It has been said that the treatment of heartworm infection is something of an art. There are several strategies that can be used depending on the dog’s medical condition, including the option of not treating at all. The important concept to realize is that, while there are off label alternative heartworm-killing protocols, the FDA-approved method of killing adult heartworms involves very harsh arsenic-based drugs and killing large adult heartworms is neither simple nor safe. Let’s review some of the dangers and options in clearing the body of this parasite.

Patient Evaluation

Prior to therapy, the heartworm patient is assessed and rated for risk into one of four categories. Important factors include: how many worms are thought to be present based upon the tests performed, the size of the dog, the age of the dog, concurrent health factors, severity of the heart disease, and the degree to which exercise can be restricted in the recovery period. Some hospitals use computerized formulas to categorize heartworm infected patients. The categories into which patients are grouped are as follows:

Class I: Lowest Risk. These dogs are typically without symptoms and their infection is a surprise discovery during a routine annual health examination when a positive test comes up. Other blood tests are normal and radiographs show mild changes if any change at all.

Class III: Severely Affected. Dog is suffering from weight loss, cough, difficulty breathing, and blatant damage to the vasculature is apparent on radiographs; lab work reveals a more severe anemia and marked urinary protein loss. The damage to the lung blood vessels from the worms creates extra resistance for the heart to pump against, and often, episodes of collapse occur with exercise. 

• Class IV: Caval Syndrome. Dog is collapsing in shock with dark brown urine evident. Heartworms are visible by ultrasound in the AV valve of the right side of the heart, with very abnormal bloodwork. These dogs are dying and can only be saved by the physical removal of adult heartworms via an incision through the jugular vein. If such a dog can be saved from this crisis, further treatment cannot be contemplated until the dog is stable enough to fit into one of the other categories above. In this video (we warn you this is not for the faint of heart), view the physical removal of adult heartworms from the jugular vein of a dog with caval syndrome.

After knowing what class the patient fits in, treatment can be determined. The dog has three groups of heartworms in their body: microfilariae (basically newborn worms whose parents are living inside the dog in question), newly arrived immature worms (relatively fresh from the mosquito bite and living in the skin tissues), and adult worms themselves.  

• Microfilariae are the first stage larvae (basically the youngest stage). These are the children of the adult worms living in the heart and blood vessels. The mother worm gives live birth (no eggs involved) and the babies swim freely in the host’s bloodstream. They must be killed so that they cannot be picked up by mosquitos and transmitted to new dogs..

The newly arrived heartworm larvae, freshly delivered from mosquito bites in the last 3 months. These are third and fourth stage larvae living in the skin. For practical purposes, we will include the L5 larvae in this group. The L5’s are old enough to leave the skin tissues and enter the circulation but they are not really mature enough to be called adults. This group of young worms (L3’s and L4’s in the skin and L5’s in the circulation) represent the first 5-7 months of infection. We need to kill them before they reach maturity and begin to wreak havoc on the cardiovascular system of the host.

Stabilization First

Killing the Microfilaria and Migrating Worms 

The next step in treatment is clearing the migrating immature worms. Heartworm treatment is a project that lasts at least a couple of months. We do not want immature worms to mature in that time frame. Since our goal is to have fewer adult worms when the time comes to kill the adult worms, it behooves us to kill the younger worms right off the bat.

The tissue-based L3 and L4 larvae are killed by monthly macrocyclic lactone-based heartworm preventive products (avermectins and milbemycin). Killing the L3 and L4 larvae prevents heartworm infection. Some of these products can also kill circulating microfilariae (which need to pass through a mosquito before becoming infective to other animals).  The only FDA-approved product for killing microfilariae after adulticide therapy is Advantage Multi®, which contains moxidectin. Other products can be used for this purpose also, but it should be noted that an anaphylactoid reaction can occur if a large number of microfilariae are killed rapidly with products such as high-dose ivermectin (off-label) or high-dose milbemycin (e.g., Interceptor). This problem has not been noted with Advantage Multi. While low-dose ivermectin products (e.g., Heartgard) will gradually eliminate microfilariae in most dogs, the package insert discourages it for this use.

Killing Wolbachia

Wolbachia is a genus of rickettsial organisms (sort of like bacteria, but not exactly) that live inside heartworms of all developmental stages, but their numbers begin to expand once the young worms reach their infectious stage. Wolbachia organisms seem to be protective or beneficial to the heartworms that harbor them, aiding in metabolism and general worm health. Without Wolbachia colonization, many female worms are not able to reproduce, and third-stage larvae are not able to infect new hosts. 

Wolbachia organisms possess inflammatory surface proteins that are released when adult worms die or are killed in treatment, and these proteins greatly increase the chances of severe circulatory reactions in the canine host.

It has been found that killing Wolbachia with an antibiotic such as doxycycline is helpful in treating the heartworm infection as the Wolbachia can be removed from their heartworm hosts, thereby weakening the worm and minimizing the release of inflammatory proteins when the worm finally dies. To minimize reactions, the American Heartworm Society recommends using doxycycline along with heartworm preventives for a good month as soon as the diagnosis is made and prior to the use of the arsenic compounds needed to kill the adults.

Killing the Adult Worms

he only product currently available for treating adult heartworms is melarsomine dihydrochloride (Immiticide^® or Diroban^®. If you go by the manufacturer’s recommendations, treatment can be done in two or three doses, depending on the class of heartworm infection. Most universities, however, opt to treat all patients with the three-dose protocol as it creates a more gradual kill of the adult worms (which is safer in terms of embolism and shock).

The patient receives an intramuscular injection deep in the lower back muscles. This is a painful injection with a painful substance, and it is common for the patient to be quite sore at home afterward. Pain medication may be needed. Be careful around the injection site, as the pet may bite. The site may form an abscess that requires warm compresses. Approximately 30% of dogs experience some injection site reaction. These generally resolve in 1-4 weeks. 

In the two-dose protocol, the dog returns for a second injection the next day on the opposite side of the lower back. In the three-dose protocol, the dog comes back one month later for two doses 24 hours apart (the first dose is an introductory treatment to kill some of the more sensitive worms.) Keep in mind that too many worms dying at once creates circulatory shock. The benefit of the three-dose protocol (sometimes called the split dose protocol) is that the first injection serves to kill off any older or weaker worms without killing off the stronger, younger ones. When the two consecutive doses occur one month later, there will be fewer worms dying at once.

After treatment, the patient must be strictly confined for one month following the final treatment. No walks, no running around. The dog must live an indoor life. The reason for this is that embolism, to some degree, is inevitable, and it is important to minimize embolism-related problems. Exercise increases heart rate and oxygen demand, and we need the heart to rest during this recovery period.

Watch for:

• Coughing
• Fever
• Nose bleeds

If any of these occur, report them to the vet as soon as possible. The most critical time period is seven to 10 days following a melarsomine treatment, but these signs can occur anytime in the following month.

The “Slow Kill Method” with Ivermectin Only

Melarsomine treatment is expensive and often out of reach for rescue groups, shelters, and many individuals. If the dog is stable (Class I), one option is to simply leave the dog on an ivermectin-based preventive. This option has led to a great deal of misconception about the ability of ivermectin to kill adult heartworms.

Let us lay the rumors to rest now:

1. Ivermectin does not kill adult heartworms.
2. Ivermectin does shorten the lifespan of adult heartworms.
3. Ivermectin does sterilize adult heartworms.
4. Ivermectin does kill microfilaria (keeping the dog from being a source of contagion)
5. Ivermectin does kill L3 and L4 larvae (preventing new infections).

This means that if you opt to treat a heartworm-positive dog with only an ivermectin heartworm preventive, you can expect the dog to remain heartworm-positive for as long as two years and the heartworm disease will be progressing during that time. This is not good for the dog but certainly beats getting no treatment of any kind.

