystitis. The evaluation typically includes a physical examination, complete urinalysis, urine culture, possibly a complete blood count, and a chemistry panel. Imaging with radiographs (X-rays) and a complete abdominal ultrasound are also likely to be done. Direct visualization of the lower urinary tract and vagina can be performed with cystoscopy, and this is often done prior to vulvoplasty surgery in order to look for problems such as malformations and other abnormalities.

During vulvoplasty, the surgeon removes a piece of tissue from around the vulva so that the skin has a more normal structure. The new ventilation helps the skin dry out and not be moist enough all the time for bacteria to grow. Additionally, it keeps those skin folds from rubbing up against each other and causing irritation.

You may be provided with analgesics for pain and possibly antibiotics to prevent an infection. Some dogs will need sutures; most types will need to be removed in about 10-14 days at the follow-up appointment.

Before the vulvoplasty occurs, any skin infection near the vulva must be cleared up as it prevents the incision from healing normally, usually by taking antibiotics. A skin culture can determine the most appropriate antibiotic.

Appropriate post-operative care is critical: for two weeks she must be kept quiet with restricted activity, as otherwise during running, jumping, and playing the incision can rip open. That can cause some serious complications. She should be taken outside only on a leash. An e-collar needs to stay on so she will not lick the incision, which also can cause infections.

Rarely, in dogs with significant skin folds, it is possible that not enough skin is removed during the procedure. In this case, the symptoms will likely return. A second surgery can correct it.

Generally, however, the prognosis after a vulvoplasty is excellent and most owners are quite pleased.

On the last program of Texas Vet News I talked about the large number of oral joint health supplements that are on the market for horses.  Even though these products are widely used, many of them are of questionable quality because there are no regulations governing them.  Because of this problem, Dr. Stacey Oke has developed a system for horse owners to help them choose a product that may be of better quality than some others. 

First of all, choose a product from a company that has been in the animal health pharmaceutical business for years instead of months.  It is likely that companies with a good reputation are not going to stake their reputation on manufacturing a poor quality product for short-term sales.  Also, look for products that are backed by clinical research published in peer-reviewed veterinary journals.  Many companies report they have clinical trials but don’t have information available; even if they do have information, clinical trials that are not published in peer-reviewed journals are worthless. 

It is also important to look at the label and make sure all of the ingredients in the product are listed, including active, inactive, and filler ingredients.  Manufacturers that do not list all ingredients of their products likely use fillers and may not contain the labelled ingredients.  Products that make claims that seem too good to be true are probably not as good as they claim. 

Dosing instructions should be accurate and clear, and the amount of ingredient per scoop should be printed clearly on the label.  Also, look for products with clear contact information and check to see if the company you choose has veterinarians on staff to answer your questions. 

Did you know that skin diseases account for as much as 25% of the cases seen by small animal veterinarians?

Skin problems typically faced by pets and their owners include:

1.   Itching
2.   Dandruff
3.   Blackheads
4.   Odor
5.   Crusting
6.   Redness
7.   Rashes
8.   Oiliness

The nutritional aspect of skin disease is quite broad. There are true nutritional deficiencies that affect the skin and other skin diseases that can be made dramatically better by using supplements.

Just because a condition responds to a nutrient does not necessarily mean that there is a deficiency of it.

Everyone wants their pet to have a lustrous beautiful coat and would like to do what it nutritionally possible to ensure this. Recently essential fatty acids have received a great deal of press. A brief primer follows. 

What is a Fatty Acid?

Biochemically, a fatty acid is what we just call fat. When we talk about different types of fatty acids, we are talking about different types of fat. A fatty acid consists of a long carbon chain (say 20 or so carbons in length) with biochemical acids called a carboxyl group at one end and a methyl group on the other end.

Saturated Vs. Unsaturated

Each carbon has four binding sites. In the carbon chain, two sites will be taken up by other carbons (i.e., the two adjacent carbons on the chain). In a saturated fat, the other two sites are taken up by hydrogen atoms. Saturated fats are typically solid at room temperature, like lard and butter, and are usually made from animals. Saturated fats are generally burned as fuel by our bodies. An example of a saturated fatty acid is depicted in the above illustration.

