Pathophysiology

Infection with Blastomyces occurs when a cat or dog inhales the fungal spores into the lungs. The incubation period is from 5 to 12 weeks. Some animals don’t show clinical signs for a long time after being infected, but those animals are not contagious to other animals and people. Blastomycosis organisms have a predilection for the respiratory tract, and pulmonary disease is the most common sign (88-94% of canine cases). Once the lung disease develops, yeast forms of the organism spread throughout the body. Organs typically affected include eyes, bones, skin, lymph nodes, subcutaneous tissues, brain, and testes. It can also be found in the nose, prostate, liver, mammary glands, and heart, but those locations are less common.

Dogs appear to be much more susceptible to infection than other species. Although the disease does occur in both people and cats, the incidence is much lower than in dogs. Dogs are ten times more likely to contract the disease than are people, and 100 times more likely than are cats. The incubation period in dogs is also shorter than in people. The reason dogs are more susceptible is unknown, but immune-deficiency may play a role. Annual prevalence in dogs in endemic areas is estimated at 1-2%. Many infected animals live within 0.25 mile of water. An increased number of cases can occur after periods of unusually heavy rainfall. Historically, young (i.e. 1-5 years), male, large-breed (e.g. hounds, pointers) dogs have had the highest risk of infection. (This is probably because these animals would tend to have more contact, due to hunting activities, with the organism’s geographical area.) However, any age, breed, or sex of dog can be infected.

Clinical Signs

The signs of illness will depend on what organs are infected. Some dogs will have eye problems, and some will have neurological signs (seizures, head tilt, etc.). Lameness may occur, if the infection is in the bones. Owners of dogs in the specific geographic areas should watch for coughing, difficulty breathing, eye inflammation, enlarged testicles, fever, swollen lymph nodes, ulcerated/draining skin lesions, bloody urine, difficulty urinating, nasal cavity signs (including bloody nasal discharge), and lack of appetite. (Weight loss occurs because of the decreased appetite.) Infections in the nasal passages may result in skull damage, and lead to infection of the brain. Large skin abscesses and neurologic signs are more common in cats than in dogs, while bone lesions are more common in dogs than in cats. Hypercalcemia can occur in dogs, although it’s rare in cats and non-domestic feline species.

Diagnosis

Diagnosis involves physical exam, blood tests, imaging (radiography, ultrasonography, CT, etc.), urinalysis to look for Blastomyces yeast, cultures, serology, and biopsies of affected organs. Fungal serology, to look for antibodies, is not always accurate and has been known to produce false negatives. The enzyme immunoassay (EIA) for B. dermatitidis galactomannan antigen appears to have a high sensitivity in urine (93.5%) and serum (87%). The EIA assay is commercially available; cross reactions with Histoplasma capsulatum, Coccidioides immitis, and Penicillium marneffei can occur with this assay. The definitive diagnosis is finding the fungus in the tissues.

Treatment

Treatment involves various antifungal medications, including itraconazole, ketoconazole, fluconazole, amphotericin B, and some combination therapies. These medications usually need to be taken for a long period of time; how long depends on the specific case. Treatment usually can be done at home, unless the disease is severe. Pets with respiratory involvement should be on restricted activity. In severely ill dogs, intravenous fluids, oxygen, antibiotics for secondary infections, and pain medication may be necessary. Skin lesions may require wound cleaning and debridement.

Eyes that are severely affected may not respond well to the treatment because the medication does not penetrate eyes very well. Ocular blastomycosis cases may need systemic and topical corticosteroid therapy, topical anti-glaucoma medications, etc. Significantly affected eyes may require enucleation (removal of the eyeball).

Pets with severe lung disease may get worse at the beginning of treatment because the fungal organisms are dying; the mass death of organisms can cause severe respiratory problems.

Patients may not appear to improve for one to two weeks after the start of treatment. Close monitoring should be done for the first two weeks, and then rechecks are usually scheduled on a monthly basis. Rechecks may involve blood tests, biochemistry profiles, and imaging, if appropriate.

Prognosis

The prognosis for many pets is good, especially if owners can afford to treat the pet for long enough. Approximately 50% to 75% of affected dogs recover when treated with itraconazole, fluconazole, or an amphotericin-ketoconazole combination. Prognosis is poor for dogs with severely affected lungs, but if the dog survives the first 7 to 10 days of therapy, the prognosis improves. However, mortality rates in dogs with Blastomyces dermatitidis can be as high as 41%.

The prognosis for the retention of vision, in animals that have eye disease, is variable.