The “Slow Kill Method” with Mox-Dox 

Adding doxycycline to ivermectin has changed the way slow kill works. As the “slow kill” protocol evolved, topical moxidectin has been substituted for ivermectin, and a month of twice daily doxycycline is used to kill the Wolbachia bacteria that are so protective of the living heartworms. The result seems to be a much faster slow kill with microfilaria clearing three weeks or so (addressing the resistance in microfilaria issue of slow kill). The adult worms die over 3-4 months, which is similar to the 3-dose protocol (1-3 months on preventive, one dose of melarsemine with two doses following a month after that).

Exercise restriction is still needed, and relatively high doses of moxidectin are also needed. (The topical product is essential; long-acting injectables wane too quickly). Heartworm antigen testing is performed nine months after starting the protocol and continued monthly until negative. If the dog is still heartworm antigen positive after 15 months, new decisions should be made (do mox-dox again, use melarsomine, etc.) The American Heartworm Society views this protocol as a salvage procedure, meaning that it could be considered for a dog for whom melarsomine is not an option. Research and controversy continue with regard to this method.

The goal in long-term management of diabetes mellitus is the alleviation of unpleasant clinical signs (constant thirst, weight loss, etc.) and the prevention of dangerous secondary conditions (infections, ketoacidosis, etc.). To accomplish this, blood sugar levels should be regulated between 250 mg/dl (13.88 mmol/L) and 80 mg/dl (4.44 mmol/L). This is not as good as the body’s natural regulation, but it is a fair and achievable goal in most cases.

Some patients just seem completely unaffected by even high doses of insulin, and it is important to have a step-by-step plan to rule out causes of insulin resistance so that regulation can be achieved.

Insulin resistance is defined as:

Persistent high blood sugar levels throughout the day when three units of insulin per four pounds of patient body weight are used.

or

A unit or more of insulin per pound of patient body weight (or more) is needed to achieve regulation.

This may seem basic, but it is important not to skip the basics. Confirm that the amount of insulin being drawn into the insulin syringe is correct, that the injection technique is correct, and that the patient is actually receiving the injection. Rule out any snacking or changes in the patient’s feeding schedule. Be sure the bottle of insulin is not expired and that it has been properly stored. Ideally, the veterinary staff will observe insulin administration and will check the bottle while the pet is being checked in the hospital.

Review insulin storage and handling.

Step Two: Determine for sure that the Patient is Insulin Resistant

A glucose curve is needed to distinguish the following three phenomena.

Somogyi Overswing

In the case of Somogyi overswing, the insulin dose is too high and drives the blood sugar low for part of the day. When the blood sugar is low, other hormones such as cortisone or adrenalin are released to raise blood sugar. These hormones can have a prolonged effect (many hours), thus creating hyperglycemia (high blood sugar). If the patient’s high blood sugar has been caused by a Somogyi overswing, a lower dose should be used and a new curve performed in a week or two. One might think a flat glucose curve (i.e. one not showing hypoglycemia followed by hyperglycemia) would rule out Somogyi overswing but, in fact, a Somogyi hyperglycemia can persist for days and create a flat curve. Often a good approach is to cut the insulin dose back and see what the curve looks like.

Rapid Insulin Metabolism

In this case, the insulin simply is not lasting long enough to create sustained normal blood sugar levels. If the curve shows that the insulin effect is wearing off too soon, twice a day administration of the insulin may solve this problem or a longer-acting insulin may be needed. Longer acting insulins tend to have poorer absorption into the body from an injection site. This may also necessitate change to a different insulin type. Often it is necessary to change to a human insulin from a canine insulin.

True Insulin Resistance

Here no significant drop in blood sugar level (levels stay greater than 300 mg/dl[16.65 mmol/L]) is seen in response to the insulin dose used. Usually there is a history of prior increases in insulin dose, all met with minimal response.

Step Three: Spay

Hormone fluctuations will easily account for insulin resistance as progesterone is one of many hormones that raise blood sugar levels (by stimulating growth hormone secretion). Canine unspayed female diabetics need to be spayed if regulation is to be achieved. (Feline patients do not have a similar relationship with naturally occurring progesterones and do not require spaying; however, progesterone-type medications can produce diabetes in cats. Diabetic patients of either species should not take progesterone-related medications.)

Step Four: Rule out Infection

Diabetic animals are at risk for developing bladder infections because they have so much sugar in their urine. Stress of any kind will contribute to high blood sugar and infection would lead to stress. A urine culture should be done to rule out bladder infection, plus the teeth and skin should be inspected for infection in these areas. If infection per se is not found, the patient should be screened for other chronic illnesses that might constitute a stress. A basic blood panel would be a logical starting point.

If infection or other stress is allowed to go unchecked, ketoacidosis, an especially life-threatening complication of diabetes mellitus, can develop.

To avoid infection issues, it is a good idea to plan for diabetic patients to have their teeth cleaned annually and to have the urine periodically cultured whether there are symptoms of a problem or not.

Step Five: Control Obesity

Insulin response is typically blunted in obese patients. If obesity is an issue, it should be addressed. A formal weight loss program using measured amounts of a prescription diet and regular weigh-ins is necessary for success. See general information about weight loss for pets. If these steps do not reveal a relatively simple explanation for the poor insulin response, then it is time to seek more complicated causes. This generally means an additional hormone imbalance.

Hyperadrenocorticism (Cushing’s Disease)

This condition is relatively common in dogs but less so in cats. This condition involves an excess in cortisone-type hormones, either from over-production within the body or over-treatment with medication. Cortisone – more accurately referred to as cortisol – is secreted naturally in response to a fight or flight situation and prepares the body for exercise by mobilizing sugar stores. If sugar is mobilized into the blood stream in the absence of a fight or flight situation, diabetes mellitus can result. If the excess cortisone situation is resolved, it is possible that the diabetes will also resolve.

About 10% of dogs with Cushing’s disease are also diabetic. About 80% of cats with Cushing’s disease are also diabetic. Testing for Cushing’s disease cannot proceed until some degree of diabetic control has been achieved and the patient is not ketoacidotic.

Excess Circulating Lipids

High levels of circulating triglycerides (fats) interfere with binding insulin to the cells it needs to act upon. While most dogs with excess circulating lipids are not diabetic, when a diabetic patient is insulin resistant it may be helpful to attempt to reduce the circulating fats. Excess lipids in the blood usually occur because of some other hormone imbalance (Cushing’s disease, hypothyroidism in dogs etc.) but they can simply happen spontaneously in the miniature schnauzer.

Circulating fats are reduced by treating the hormone imbalance that caused them if there is one. If there is no underlying disease, circulating lipids can be reduced with diet and omega 3 fatty acid supplementation.

Acromegaly

Acromegaly results from an over-secretion of the pituitary hormone known as growth hormone. This hormone normally is responsible for one’s growth from infancy to adulthood. When adulthood is achieved, its secretion dramatically slows, bone growth plates close, and growth essentially stops. If for some reason, this hormone begins secreting again, growth resumes but not generally in normal proportions as the limb bones have closed their growth areas.

One of the effects of growth hormone is causing the body tissues to become resistant to insulin by interfering with tissue insulin receptors. Animals with acromegaly are frequently diabetic.

The prognosis and treatment for acromegaly is different between dogs and cats. Dogs generally develop acromegaly due to excess progesterone secretion, as would occur from an ovarian cyst. Canine patients are thus usually older, unspayed females and spaying may be curative depending on the remaining ability of the pancreas to secrete insulin.