Unsaturated fats have two adjacent carbons held together by a biochemical double bond. These fats are generally liquid at room temperature and come from plants, such as olive oil, corn oil, etc.

Unsaturated fats can be classified as omega three fatty acids or omega six fatty acids, depending on the location of the double bond relative to the methyl group at the end of the chain. These types of fatty acids are essential, meaning that our bodies cannot make them; instead, we must eat them in our diet. These fats are not burned for fuel but are used as structural components.

The omega six fatty acids are used as the main structural components in our cells. Omega three acids are used in the retina and central nervous system.

For healthy skin and coat, the diet must contain adequate omega six fatty acids as these make up the surface of the skin.

Examples of omega six fatty acids (also called n-6 fatty acids): Linoleic acid, gamma linolenic acid, and Arachidonic acid. Evening Primrose oil is an excellent example.

Examples of omega three fatty acids, also called n-3 fatty acids, include: Alpha linolenic acid (ALA), Eicosatetraenoic acid (EPA), docosahexaenoic acid (DHA).

Cold water fish oils are an excellent source of DHA and EPA. A terrific source of ALA would be flax seed oil. DHA has anti-inflammatory properties, which is why it is so frequently recommended in inflammatory conditions. Many people prefer to use flax seed oil as their omega 3 source because flax seed oil does not taste fishy and people readily convert ALA to DHA. This is great for people but it turns out that pets are only able to convert about 10% of ALA to DHA, so for them cold water fish oils are better. Fortunately, most dogs and cats like the fishy taste. 

Should we Supplement Essential Fatty Acids?

There is no question that a diet must contain adequate omega 6 fatty acids to maintain optimal skin and coat quality. A diet found to be “complete and balanced” will have an amount of omega 6 fatty acids that should be optimal for a normal animal.  

But there’s more.

Omega 6 Fatty Acids and Dandruff

Research has shown that dogs with oily, dandruffy skin (seborrhea) have insufficient omega 6 fatty acids in their skin despite eating a diet that should be optimal. When omega 6 fatty acids are supplemented, the seborrhea improves. This finding supports the old-time remedy of adding a spoonful of corn oil to the diet to ensure a glossy coat. Seborrhea is a complex condition but animals with it may need more omega 6 fatty acids.

Anti-Inflammatory Effects of Omega 3 Fatty Acids

Omega 6 fatty acids constitute our cell membranes. During some biochemical situations, it is necessary to produce hormone-like substances called prostaglandins and leukotrienes. These substances are made from omega 6 fatty acids and the resulting prostaglandins and leukotrienes are not necessarily good for us. In fact, these substances are responsible for itching and inflammation leading to the clinical skin problems listed above. One way to address this is to supplement omega 3 fatty acids, which become incorporated into cell membranes along with the omega 6s. After a couple of months of supplementation, omega 3 fatty acids infiltrate cell membranes significantly. When it comes time to make prostaglandins, the omega 3s are mobilized instead of the omega 6s only in this case, the prostaglandins that result are not inflammatory. When omega 3 fatty acids are supplemented, itching can be substantially reduced and even arthritis pain improved.

One problem with this is that no one really knows how much omega 3 fatty acid to supplement. There is some evidence that a ratio of omega 6 to omega 3 fatty acids in the supplement is crucial. If this is so, clinical research becomes hugely complicated as the diets of pets cannot be standardized easily for study. If pets in a study eat different diets, then it is impossible to tell what overall omega 6:omega 3 ratio each is receiving. Essential fatty acids are being pursued as treatment for diseases of virtually every organ system; watch for new research in this area.

Conditions that Have Been Shown to Benefit from Omega 3 Fatty Acid Supplementation

1.   Renal (kidney) insufficiency
2.   Heart failure
3.   Lymphoma
4.   Airborne allergies

Research is ongoing. We know that supplementing with omega 3 appears to be benign with the potential to do a great deal of good. 