Antibodies against Insulin

When a patient is treated with insulin from another species, the immune system recognizes the introduction of the foreign protein and generates antibodies. It was because of this phenomenon that most commercial insulin available is genetically engineered human insulin so that the world’s human diabetics no longer need to worry about making insulin antibodies.

But where does this leave dogs and cats? It leaves them making antibodies against human insulin, that’s where. There is no feline insulin product available; the closest thing is beef insulin. Dogs are luckier as their insulin is identical to pig insulin and porcine insulin is available as Vetsulin® (Caninsulin® in Canada). If a human insulin is used, some degree of antibody production is a forgone conclusion.

You would think this would pose a big problem but in fact insulin antibodies are not always bad. Most of the time the antibodies simply interfere with removal of the insulin, leading to a longer-acting insulin than would be achieved with the same type of insulin made from the native species. For example, Humulin N® (human insulin) will last longer in the dog than Canine Insulin N (if there were such a product). This may be desirable depending on the patient; changing the species of origin of the insulin is one way to get the insulin to last a bit longer.

To become insulin resistant from antibodies, a body must lose 70% or more of the insulin injection to antibody binding. This is very unusual but possible and should not be forgotten as a possible cause of insulin resistance. Blood tests to measure insulin antibodies are available in some areas. Insulin can be switched to a species of origin more closely related to the species desired.

If a Cause Cannot be Found

If a cause cannot be found or if treatment for that cause is not practical or possible, the good news is that multiple high doses of insulin can generally overcome the resistance. Sometimes combinations of short and long-acting insulins are used together to achieve reasonable regulation.

Whether the patient is a dog or a cat, ovarian remnant syndrome is suspected when a spayed female pet appears to be coming into heat, something that should be impossible after spaying. A spayed female has had both her ovaries removed and should not cycle and should not display behaviors typical of heat. If she is displaying signs of an active heat cycle, a search for an estrogen source is required. In particular, we need to rule out the presence of a piece of ovarian tissue left inside. If a piece of ovary (or similarly active tissue) is indeed inside, the only treatment is surgically removing it, and since this is an invasive solution, we want to be as certain as possible that there is no other likely explanation.

The Girl Dog in Heat

The Girl Cat in Heat

A female cat in heat does not have an apparent vaginal discharge. For her, the signs of heat are more behavioral. She becomes restless and loudly vocal. She may urinate in the house in an attempt to notify local tomcats of her state. She is often unusually affectionate and has a tendency to stick her rear in the air and even tread her feet when she is petted over her back.

A female cat cycles seasonally, when the days are longer, and tends to stop cycling when the days begin to get shorter. She is in heat for five days or so and then out of heat for a couple of weeks, then back in, then back out over and over until she is either bred or the seasons change. If she is bred, she will ovulate and go into a false pregnancy or a real one if the breeding was successful. In any case, it is the behavior that is the clue that her hormones are active, especially since the occasional female cat will not follow the usual rules about the seasons.

Signs of heat (also referred to as estrus) imply estrogen in the pet’s system. The first step is to confirm that there genuinely are estrogens in her system.

Testing for Hormones

Vaginal Smear

You might expect a blood test to be necessary to look for estrogen or progesterone, but in fact, the best test is a vaginal smear test, at least for dogs. Using a cotton swab, the veterinarian harvests some cells from the vaginal wall and looks at them under the microscope. If the female is in heat at the time of the test, the cells will have a characteristic appearance called cornification. This means there are estrogens in her body.

Blood Testing

Testing for estradiol, one of the estrogen hormones, can be done but is not as accurate as the vaginal smear test. If the spayed female has high estrogen levels during the time she appears to be in heat, this would be considered a positive test. The problem is that low levels can still be present in the bloodstream even if there is an ovarian remnant, so low levels are hard to interpret.

Another approach is to give her a shot of GnRH (gonadotropin releasing hormone) while she appears NOT to be in heat. If she responds to the injection by producing progesterone two weeks later (detectable with a blood test), this would be consistent with an ovarian remnant.

The vaginal smear costs a fraction of the amount of blood testing and can generally be done in a matter of minutes in the doctor’s office, so these types of blood tests are rarely performed.

Witness LH and SpayChek® Testing

There is an in-house test kit for luteinizing hormone (LH) that can determine if a female cat or dog has been spayed or not, provided she is not experiencing a heat at the time of the test. This test could be performed to assist in diagnosis but would have to be done during a time without symptoms of heat. A low LH level is compatible with the presence of estrogen and presumably ovarian tissue.

The newer SpayChek® test for anti-mullerian hormone is reportedly more reliable but requires that at least two to three months have passed since the original spay surgery for accuracy. It is best performed in conjunction with a progesterone level for the best accuracy.

Your veterinarian may suggest more than one type of test to be sure there is little room for ambiguity. After it is clear that estrogens are definitely present, the next question to address is, “Where did they come from?”

Where Did they Come from?

Estrogen Creams for Human Use

Topical estrogen-containing creams have numerous human uses. These creams invariably end up on the user’s hands or arms, where a loving pet can lick them. A female pet exposed to a hormone crème in this way can easily manifest signs of heat but will not show a hormone cycle in any predictable way. Generally, people are aware that hormone crèmes are in use at home and can be more careful about avoiding exposure to pets. Creams may be applied using gloves that can be discarded away from the pet, hands can be washed carefully, etc.

original spay surgery was performed months or even years before. These secondary bits of ovary are growing in this time and do not show themselves until they have achieved sufficient hormone-producing power. Once it has been determined that a pet has an ovarian remnant, surgery should be performed to locate and remove it.

It is worth mentioning that adrenal tumors can produce hormones. These can be difficult, if not impossible, to remove, but exploratory surgery should at least identify them over an ovarian remnant. In the situation of this type of tumor, signs of heat are constant; they do not cycle as with ovarian tissue.

Treatment

The ovarian tissue will be most prominent or visible just following the active heat period. This is the time after ovulation when the ovary is normally ripe with large progesterone-secreting structures called corpora lutea, and this is the best time for surgical exploration. If errant ovarian tissue is found, it can be removed generally without difficulty. It is not unheard of, however, for the ovarian remnant or remnants to be impossible to find. If that is the case with your pet, Discuss with your veterinarian whether referral to a surgical specialist would be best for you and your pet; however, a surgery specialist may be necessary to find the remnants. Biopsy of the removed tissue should settle the question as to whether the hormone source was removed intact or not.

Why Do We Need to do Anything at all?

The problem with all this is not limited to the inconvenience of hormone-related behaviors and discharges. The actual problem is that hormones can cause harm. Long-term exposure to female hormones can promote mammary cancer. If a small piece of uterus persists after spaying, the influence of female hormones can promote chronic infection (“stump pyometra”). While neither of these outcomes is definite, their repercussions are serious, and it is best to take these hormones out of play.

What if it isn’t Heat?

Female dogs can have a bloody vaginal discharge for reasons other than heat. It is possible the owner is seeing bloody urine, for example, and the medical workup will need to shift to address the different causes of this problem. Alternatively, a transmissible venereal tumor, urinary tract infection, or vaginal injury might lead to bleeding.

As for a female cat, she may simply have behavioral issues to address.

Hypertrophic osteodystrophy is a developmental, auto-inflammatory disease of the bones that is usually first seen between 7 weeks and 8 months of age.  In general, most cases will appear for the first time when the puppy is between 3 – 5 months of age. Relapses may occur until about 20 months of age.

HOD is most often seen in fast-growing puppies of large and giant breeds.

Some medium-sized breeds, such as the Australian cattle dog and pit bull may also develop HOD. The Weimaraner, in particular, appears to be predisposed to HOD.

• Large breed dogs
• Rottweiler
• Saint Bernard
• Standard poodle
• Weimaraner

In HOD, blood flow decreases to a part of the bone next to the joint. This interrupts bone formation. The interruption means that bones don’t harden appropriately, nor do they grow as strong as those of a healthy puppy.

HOD can be very painful. Sometimes HOD is straightforward and responds quickly to treatment, but it can also be tricky to diagnose and treat.

HOD is somewhat similar to panosteitis (pano) in that it affects the growing leg bones of large- or giant-breed puppies. However, pano usually affects only one leg at a time, and is thought of as “growing pains.” HOD can affect more than one leg at the same time and is more painful than panosteitis. In addition, unlike pano, HOD can permanently damage the growth plates.

HOD doesn’t appear to be inherited, and at this time no one knows how puppies get it, although auto-immune diseases and dietary excesses can trigger it. However, because it is more common in some breeds if the puppy is being considered for breeding purposes, your veterinarian may recommend a thorough review of the pup’s relatives, to see how many of them have had HOD. If the puppy comes from a bloodline that has few cases, or the cases were mild and self-limiting, that may be better for breeding purposes than bloodlines that have had many cases, or have severe cases. (Every pup, of every breed, being purchased for breeding purposes should always have an extensive review of the relatives, to avoid known breed-related issues.)

Clinical Signs

Clinical signs depend on how mild or severe the HOD is. For mild cases, the puppy usually has a slight limp and appears to have pain in the affected bone. Puppies with more severe cases may have a decreased appetite and subsequent weight loss, fever, and depression. Unfortunately, these non-specific signs can happen with many diseases.

More specific signs of HOD include swollen, warm, and painful leg bones. The puppy may refuse to bear weight. If multiple limbs are affected, the puppy may prefer to remain lying down, be reluctant to get up, and be unwilling to walk.

And not just the legs may be involved. Some cases have swollen muzzles, excessive salivation, and pain when the dog tries to open his mouth; these cases may involve the jaw. Also, radiographs may show changes in the jaw, spine, ribs, shoulder, and eye socket bones.

Systemic signs can include:

1. Fever ranging up to 106⁰F (a dog’s normal body temperature is 101-102.5⁰F)
2. Lack of appetite
3. Discharge from the eyes or nose
4. Bumps on the skin, some with pus
5. Diarrhea that can be bloody
6. Inflamed vulva or vagina
7. Increased respiratory sounds

At the very least, HOD dogs will have a fever, lameness, and typical HOD lesions showing on the radiographs. The more signs the puppy has, the more severe the case. (In severe cases, with multiple systems and organs affected, more aggressive treatment to suppress the immune system will be necessary.)

A complicating factor to remember is that, for the most part, HOD patients are very young puppies that do not have bodily reserves and can decline rapidly with fever and lack of appetite.

HOD can be a painful condition and typical treatment to control even significant pain may not work.

HOD generally comes in episodes that last a few weeks. Often the first episode lasts a week and it can be followed by a full and spontaneous remission.

Diagnosis

Diagnosis is made via physical exam (seeing obviously swollen soft tissue over the leg bones), radiographs, blood tests, etc.

Treatment

Your veterinarian will want to control the fever, lethargy, and bone pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) are often used for this. However, if the puppy develops gastrointestinal signs, the NSAIDs may have to be discontinued.

Some puppies may need immunosuppressive doses of corticosteroids, usually prednisone. Some dogs may need to take them for a year, in which case the drug must be tapered off slowly, rather than simply stopped. Your veterinarian will recommend tapering only once the dog is free of pain and walks normally.

In some cases, narcotics may be necessary to control severe pain. These may have to be given by intravenous injection.

Some breed-specific studies have shown better responses to corticosteroids than to NSAIDs. In one study of 53 Weimaraners, 50 percent did not respond to NSAIDs. In another study of six related Weimaraners, NSAIDs had little effect and the dogs had to be switched to corticosteroids. A similar experience has been reported in affected Irish setters and Australian kelpies.

Your veterinarian may need to prescribe antibiotics for pneumonia or to prevent secondary infections resulting from immune systems that have been depressed by the corticosteroids. Antacids, such as famotidine, may be given while the dog is taking the corticosteroids. Some veterinarians may recommend probiotics when the GI tract is involved. Pain medications may be needed.

Other care may include fluid therapy, analgesics (e.g. tramadol, opiates), and rest or restricted activity. Even when the puppy starts feeling better, the veterinarian may still want exercise to be restricted until the bones have structurally recovered.

Vaccines should be avoided during an active HOD episode.

Monitoring and Prognosis

Mild cases of HOD may resolve on their own or with only supportive care. Watch for a possible return of any clinical signs once the dog has stopped/tapered the NSAIDs or prednisone because recurrences are common until the leg bone has finished growing. Dogs with affected litter mates are more likely to relapse. Complete recovery is expected once the leg is finished growing, but relapses (episodes of fever and malaise) have been reported in adult dogs. Most relapses in adult dogs respond to NSAIDs or corticosteroids.

Permanent limb deformities are rare. However, if they occur, surgery may help. Your veterinarian will use radiographs to determine if surgery is indicated.

Prevention

While it’s difficult to prevent a disease when you don’t know what causes it, some common sense can boost the chances that a puppy won’t get it. Large- or giant-breed puppies should not be given any mineral or vitamin supplements that aim to increase their growth rate and adult size. Slow and consistent growth is ideal for the puppy’s health because rapid growth can cause skeletal abnormalities. Puppies need a completely balanced diet. Puppies should be discouraged from doing jumping exercises until their growth plates have closed, which is at about a year of age. (Check with your veterinarian for an appropriate estimate of growth plate closure based on your puppy’s breed and growth.) Avoid housing puppies on hard surfaces, such as concrete. If floors are not carpeted, rugs may help so the puppies don’t slip as much.  

Prognosis

Most cases of HOD are resolved with or without medical care. Unfortunately, sometimes HOD is so severe, painful, and uncontrolled by treatment that owners are forced to discuss the pet’s quality of life issues, resulting in euthanasia.

What is Hepatitis?

Infectious Canine Hepatitis

One disease that causes chronic hepatitis is infectious canine hepatitis (ICH). ICH is caused by a virus but not the same as the Hepatitis A, B or C viruses that cause disease in humans; you and your family won’t get sick if your dog is infected. Similarly, The hepatitis viruses that cause human hepatitis do not affect dogs. ICH is spread through animal feces, urine, saliva and objects. Since most dogs are vaccinated as puppies against ICH, it is considered a rare infection. If you have a young puppy or an unvaccinated dog in your household, they can get ill with this virus. However, outbreaks sometimes occur, mostly in dogs less than 1-year-old or unvaccinated dogs. An infected dog may show signs of depression, fever, vomiting, diarrhea, and abdominal pain. Treatment involves supportive care such as fluids and medications to boost liver function; the latter may include SAMe, milk thistle, ursodiol, and vitamin E.

Causes 

Aside from ICH, there are many other causes of hepatitis. Causes of acute hepatitis include toxins, drugs, viruses, bacteria (particularly leptospirosis), and fungi. On the other hand, chronic hepatitis is caused by bacteria, viruses, excess copper in the liver, drugs, and immune system issues. If a cause cannot be determined, this is referred to as idiopathic hepatitis and is the most common cause. Idiopathic means no cause can be found.

Age and Breed Predispositions

Any dog can have an acute episode of hepatitis. Chronic hepatitis, on the other hand, is most common in middle-aged to older dogs; most dogs diagnosed with chronic hepatitis are 4-10 years old.