• It develops deep within the bone and becomes progressively more painful as it grows outward and the bone is destroyed from the inside out. The lameness goes from intermittent to constant over 1 to 3 months. Obvious swelling becomes evident as the tumor grows and normal bone is replaced by tumorous bone.
  
• Tumorous bone is not as strong as normal bone and can break with minor injury. This type of broken bone is called a pathologic fracture and may be the finding that confirms the diagnosis of bone tumor. Pathologic fractures will not heal and there is no point in putting on casts or attempting surgical stabilization.

How do we Know my Dog Really has an Osteosarcoma?

Radiographs (x-rays)

The lytic lesion looks like an area of bone has been eaten away. One of the first steps in evaluating a persistent lameness is radiography (x-rays). Bone tumors are tender so it is usually clear what part of the limb should be radiographed. The osteosarcoma creates some characteristic findings.

1. The sunburst pattern – shows as a corona effect as the tumor grows outward and pushes the more normal outer bone up and away.
2. A pathologic fracture may be seen through the abnormal bone.
3. Osteosarcoma does not cross the joint space to affect other bones in the joint.

Radiography is almost completely diagnostic in most cases, but there are a few other far less common conditions that can mimic the appearance of a bone tumor, so a confirming test is going to be needed if one is to be complete. If a basic blood panel and urinalysis haven’t been done, this would also be a good time to do so as basic information about liver and kidney function will be needed for treatment regardless of whether this turns out to be a bone tumor or not; plus, a tissue sample from the bone is needed for confirmation (see later).

Tissue Sampling: Biopsy and Needle Aspirate

Radiographs are close to being confirmatory but still they are not definitive. Since life and death decisions are going to be made, it is best to obtain a tissue sample for confirmation. This can be done by either biopsy or by needle aspirate.

Biopsy

A small piece of bone can be harvested surgically. The bone is preserved, sectioned, and examined under the microscope to confirm the diagnosis of osteosarcoma. There are several problems associated with this diagnostic.  Sometimes a bone tumor is surrounded by an area of bone inflammation and it may be difficult to get a representative sample. The tiny hole that results when a core of bone is removed can create a weak spot and the bone can actually break. Even if the procedure goes well, often there is increased pain and lameness for the patient afterwards. With so many potential problems, most specialists have switched to needle aspirate for diagnosis.

Needle Aspirate

With needle aspirate, a large bore needle is inserted into the area of the tumor and cells are withdrawn for analysis. A full core of bone is not removed, just a sampling of cells. This is usually sufficient to confirm osteosarcoma. If there is ambiguity, certain stains can often settle any questions the pathologist may have.

With a Diagnosis Confirmed, Staging is the next Consideration

Some specialists recommend nuclear imaging of the skeleton to identify any spread to other bones, which might also alter recommendations; however, this form of imaging is not readily available.

What if it isn’t Really an Osteosarcoma?

The location and radiographic appearance of the osteosarcoma in the limb are quite classic but there are a few outside possibilities that should at least be mentioned. Only a few other possible conditions cause similar lesions in bone: the chondrosarcoma, the squamous cell carcinoma, the synovial cell sarcoma, or fungal bone infection.

Chondrosarcoma

Chondrosarcoma is a cartilage tumor, possibly not as malignant as the osteosarcoma. The chondrosarcoma generally occurs on flat bones such as ribs or skull bones and is not usually found in the limbs. Still, should a chondrosarcoma occur in the limb, treatment recommendations still include amputation of the affected bone and many of the same treatments as for osteosarcoma.

Squamous Cell Carcinoma

The squamous cell carcinoma is a tumor of the external coating of the bone, called the periosteum. This is a destructive tumor locally but it tends to spread relatively slowly. Again, a bone suspected of malignant tumor should be amputated, and the tissue then analyzed and then treatment adjustments should be made thereafter. The squamous cell carcinoma tends not to arise in the same bone areas as the osteosarcoma; it tends to arise in the jaw bones or in the toe bones.