Some breeds are suspected to have a genetic predisposition to CH, making them more likely to develop it. These include the Bedlington Terrier, Doberman pinscher, West Highland white terrier, Dalmatian, English springer spaniel, American and English cocker spaniels, Jack Russell terrier, and standard poodle, Great Dane, Labrador retriever, and others. CH is also more common in females than males.

Signs

Dogs with acute hepatitis often have more severe signs than those with CH. Symptoms may include anorexia (lack of appetite), vomiting, diarrhea, dehydration, depression, fever, and jaundice (yellow discoloration of the eyes, gums, and skin), enlarged abdomen and weight loss. How serious your dog’s symptoms depend on how much liver damage they have and this may vary from mild to severe. In severe cases, there are signs of bleeding and bruising. Bleeding can occur inside the body or through any opening of the body, such as the nose and mouth.

Dogs with chronic hepatitis often appear normal early on. It is often surprising how normal the dog appears, even with significant progressing disease. This is why it is a good idea to pay attention to elevations in the liver enzymes (particularly ALT), as there is a better chance of slowing down the disease the sooner it is detected and appropriate management begins. As the disease gets worse, common signs are poor appetite, vomiting, diarrhea, depression, increased thirst and urination, weakness, jaundice, and weight loss. A small number of dogs have severe signs such as bleeding, incoordination, and behavior changes. Similar to acute hepatitis, bleeding can occur through any opening in the body.

Diagnosis

Similar to many illnesses, a thorough history and physical examination from your veterinarian are crucial to making a diagnosis. Drug history and potential exposure to toxins are particularly important as these can cause significant liver damage. Some dogs with hepatitis have increased levels of liver enzymes that can be seen on lab work. These increases do not have to be large to be important; they may indicate liver damage but can also be caused by many different diseases.

Elevated liver values are a common abnormality, but they are often non-specific and can be confusing to pet owners. Not all cases of elevated liver enzymes indicate specific liver disease. The liver performs many functions and, in some cases, the liver enzymes may elevate due to problems elsewhere in the body, or simply due to age. It is a good idea to look into these sooner rather than later, especially if your dog is one of the breeds predisposed to hepatitis. They may be the only abnormality a dog with chronic hepatitis has at that time.

To add to the confusion, some dogs with hepatitis can have normal liver enzymes. This normalcy does not rule out chronic hepatitis: CH can be so severe in some dogs that there is little functioning liver tissue left to release enzymes, making test results look ‘normal.’ If hepatitis is suspected, your veterinarian may recommend a serum bile acids test specifically to evaluate liver function. Another diagnostic test is an abdominal ultrasound. Abnormalities on these tests may strongly suggest hepatitis, but often do not pinpoint a cause. A liver biopsy is the most accurate way to make a diagnosis.

Treatment

Treating a dog with acute hepatitis involves supportive therapy such as fluids, medications and antioxidants.

Treating chronic hepatitis has several goals: treat the underlying cause, reduce inflammation and scarring/cirrhosis, provide supportive care, and treat complications. This support may involve changing current medications, use of antibiotics, and medication meant to reduce excess copper. Steroids, and/or other immunosuppressive drugs, may be used to reduce inflammation if infection is not suspected. Supportive care works to boost liver function, while treating complications depends on the specific problems.

Your dog may benefit from specific dietary changes depending on their individual condition and the cause of their chronic hepatitis. Dogs whose chronic hepatitis is associated with excess copper in the liver should be fed diets reduced in copper. They can also have a zinc gluconate supplement added to their food which acts to reduce copper levels as well. Regardless of cause, dogs with chronic hepatitis may benefit from diets with restricted protein levels. Restricted protein diets are not always necessary however and are only considered if your dog has evidence of protein intolerance. Your veterinarian will work with you to determine if your dog needs to be on a protein restricted diet. Another important dietary factor to consider for a dog with CH is how tasty and nutritious the food is. Dogs with CH often do not want to or are reluctant to eat. It’s important your pet’s food is appetizing to them and has high levels of carbohydrates and moderate levels of fat to provide them with their necessary calories. There is evidence that fiber may benefit dogs with liver disease and is another factor to consider increasing in your dog’s diet.

Prognosis

Your pet’s prognosis depends on the underlying cause of their hepatitis. In general, acute hepatitis has a better prognosis than the chronic form. If the liver is not too damaged, most dogs recover. Some, however, progress to chronic hepatitis.

According to one study, the average survival time with chronic hepatitis was two to three years, although individual results depend on the condition and response to treatment. Identification of the liver disease (via biopsies) is the best way to ensure the proper treatment. The prognosis is much worse if scarring and/or cirrhosis is extensive or blood clotting test results are abnormal. To ensure the health of your pet, it is important to not only treat hepatitis as soon as it is diagnosed, but also to look into abnormal test results such as elevated liver enzymes; these may be early signs of liver issues.

Many products may be helpful for dogs with weakness, especially rear leg weakness. These products may be available through your local pet supply store, various internet sources, or your regular veterinarian’s office. They may facilitate the lifestyle you and your dog enjoyed prior to arthritic limitations.

We can’t vouch for any of these products or their companies, but if something seems like it may be helpful for your pet, please research it further or contact the company directly and find out for yourself.

Shoes

Slippery floors are trouble for the weak dog. Many a dog can exhaust himself trying to rise on a hardwood or tile floor. Rubber shoes for dogs have been used to protect the paws of performance and rescue dogs. They also help with negotiating slippery floors. Since the introduction of boots, other products have been introduced to support mobility on slippery floors such as paw friction pads and toe covers that help grip.

Other items useful for slippery floors are rubber bathtub mats and yoga mats. These frequently provide the necessary friction for mobility.

Handles and Special Leashes

Raised Bowls

When the food and water bowls are located on the floor, it may be hard for a dog to lean down to reach them. Your dog may not be able to steadily bend his elbows and knees slightly so as to reach the food without becoming weak and having to lie down. And then it may be all the more difficult to stand up again.

Pet Ramp

Consider getting a ramp for your dog to get in and out of vehicles. This may be more comfortable for you and your dog than trying to lift them in or out when they are no longer able to jump. If your dog spends time with you on the bed or couch, the ramp may be helpful for them as well.

Their presence in the host intestine can cause diarrhea, though some hosts are symptom-free carriers. Different types of Giardia infect different types of animals; it is rare for Giardia from a pet to transmit to a human; furthermore, dog and cat Giardia species are separate and are unlikely to cross from dog to cat or vice versa.

Giardia have two forms: the trophozoite and the cyst. The trophozoite is the form that lives within the host, swimming around and attaching with its suction cup. The cyst, however, is the form that lives out in the environment. Trophozoites round up to cysts as they approach the colon and then are passed in feces. Trophozoites that don’t round up into cysts and form a shell prior to passing into the cold, cruel world cannot withstand the temperature/moisture variability of the outside world. Cysts are the contagious stage. Trophozoites are in the parasitic stage.

Life as a Giardia Organism

As mentioned, trophozoites and cysts may be passed in fresh feces, but only the hard-shelled little cysts can withstand the conditions of the outside world. The cysts live in the environment (outside the host’s body) potentially for months until they are consumed by a host. Inside the host, the cyst’s shell is digested away, releasing two trophozoites into the intestine, and the cycle begins again. Contaminated water is the classical source of a Giardia infection.

When a fecal sample is analyzed, the appearance of the Giardia organism depends on whether the sample is freshly obtained or if it has been outside of the host’s body for a while. Giardia organisms begin to round up into cysts in a matter of hours. The active trophozoites rather look like funny faces with the two nuclei forming the eyes and median bodies forming the mouth. Cysts look a bit more generic.

In the environment, cysts survive in water and soil as long as it is relatively cool and wet. A host animal will accidentally swallow a cyst when drinking from a puddle, or toilet, or when licking fur. After the cyst has been swallowed, the cyst’s shell is digested away, freeing the two trophozoites that go forth and attach to the intestinal lining.