Synovial Cell Sarcoma This is a tumor of the joint capsule lining. Its hallmark is that it affects both bones of the joint. The osteosarcoma, no matter how large or destructive it becomes, will never cross over to an adjacent bone. Prognosis is much better with amputation with synovial cell sarcoma.

Fungal Bone Infection

Coccidiodes immitis is a fungus native to the lower Sonoran life zone of the southwestern United States. It is the infectious agent of the disease called San Joaquin Valley Fever or just Valley Fever. (More scientifically, the condition is called coccidioidomycosis.)  In most cases, infection is limited to a few calcified lymph nodes in the chest and possibly lung disease. In some rare cases, though, the fungus disseminated through the body and can cause a very proliferative bone infection.

The bone infection of coccidiodomycosis grows rapidly and lacks the lytic lesions that are typical of the osteosarcoma. Other fungi, such as Histoplasma capsulatum, also have potential for bone involvement. Pursuit of this possibility makes sense if you live in an area where these fungi are a concern. Disseminated fungal disease is serious and even though this diagnosis is not cancerous, amputating the limb is most likely going to be necessary.

Treatment of osteosarcoma involves two aspects: treating the pain and fighting the cancer’s spread.

How do we Treat the Pain?

Keep in mind that dogs are usually euthanized because of the pain in the affected bone. Treating the pain successfully will allow a dog to live comfortably and extend life expectancy by virtue of extending comfort.

There are two ways to address the pain: amputatating the limb and palliative radiotherapy (usually combined with periodic bisphosphonate infusion treatments).

For most patients, there is one tumor on a leg and no visible tumor spread in the lungs. These are the patients with the best potential results and they are good candidates for amputation. Patients with a lot of arthritis in the other legs or with tumor spread evident in the chest already are probably not candidates for amputation and it may be more appropriate to keep the leg and simply relieve the pain with radiotherapy.

Amputating the Limb

Since the tumor in the limb is the source of pain, it makes sense that amputating the limb would resolve the pain. In fact, this is true. Removing the affected limb resolves the pain in 100 percent of cases. Unfortunately, many people are reluctant to have this procedure performed because of misconceptions.

• While losing a leg is handicapping to a human, losing one leg out of four does not restrict a dog’s activity level. Running and playing are not inhibited by amputation after recovery from surgery. That said, if the remaining legs are arthritic, the stress on them can pose a mobility issue.
  
• While losing a limb is disfiguring to a human and has social ramifications, dogs are not self-conscious about their image. The dog will not feel disfigured by the surgery; it is the owner that will need to adjust to the dog’s new appearance.
  
• Median survival time for dogs who do not receive chemotherapy for osteosarcoma is 3 to 5 months from the time of diagnosis regardless of whether or not they have amputation. Do you want your dog’s last 3 to 5 months to be painful or comfortable?

Read a letter about amputation from a veterinarian who sees too many owners who reject the option of amputation out of hand. His letter includes videos of two happy dogs without limbs.

Limb-sparing Surgery (removing the tumor but not the leg)
Limb-sparing techniques developed for humans have been adapted for dogs. To spare the limb and thus avoid amputation, the tumorous bone is removed and either replaced by a bone graft from a bone bank or the remaining bone can be re-grown via a new technique called bone transport osteogenesis. The joint nearest the tumor is fused (i.e., fixed in one position and cannot be flexed or extended.)

1. Limb sparing cannot be done if more than 50% of the bone is involved by tumor or if neighboring muscle is involved.
2. Limb sparing does not work well for hind legs or tumors of the humerus (arm bone.)
3. Limb sparing works best for tumors of the distal radius (forearm bone).
4. Complications of limb sparing can include: Bone infection, implant failure, tumor recurrence, and fracture.