As mentioned, the trophozoite will swim to a spot using its flagella and attach with its suction cup (more correctly called its “ventral disc”). Trophozoites tend to live in different intestinal areas in different host species but will move to other areas depending on the diet the host is eating. The trophozoite may round itself up and form a cyst while still inside the host’s body. If the host has diarrhea, both trophozoites and cysts may be shed in diarrhea; either form can be found in fresh stool.

After infection, it takes 5 to 12 days in dogs or 5 to 16 days in cats for Giardia to be found in the host’s stool. Diarrhea can precede the shedding of the Giardia. Infection is more common in kennel situations where animals are housed in groups.

How Does Giardia Cause Diarrhea?

No one is completely sure, but infection seems to cause problems with normal intestinal absorption of vitamins and other nutrients. Diarrhea is generally not bloody with a Giardia infection. Immune-suppressive medications, such as corticosteroids, can re-activate an old Giardia infection. We do not know why some infected hosts get diarrhea while others never do.

Diagnosis

In the past, diagnosis was difficult. The stool sample being examined needed to be fresh, plus Giardia rarely show up on the usual fecal testing methods used to detect other parasites. Several tricks have been developed to make Giardia easier to find (special stains, using special processing solutions, etc.), but what has made the biggest difference in the diagnosis of Giardia is the ELISA test kit, which is similar in format to a home pregnancy test. This method has dramatically improved the ability to detect Giardia infections and the test can be completed in just a few minutes while you wait.

Giardia shed organisms intermittently and may be difficult to detect. Sometimes pets must be retested in order to find an infection, and asymptomatic carrier animals are common. It should also be mentioned that the ELISA test can remain positive for some time after the infection has been eradicated so if re-testing is desired after a positive test, another test format may be more helpful than the ELISA test kit.

Treatment

Because cysts can stick to the fur of the infected patient and be a source for re-infection, the positive animal should receive a bath at least once in the course of treatment. 

At the least, the patient should have a bath at the end of treatment, plus it is especially important to promptly remove infected fecal matter to minimize environmental contamination.

Can Humans Be Infected?

The short answer is only rarely, so the concern is pretty low in general. However, maintain good hygiene practices such as regular hand-washing and removing fresh pet fecal matter promptly, as mentioned.

That said, here is a more detailed answer: Giardia duodenalis is classified into several subcategories called assemblages and designated A through G. Some assemblages are specific as to which host animals they can infect, and other assemblages are not so picky. Assemblage F, for example, only infects cats, and assemblages C and D only infect dogs but assemblage A will infect dogs, cats, people, rodents, wild mammals, and cattle. Common testing methods do not indicate what assemblage has been detected, so there is always a possibility of human transmission as long as the assemblage is unknown. 

Environmental Decontamination

Giardia cysts are killed in the environment by freezing temperatures and by direct sunlight. If neither of these is practical for the area to be disinfected, a chemical disinfectant will be needed. Organic matter such as dirt or stool is protective of the cyst, so on a concrete surface, do basic cleaning before disinfecting. Quaternary ammonia compounds can be used to kill Giardia cysts.

Animals should be thoroughly bathed before being reintroduced into a clean area. A properly chlorinated swimming pool should not be able to become contaminated. As for areas with lawns or plants, decontamination will not be possible without killing the plants and allowing the area to dry out in direct sunlight.

A Footnote on Vaccination

A vaccine against Giardia was previously available, not to prevent infection in a vaccinated pet but to reduce the shedding of cysts by the vaccinated patient. In other words, the vaccine was designed to reduce the contamination of a kennel where Giardia was expected to be a problem. This would be helpful during an outbreak in a shelter or rescue situation but is not particularly helpful to the average dog whose owner wants to simply prevent infection. Because of the limited usefulness of the vaccine, manufacturing was discontinued in 2009.

In Summary:

1. Giardia is a parasite that sticks to its host’s small intestine to feed.
2. It has two forms: one that lives in the environment (cyst) and one that lives in the host (trophozoite).
3. Cysts are the contagious stage. Trophozoites are in the parasitic stage.
4. Transmission is by the fecal-oral route from infected stool or contaminated water.
5. After infection, it takes 5 to 12 days in dogs or 5 to 16 days in cats to be found in the host’s stool.
6. Infection is more common in kennels or shelters where animals are housed in groups.
7. The parasite can cause diarrhea ranging from minor to severe.
8. We do not know why some infected hosts get diarrhea while others never do.
9. Giardia rarely transmits from a pet to a human or vice versa.
10. Diagnosis uses a fresh fecal sample. Several tests may be needed as false negatives can occur.
11. Treatment is dewormers and metronidazole (antibiotic).
12. A low-residue, highly digestible diet may be beneficial until stools are firm.
13. Because infective cysts can stick to fur, patients should receive a bath during and at the end of treatment.
14. The environment has to be cleaned after a case of giardiasis because it is so contagious. Giardia can be killed with common disinfectants. Quaternary ammonia compounds are the most effective.
15. Giardia cysts are killed in the environment by freezing temperatures and by direct sunlight.
16. To kill Giardia on a concrete surface, do basic cleaning before disinfecting.
17. Lawns and plants cannot be decontaminated without killing the plants and allowing them to dry out in direct sunlight.
18. No vaccine is available.

With the dog producing milk and sometimes mothering soft toys or pillows like Rosie in the illustration. So what should you do when this happens?

A Female Dog’s Normal Reproductive Cycle

Before talking about treatment, let’s explain the dog’s natural estrus cycle. The female dog comes into season approximately every 6 to 8 months, though this period becomes more erratic with age and is somewhat irregular when cycles first begin, and can come at longer intervals in certain breeds. 

When female dogs get older (say, seven or older), they do not stop cycling; there is nothing similar to menopause. Instead, as mentioned, cycles become irregular and long periods of time (years) can pass between cycles.

The second phase of the cycle is called estrus, which is characterized by the change in the character of the vaginal discharge from bloody to straw-colored. At this time, the female begins to allow the male to mount. It is classically the change from proestrus to estrus when ovulation occurs, and the female is most fertile. 

When the puppies are ready for birth, the corpus luteum is rapidly destroyed in a completely different hormonal sequence of events.

If she is not pregnant, the corpus luteum will simply wear out gradually and she will go back into the period of hormonal inactivity in which she spends the bulk of her time. This process of the corpus luteum wearing out in the absence of pregnancy takes at least 70 days, starting at the time of ovulation.  

Remember, during the 70+ days she has an active corpus luteum, her body essentially thinks she is pregnant and proceeds accordingly.

All the hormones are present; only the puppies are missing. If she is actually pregnant, the corpus luteum lasts through the 63 days of pregnancy. When the puppies are ready for birth, the corpus luteum is rapidly destroyed in a completely different hormonal sequence of events. Because the female dog is hormonally pregnant for 70 days after ovulation, one could say false pregnancy is a normal part of the cycle. We only treat it as a disease when it becomes extreme or fails to resolve naturally.

Clinical False Pregnancy

When false pregnancy persists, it can be a nuisance. The female dog can show the following signs:

• Nesting
• Mothering inanimate objects
• Lactating (giving milk)
• Abdominal distension
• She can even appear to go into labor.

Some female dogs are very sensitive to the hormonal fluctuations of their cycle. Diagnosis is made by history and physical examination rather than by blood test (though a blood test can be used to determine if she is actually pregnant or not). The key is to find symptoms of pregnancy in a female dog who is not pregnant. Symptoms generally become noticeable 6 to 12 weeks after estrus.

Treatment

If a more aggressive approach is needed, a diuretic such as furosemide can be prescribed. The idea is that mild dehydration will end the lactation.

Some people may want to try water deprivation, but this is potentially dangerous and should not be attempted without specific veterinary guidance.

If the above medication does not work, hormonal medications can be used. Progesterone can be used, but after the course of medication is complete, the false pregnancy recurs, so this is not a good choice. Estrogens are also not a good choice as they bring the dog back into estrus (vaginal discharge, attracting males, etc.). A week’s course of the male hormone mibolerone has generally been successful, but this medication is no longer available.

Hormones that inhibit prolactin (the hormone of milk production) are currently the best choices when medications are needed. Bromocriptine can be obtained from a compounding pharmacy and is given until lactation ceases (about a week or two). An upset stomach is not unusual with this medication. Cabergoline has fewer side effects and is given similarly but tends to be more expensive. Both these medications will cause abortion if the dog actually turns out to be pregnant, so it is important to be sure. A third medication called metergoline works a little differently to reduce prolactin but can also be used to end false pregnancy. Approximately 4-5 days of treatment are needed to stop the lactation and get things back to normal. Supplementing with vitamin B6 has been found to be helpful in regressing the false pregnancy as well.

A blood test can reliably detect canine pregnancy after 30 days from the breeding date. Ask your veterinarian about this test if you are not sure whether your dog is pregnant.

Spay during False Pregnancy?

It might seem like a good idea to spay the female to end the false pregnancy, as spaying will remove the ovaries and the corpora lutea they carry.

Unfortunately, this does not end the prolactin production from the pituitary gland so spaying may actually prolong the false pregnancy. Spaying during the diestrus period described above can actually trigger a false pregnancy. It is best to wait until the false pregnancy is over and then spay her to prevent future episodes. It is best to spay well after the 70-day diestrus period to avoid triggering a false pregnancy.

What is FCE, Anyway?

To understand FCE (fibrocartilaginous embolism), one has to understand some anatomy of the vertebral column. The vertebral column consists of numerous small bones called vertebrae that are linked together by joints called intervertebral disks. The disks are similar to the joints that connect arm or leg bones together in many ways. They allow flexibility between vertebrae so that you can arch or twist your back voluntarily, just as you can flex and extend a knee or elbow.

The disks are unique as well. A joint of the appendicular skeleton, say a knee or elbow, has a capsule that secretes a lubricating fluid. The bones are capped with smooth cartilage to facilitate frictionless gliding as the surfaces move during flexion and extension. The disk is nothing like this. It is more like a cushion between the end plates of the vertebrae. It is round (hence the name disk) and fibrous on the outside with a soft gelatinous inside to absorb the forces to which the bones are exposed. This jelly-like inside material inside is called the nucleus pulposus, and it is this material that makes up the fibrocartilaginous embolus.

The vertebral column provides a bony protective case around the vulnerable spinal cord.

The spinal cord is the cable of nerves and nerve connections that transmits messages to and from the brain and controls the reflexes of the body. The spinal cord is fed by a network of spinal arteries.   

In FCE, somehow the material from the nucleus pulposus, all the way in the center of the disk, gets into a spinal artery. The artery carries the nucleus pulposus material to the spinal cord until the artery becomes too narrow for the nucleus pulposus to go any further. The artery is plugged and the area of spinal cord it is supposed to feed dies. (The nucleus pulposis is “fibrocartilaginous” in nature, and the artery obstruction is an “embolism.”) This process is not painful except possibly briefly at first, but recovery is far from guaranteed.  The good news is that after the first 24 hours, the condition is not going to get worse. 

There are many theories of how disk material might gain access to the arterial blood supply, but no one really knows how this happens.

The Typical Patient

Any dog can be a victim of FCE,  although about half of the victims are large-breed dogs. Some feel the Miniature Schnauzer has a higher risk for FCE as this breed tends to circulate excess blood fats and cholesterol, which may predispose to embolism. 

Breeds that are called chondrodystrophic (meaning they have as part of their normal breed conformation dwarf-like characteristics) tend to calcify their disk material, making it too hard to participate in an FCE, and they are thus at lower risk. Such lower-risk breeds include Basset hounds and Dachshunds. Instead, these breeds tend to get Type I disk herniation, a different spinal problem but one at least amenable to surgery. 

Most FCE dogs are young adults between the ages of 3 and 6 years. In one study, 61% were evaluated after some kind exercise injury or trauma. There may be a yelp at the time of the trauma but the injury is generally not painful. There is about a 50:50 chance that the lumbar area of the spinal cord will be affected, which means only the rear legs will be involved. Because the embolism is not generally a symmetrical event, both left and right may not be equally affected.

Will My Dog Be Okay?

This depends on how much loss of function there is. The good news, as mentioned, is that the loss of function will not progress; after the first 24 hours, the maximum function loss has occurred. Your dog may or may not be able to improve (about 74% of dogs in one study showed some improvement ultimately; other studies show at least 50% of dogs can recover fully) but be prepared for no improvement and ask yourself what kind of care will be needed and can your dog get around. Maximum improvement has generally occurred by 3 weeks after the time of the injury, with some dogs showing some additional slow improvement over months.

Many dogs are completely paralyzed. See more information on caring for a paralyzed dog.

Many dogs are simply weak in the affected limbs. They may or may not need assistance in getting around. It all depends on how severe the embolism was and where in the spinal cord it occurred.

How Can We Be Sure This Was FCE?

Acute neurologic weakness after trauma could also be caused by Type I disk herniation or by spinal cord trauma. In Type I disk herniation, a mineralized intervertebral disk “slips” upward and presses on the spinal cord. The pressure may be relieved with medication (if it is not severe) or surgery may be needed. In either case, the spot where the disk is pressing is painful, and the pain is an important distinguishing feature. Beyond this, with disk disease, abnormalities may be seen when the patient’s back is radiographed, whereas in FCE, the radiographs will appear normal.

In some cases, the collapsed disk spaces are not obvious, and more advanced spinal cord imaging is needed. A myelogram involves general anesthesia and injecting dye in the space around the spinal cord. If there is an area of compression, it will be visible, and the patient can then proceed to surgery. In FCE, there is no such compression.

As for acute spinal cord trauma, it may not be apparent whether this or FCE has occurred. If the lesion is acute, it is not unreasonable to treat it as an acute spinal injury and see if improvement results.

Magnetic resonance imaging (MRI) is not yet readily available to most veterinary practices but is likely to become the imaging modality of choice for the diagnosis of FCE. MRI is able to distinguish embolized areas of the spinal cord from those with swelling or compression as long as at least 72 hours have elapsed from the initial event. Still, absolute confirmation of the FCE diagnosis requires a piece of spinal cord tissue for analysis, and this is not something that would be done in a living patient. For the time being, diagnosis of FCE is made based on the clinical picture of a patient in the appropriate age group with an acute spinal deficit, no other abnormalities on imaging, and no painful areas.

FCE is unlikely to be a recurrent condition, so that if a dog has one episode, they are not likely to experience another.

Physical Therapy

The resulting inflammation may target the GI tract or other organ systems, but in dogs and cats, the skin is frequently included in this immunologic activity.

Cats itch around the face or neck, which produces scabs and hair loss. In dogs, signs include facial itching, foot or limb chewing, itchy anal area, and recurrent ear infections.

Many people erroneously assume itching due to food allergy requires a recent diet change of some sort. In fact, the opposite is true.

Food allergies require time to develop; most animals have been eating the offending food for years with no trouble.

What Kind of Allergy?