While amputation can be viewed as a pain management strategy, limb-sparing is only performed in conjunction with chemotherapy. It is important to keep in mind that grafting of a new bone structure requires healing time and that a great deal of post-operative confinement time is needed (in a patient whose life expectancy is going to be measured in months). For the right patient, limb-sparing can be the best choice but be sure to understand all the details of post-operative care from the specialist.

Palliative Radiotherapy for Pain Control

Sometimes amputation is simply not the right choice and happily there is an effective alternative treatment. Radiation can be applied to the tumor in two, three or four doses, depending on the protocol. Improved limb function is usually evident within the first 3 weeks and typically lasts 2 to 4 months. When pain returns, radiation can be given again for further pain relief if deemed appropriate based on the stage of the cancer at that time.

There are a couple of caveats:

• When pain is relieved in the tumorous limb, there is an increase in activity that can in turn lead to a pathologic fracture of the bone.
•  Radiotherapy does not produce a helpful response in about 1/4 of patients. Remember, amputation controls pain in 100 percent of cases but if amputation is simply not an option, there is a 3 out of 4 chance that radiotherapy will control the pain.

Current standard treatment involves pairing palliative radiation with monthly infusions of medications called bisphosphonates. 

Bisphosphonates

This class of drug has become the standard of care in humans with bone tumors and have been found helpful in managing osteosarcoma pain in dogs as well. Bisphosphonates act by inhibiting bone destruction, which in turn helps control the pain and bone damage caused by the bone tumor. The most common bisphosphonate in use for dogs has been pamidronate, though a new drug zoledronate is taking its place gradually. Treatment is given as an IV drip over two hours in the hospital every 3 to 4 weeks. In humans, an assortment of potential side effects have emerged (fever, muscle pain, nausea all lasting 1 to 2 days in up to 25 percent of patients, renal disease in certain situations, low blood calcium levels, jaw bone cell death); these issues so far have not panned out as problems for dogs and cats. Bisphosphonates are important in managing bone tumor pain in patients that have no undergone amputation.

Analgesic Drugs

At this time there are numerous analgesic medications available for dogs with this tumor. No single medication, however, is a match for the pain involved in what amounts to a slowly exploding bone. A combination of medications is needed to be reasonably palliative and should be considered only as a last resort if amputation or radiation therapy will not be pursued. There are several types of drugs that can be combined.

• Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
  These are anti-inflammatory pain relievers developed for dogs: carprofen, etodolac, deracoxib, meloxicam, firocoxib, and others. These are typically given once or twice daily in tablet form at home. The patient should have good liver and kidney function in order to take medications of this class.
  
• Narcotic Pain Relievers
  While these drugs do not have anti-inflammatory properties, they are well-known analgesics and have been used in an assortment of forms for thousands of years. They are particularly useful in chronic pain because they do not interact negatively with other pain relievers. Drowsiness is a potential side effect.
  
• Miscellaneous Supplemental Pain Relievers
  There are two drugs that have surfaced as adjunct pain relievers for animals with chronic pain: gabapentin and amantadine. Gabapentin works on neurologic pain and is rapidly surfacing in the treatment of arthritis, surgical pain, and other chronic pain states. Amantadine works by reducing what is called wind up, a phenomenon where nerves become sensitized to pain leading to the experience of pain from stimuli that normally do not cause pain.

These different drugs are often given together to create analgesia to the osteosarcoma patient when amputation and radiotherapy are not going to happen. It is important to realize that there is a limit to how much pain relief can be achieved against a bone tumor with only pills. It will not be long before the pain of this tumor, as evidenced by not using the leg, tenderness to the touch, etc., overpowers the effect of oral medications.

How do we Treat the Cancer?

 Osteosarcoma is unfortunately a fast-spreading tumor. By the time the tumor is found, it is considered to have already spread. Osteosarcoma spreads to the lung in a malignant process called metastasis. Prognosis is substantially worse if the tumor spread is visible on chest radiographs, so if you are contemplating chemotherapy, chest radiographs should be taken.