Diagnosing and treating allergic skin disease and its secondary infections make up a large proportion of cases seen in small animal practice.  Pets can be allergic to insect bites (fleas are not inherently itchy unless the pet is allergic to flea bites), airborne proteins (such as molds, pollens, and dust mite parts), or foods. Pets can and often do have multiple allergies, adding together to make them itchy. The skin infections that come from scratching perpetuate the itching. To solve the problem, the infection must be cleared up and the offending allergen(s) removed from the pet’s world.

There is controversy about how common food allergy is in dogs and cats. Some experts feel it is relatively rare, while others feel is much more common than we realize. It is hard to tell because there is no simple test for food allergy, and the skin lesion distribution is difficult to distinguish from that of airborne allergy, which is frequently concurrent in the same patient.

So what are our clues that a pet has a food allergy? There are several hints:

• The itching is not seasonal (this is hard to tell in areas that do not freeze during winter).
• Itching started when the pet was less than six months of age or greater than five to six years of age.
• No response to treatment for sarcoptic mange (a condition with a similar itchy skin pattern).
• Corticosteroids have not helped manage the itching. Corticosteroids may or may not work on food allergy itching but they almost always work for other allergies.
• There are accompanying intestinal signs like vomiting or diarrhea. These are seen in 30 percent of food allergic pets.
• The lesion distribution is compatible with food allergy, especially if an itchy anal area and/or recurrent ear infections are involved.

Any of the above findings or observations warrant the pursuit of food allergy.

Please note that several of the above criteria relate to what you observe at home. Trouble results when the veterinarian must speak to different family members about the pet and there is disagreement in their observations. It is best to have one person, preferably the one who has the most contact with the pet, be the spokesperson and make the relevant judgments.

The Flea Factor

The short answer is not to waste money on these tests. Blood tests for allergy can detect antibodies against certain food proteins, but this does not necessarily mean the pet has an allergy. It may mean nothing more than the pet has eaten that type of protein before. Furthermore, the pet’s body may alter a food protein during digestion, and it is the altered protein that generates the allergy. There is no predicting how a protein could be altered and thus no test can be devised for altered proteins. Laboratory tests are simply not valid for determining if a pet has an allergy to a certain type of food.

Hypoallergenic Diet Trial

To determine whether or not a food allergy or intolerance is causing the skin problem, a hypoallergenic diet is fed for a set period. If the pet recovers, the original diet is fed for up to two weeks to see if itching resumes. (Actually, exposure to an allergen generally leads to itching within 12 hours, but it takes two weeks to be completely sure.)

If we see recovery with the test diet and itch with the original diet, then food allergy is diagnosed, and the pet is returned to either the test diet or another appropriate commercial food indefinitely.

There is no other way to determine if a pet has a food allergy. Blood tests are not useful.

Before reviewing diet strategies for this process, here are some additional concerns:

• The diet must be strict (meaning the pet should not have any other protein sources besides the test protein). This includes rawhides and chew toys, flavored chewable medications (these will need to be changed for unflavored tablets) and vitamins, and treats.
• All family members must be on board with the trial. No one should be giving the pet other foods or treats when no one else is looking.
• It is probably best for all animals in the house to be fed the test protein so as not to have food-sharing issues.
• Itching must be managed during the trial in a way that the results of the trial are not foiled.
• Diet trials often span a season change period. If a dog has a pollen allergy and winter comes during the period of the diet trial, it may appear that the diet worked when, in fact, the seasons simply changed. This is why a diet challenge is important at the end, even if the pet is doing well.
• The diet trial will take eight weeks. Most animals will respond in three to four weeks, but to be sure, you will need to feed the test diet for two months.

What Is a Good Hypoallergenic Diet?

There are two approaches to test diets: novel protein and hydrolyzed protein. Traditionally, a novel protein is used. This is a diet with a single protein source that the patient has never eaten before. It typically takes years to become allergic to a food protein so the patient should not be allergic to something new.

Fortunately, many pet food companies have discerned the need for diets using unusual protein and carbohydrate sources with a minimum of additives. Foods can be obtained based on venison and potato, fish and potato, egg and rice, duck and pea, and even kangaroo. Diets used for allergy trials must contain one protein and one carbohydrate source, and neither can be something the pet has had before. Recently, several diets that include duck, venison, and so on have been released to the general market. Be aware of foods that contain these ingredients because these ingredients will not be useable for future diet trials if they are ever used in the pet’s regular food.

It is important that no unnecessary medications are given during the diet trial. No edible chew toys (such as rawhides or bones) should be given. Treats must be based on the same food sources as the test diet. (Beware of rice cakes, though, as wheat is commonly used as a filler.) Chewable heartworm preventives should be replaced with tablets or topicals.

Over-the-Counter Food? Therapeutic Diet? Home Cooked?

Recently several pet food companies have released single protein diets for over-the-counter sales. These tend to cost less than the therapeutic diets available from your veterinarian’s office directly. While these diets are attractive, they are probably not a good choice for an actual diet trial. Immunological tests on these foods found that many of them contain additional proteins (probable contaminants from prior batches in the pet food factory). These impurities could defeat a diet trial which is hard enough to perform without such issues. The therapeutic diets did not have these contaminants.

Home cooking is a fine alternative to commercially prepared foods for the diet trial. The problem is that the test diets will most likely not be balanced but for the 2 months or so of testing, this should not be a problem. Home cooking is a bit of an inconvenience, but for the right person, it is a good choice. Ideally, a nutritionist should be involved in designing the diet. Recipes for appropriate diets can be purchased through BalanceIt, Petdiets.com or by any nutritionist listed at the American College of Veterinary Nutrition website.

The Hydrolyzed Protein Method

Several therapeutic diets are made from hydrolyzed proteins. This means that a conventional protein source is used but the protein is broken down into molecules too small to excite the immune system. There are various hydrolyzed diets on the market; discuss with your veterinarian which is best for your pet.

Trial Diet Timeframe

Studies have shown that 80 percent of dogs will have shown a response by 4 to 6 weeks on the diet, but by extending the diet to 8 weeks, 90 percent will respond. The Labrador retriever and cocker spaniel appear to require longer trials. Most veterinary dermatologists recommend 8 to 12 weeks, which is a long time to be strict on the diet, but that is the only way to detect food allergic dogs.

What To Do if the Diet Is Successful?

To confirm food allergy, return to the original food; itching generally resumes within 14 days if food allergy was truly the reason for the itchy skin. Many people do not want to take a chance of returning to itching if the patient is doing well; it is not unreasonable to simply stay with the test diet if the pet remains free of symptoms. Often it is difficult to remember 10 to 12 weeks later how itchy the dog used to be before the diet trial. The diet challenge helps make it more obvious whether the diet trial has worked or not.

It is possible to more specifically determine the identity of the offending foods after the pet is well. To do this, a pure protein source (such as cooked chicken, tofu, wheat flour, or any other single food) is added to the test diet with each feeding. If the pet begins to itch within two weeks, then that protein source represents one of the pet’s allergens. Return to the test diet until the itching stops, and try another pure protein source. If no itching results after two weeks of feeding a test protein, the pet is not allergic to this protein.

What To Do if the Diet Is Unsuccessful?

Assuming secondary skin infections have been controlled, an unsuccessful food trial is strongly suggestive that an inhalant allergy is a primary problem, but some other considerations should at least be mentioned:

1. Are you certain that the dog received no other food or substances orally during the trial?
2. Was sarcoptic mange ruled out?
3. Your pet may require a longer diet trial. Are you certain regarding the factor that pointed toward the food allergy?

If your pet has not been biopsied, now may be a good time. If an inhalant allergy has risen to the top of the list, symptomatic relief either via medication, baths with specific shampoos, or allergy shots will likely be necessary. Chronic itchiness can be extremely uncomfortable and prompt relief is our goal as well as yours.