1. Chemotherapy is the only meaningful way to alter the course of this cancer.
2. Young dogs with osteosarcoma tend to have shorter survival times and more aggressive disease than older dogs with osteosarcoma.
3. Elevations of alkaline phosphatase, one of the enzymes screened on a basic blood panel, bode poorly. These dogs have approximately 50% of the survival times quoted below for each protocol.
4. A tumor in the lymph nodes local to the leg being amputated also bodes poorly. In the study by Hillers et. al published in the April 15th, 2005 issue of the Journal of the AVMA, median survival was significantly longer (318 days vs. 59 days) in dogs where the tumor was not evident in local lymph nodes at the time of amputation. 

Cisplatin (given by IV every 3 to 4 weeks for 3 treatments)

1.   The median survival time with this therapy is 400 days.
2.   Survival at 1 year: 30% to 60% 
3.   Survival at 2 years: 7% to 21%
4.   Giving less than 3 doses does not increase survival time (i.e., if one can only afford one or two treatments, it is not worth the expense of therapy)
5.   Cisplatin can be toxic to the kidneys and should not be used in animals with pre-existing kidney disease.

Carboplatin (given by IV every 3 to 4 weeks for 4 treatments)

•   Similar statistics to cisplatin but carboplatin is not toxic to the kidneys and can be used if the patient has pre-existing kidney disease.
•   Carboplatin is substantially more expensive than cisplatin.

Doxorubicin (given IV every 2 weeks for 5 treatments)

1.   The median survival time is 365 days.
2.   10% still alive at 2 years.
3.   Toxic to the heart. An ultrasound examination is needed prior to using this drug as it should not be given to patients with reduced heart contracting ability.

Doxorubicin and Cisplatin in Combination (both given IV together every 3 weeks for four treatments)

•   48% survival at 1 year
•   30% survival at 2 years
•   16% survival at 3 years. 

What is Median Survival Time? 

There are a number of ways to statistically evaluate the central tendency of a group. The median is the value at which 50% of the group falls above and 50% of the group falls below. This is a little different from the average of the group, though more people are familiar with this term. When evaluating median survival times, you are looking at a 50% chance of surviving longer than the median and a 50% chance of surviving less than the median. 

What Does Chemotherapy Put my Dog Through?

Most people have an image of the chemotherapy patient either through experience or the media and this image typically includes lots of weakness, nausea, and hair loss. In fact, the animal experience in chemotherapy is not nearly as dramatic. After the pet has a treatment, expect 1 to 2 days of lethargy and nausea. This is often substantially helped with medications like Zofran, a strong anti-nausea drug commonly used in chemotherapy patients. These side effects are worse if a combination of drugs is used but the pet is typically back to normal by the third day after treatment. Effectively, you are trading 8 days of sickness for 6 to 12 months of quality life. Hair loss is not usually a feature of animal chemotherapy. In dogs, hair loss may occur in breeds that have continuously growing coats, such as poodles, Scottish terriers, and Westies. 

Axial Osteosarcoma

While osteosarcoma of the limbs is the classical form of this disease, osteosarcoma can develop anywhere there is bone. “Axial” osteosarcoma is the term for osteosarcoma originating in bones other than limb bones, with the most common affected bones being the jaws (both lower and upper). Victims of the axial form of osteosarcoma tend to be smaller, middle-aged, and females outnumber males two to one.

In the axial skeleton the tumor does not grow rapidly as do the appendicular tumors, thus leading to a more insidious course of disease. The tumor may be there for as long as two years before it is formally diagnosed. An exception is osteosarcoma of the rib, which tends to be more aggressive than other axial osteosarcomas.

Treatment for axial osteosarcoma is similar to that for the appendicular form: surgery followed by chemotherapy. There is one exception, that being osteosarcoma of the lower jaw. Because of the slower growth of the axial tumor and the ability to remove part or all of the jaw bone with little loss of function or cosmetic disfigurement, it has been reported that 71% of cases survived one year or longer with no chemotherapy at all.

Additional information can be found at Bone Cancer Dogs, Inc., a nonprofit corporation.

Not all veterinarians are comfortable treating osteosarcoma. Discuss with your veterinarian whether referral to a specialist would be best for you and your pet.

1. Pain in the jaw joints as well as in the gums, lips, cheeks, and teeth.

Genetic or Not?

Occlusion is the way in which teeth align with each other. Occlusion is controlled by genetics, nutrition, environment, and by mechanical forces generated by the interlock of the upper and lower teeth. Some abnormal bites (malocclusions) are genetically influenced, such as severe over or under bites and wry bites. Other bite abnormalities are known to be acquired (non-genetic). Acquired malocclusions can result from tug of war games played with towels or ropes that move teeth into an abnormal position. Traumatic birthing can also be responsible for some acquired abnormalities.

To help define whether the malocclusion is genetic in origin, interdigitation of the premolars is studied. In breeds that have medium and long muzzles, the premolars should meet in a saw toothed fashion. For example, the tip of the lower third premolar should be positioned equally between the crowns of the upper third and fourth premolars. If the tip of one premolar points to the tip of another premolar, there may be a genetically-induced malocclusion. This only holds true in breeds that do not have shortened muzzles.

Some genetic bite problems do not show up in each litter because they are passed on recessively. The goal of selective breeding is to mate one animal to another that has superior occlusion.

Retained Deciduous Teeth

Normally the root of the deciduous (baby) tooth is reabsorbed, making room for an adult tooth. Should this fail, the adult tooth may move from its normal position, resulting in malocclusion. The resulting double set of teeth overcrowds the dental arch, causing food to become trapped between the teeth, which lead to early periodontal disease. A double set of roots may also prevent normal development of the socket and erode periodontal support around the adult tooth, resulting in early tooth loss. A retained deciduous tooth should be extracted as soon as an adult tooth is found in the same area as the baby tooth. If the extraction is performed early, the abnormally positioned adult tooth usually moves to its normal location.

Some breeders trim or cut deciduous teeth in the hope that they will be shed early and prevent orthodontic problems. When the tooth is cut in half, pulp is exposed to oral bacteria causing infection, pain, and tooth loss. Unfortunately, the remaining infected root can interfere with the emerging adult tooth, which may not come in normally.

Dental Interlock

Jaws do not grow at equal rates. If deciduous (baby) teeth erupt during an accelerated growth phase of one jaw, both sets of primary teeth can interlock and result in an abnormal bite. Even genetically normal dogs can occasionally develop abnormal bites due to the interlock of primary teeth. If an under bite is noted before the permanent teeth erupt, treatment may be helpful. Removing the primary teeth (from the shorter jaw) that are interfering with the forward jaw growth may allow the upper jaw to lengthen unimpeded, if the procedure is performed by 10 weeks of age. This procedure, called interceptive orthodontics will correct about 50% of minor jaw length malocclusions by the time permanent teeth erupt. Extracting teeth does not stimulate jaw growth; it only removes a mechanical barrier to genetic control of the growth process.

Breeders, show judges, veterinarians, and others who wish to describe specific dental conditions in dogs and cats should use proper orthodontic terms. Over bite, open bite, over jet, level bite, overshot, under bite, anterior cross bite, posterior cross bite, wry bite, and base narrow canines are orthodontic terms that are confusing at times.

Missing or Extra Teeth

Dogs and cats may be born without the proper number of teeth. The overcrowding from extra (supernumerary) teeth can cause periodontal disease. The American Kennel Club sets acceptable standards for show dogs about the minimum number of teeth for each breed. Dental x-rays can be taken as early as 10 weeks of age to evaluate if the dog has the correct number teeth. X-rays are recommended as a part of the prepurchase examination in certain breeds. Missing teeth (hypodontia) usually occur in the premolar area, but any tooth in the mouth may not erupt. Missing or extra teeth are considered genetic faults. Collies and Doberman Pinchers are most commonly affected. Sometimes the missing tooth is trapped below the gum line, and a dental x-ray can be taken to determine if there is an unerupted tooth.

Misdirected Canine Syndrome

Misdirected canine syndrome is a bite abnormality where retention of the deciduous (baby) tooth tilts the erupting permanent canine tooth into an abnormal location. The opposing canines may not have room to occlude properly, resulting in abnormal wear, periodontal disease, or early tooth loss.

Occlusion

The way in which teeth align with each other is called occlusion. Normal occlusion in most medium and long muzzled breeds consists of the upper (maxillary) incisors that just overlap the lower (mandibular) incisors (scissors bite). The lower canine should be located equidistant between the corner (lateral) incisor and the upper canine tooth. Premolar tips of the lower jaw should point between the spaces of the upper jaw teeth.

Malocclusion

Malocclusion refers to an abnormal tooth alignment. Over bite (mandibular distoclusion, parrot mouth, over shot, class two, over jet, mandibular brachygnathism) occurs when the lower jaw is shorter than the upper. There may be a gap between the upper and lower incisors when the mouth is closed. The upper premolars are displaced at least 25% toward the front compared to the lower premolars. An over bite malocclusion is not considered normal in any breed and is a genetic fault. The most commonly affected breeds are those with elongated muzzles (Collies, Shelties, Dachshunds, and Russian Wolfhounds).

An underbite (mandicular mesioclusion, under shot, reverse scissors bite, prognathism, class III) occurs when the lower teeth protrude in front of the upper jaw teeth. Some short-muzzled breeds (Boxers, English Bull Dogs, Shih-Tzus, and Lhasa Apsos) normally have an under bite, but it is abnormal when it occurs in medium-muzzled breeds. When the upper and lower incisor teeth meet each other edge to edge, the occlusion is considered an even or level bite. Constant contact between upper and lower incisors can cause uneven wear, periodontal disease, and early tooth loss. Level bite is considered normal in some breeds, although it is actually an expression of under bite.

Rostral cross bite occurs when canine and premolar teeth on both sides of the mouth occlude normally, but one or more of the lower incisors are positioned in front of the upper incisors. This condition can be caused by tug-of-war games, retained primary teeth, or impacted roots. Anterior cross bite is a common malocclusion. It is not considered a genetic or inherited defect. Posterior cross bite occurs when one or more of the premolar lower jaw teeth overlap the upper jaw teeth. This is a rare condition that occurs in the longer nosed dog breeds. A wry mouth or wry bite occurs when one side of the jaw grows more than the other.

Wry bites show as triangular defects in the incisor area. Some of the incisors will meet their opposing counterparts while others will not. Wry bite is a severe inherited defect. Base narrow canines occur when the lower canine teeth protrude inward, often producing damage to the upper palate. This condition is either due to retained deciduous teeth, or by an overly narrow mandible. Base narrow canines may be corrected through orthodontic devices that push the teeth into normal occlusion. An open bite occurs when some incisors are displaced vertically and do not touch.  The tongue will often protrude.

Rotated teeth, commonly affecting the upper third premolar, occur mostly in short-muzzled breeds. Selective breeding has created undersized mouths that cannot accommodate 42 teeth in normal alignment. The rotated tooth root closest to the palate is prone to periodontal disease. Strict tooth brushing may be helpful in saving a rotated tooth, but frequently it cannot be saved.

Orthodontic Care

Many abnormal bites can be corrected. Orthodontic care should be performed by veterinarians familiar with tooth movement principles. Sometimes breeders use rubber bands to move teeth but they compromise the gum tissue around teeth, leading to periodontal disease, pain, and early tooth loss. Orthodontic care should be reserved to ease pet discomfort by realigning teeth in those animals that will not be used for show. Tooth movement is accomplished by employing brackets, acrylic retainers, springs, and elastics. Fortunately, in animals orthodontic movement can usually be accomplished in months rather than years.

If your dog’s or cat’s teeth do not appear to meet normally, have your veterinarian take a peek and make recommendations to help your pet.