Dogs with brain involvement often die. Seizures are common upon death of the organism and may be uncontrollable.

Prognosis is also poor when at least 3 body systems are involved.

Relapses are most likely to occur in dogs that had a severe case at onset, or dogs that were not treated long enough. Relapses are most common within the first 6 months after treatment. Dogs that recover from the disease are probably not immune to getting it again.

After discontinuing therapy, animals may be rechecked at 1, 3, and 6 months for evidence of relapse. In one study, relapse rates for itraconazole and fluconazole were 18% and 22%, respectively. Relapses are treated like a new infection.

There is no way to prevent your pets’ exposure to Blastomyces other than by keeping them away from affected geographic areas.

Zoonotic Potential

Blastomycosis is not considered to be a zoonotic disease. It is acquired by humans via inhalation or direct contact with infective conidia/spores. Risk of infection is higher for excavation workers, and for people working or playing in wooded areas with waterways. Blastomycosis cannot be spread between dogs and other animals, or between dogs and people. However, immunocompromised people should limit their contact with infected pets and should wear gloves when cleaning and treating draining lesions.

Definition and Causes

Chronic bronchitis is usually a non-infectious, inflammatory condition affecting the lining (mucosa) of the large airways (the trachea and bronchi) that results in a cough on most days for more than two months. In most cases, the specific cause of chronic bronchitis in dogs is not identified.  Chronic bronchitis is neither infectious nor contagious to other dogs; dogs will not pass it on to other dogs as they can in the acute form (see below).

Acute bronchitis, on the other hand, is most often caused by infectious agents, such as viruses (e.g. parainfluenza virus, adenovirus, canine influenza virus, distemper virus, or bacterial agents Bordetella bronchiseptica is the most common).  It is commonly termed kennel cough or canine infectious tracheobronchitis. Inflammation can also be caused by noxious irritants such as second hand smoke, foreign bodies, allergens (similar to hay fever in humans), foods allergens, and either migrating or primary lung parasites. In many of these cases, this acute bronchitis, occurring at the time of the infection or insult, will resolve with appropriate therapy from your veterinarian.  However, if the bronchitis persists long enough – generally, more than a few months – it is labeled chronic, and the cough itself can begin to cause and perpetuate airway inflammation.

Clinical Signs

Diagnosis

Chronic bronchitis is a diagnosis of exclusion.  Other diseases can cause clinical signs similar to chronic bronchitis.  These include tracheal collapse, laryngeal paralysis, lung diseases, lung cancer, heart failure, heartworm disease and infectious causes of acute bronchitis (listed above).  Your veterinarian will likely attempt to rule out many of these causes with a history, physical examination, and additional testing.

Diagnostic tests that are used to establish a diagnosis of chronic bronchitis include chest x-rays (thoracic radiographs), airway endoscopy (passing a small camera into the larynx, trachea and bronchi), collecting samples from the lower airways for culture and analysis of the cells in the airways (broncho-alveolar lavage or a transtracheal washing), and sometimes even echocardiography (examining the heart using ultrasound).  A fecal analysis might be needed to rule out parasites.

Treatment

Once a diagnosis of chronic bronchitis is made, your veterinarian will generally treat this condition with a variety of medications.

There are several things to remember about treating chronic bronchitis:

• The cough in chronic bronchitis is unlikely to completely disappear.  The aim is to reduce the coughing by more than 70-80%, and to reduce the severity of the coughing fits.
• Coughing begets coughing – the more a dog coughs, the more they irritate their airways, which stimulates more coughing.  Therefore, the aim is to initially break the coughing cycle.

Treatment of chronic bronchitis generally relies on using a combination of medications:

• Corticosteroids. These drugs are the main therapy for chronic bronchitis. They reduce and suppress the inflammation in the airways.  They can be given orally (pills) or with an inhaler.  Specific canine inhalers are required to properly administer steroids.
  
• Certain antibiotics, such as doxycycline, minocycline, or azithromycin may be given to rule out common infectious agents of the airways.  These particular antibiotics also have an anti-inflammatory effect, and may decrease coughing even if there aren’t any infectious agents.
  
• Cough suppressants.  These are usually narcotic-based preparations that require a prescription. They sometimes need to be given to the point of sedating the dog, especially early in treatment.
  
• Bronchodilators.  These may help by relaxing the airways, allowing air to move more easily into and out of the lungs. They can be given orally, by nebulizer, or by inhalers.

Your veterinarian might prescribe a combination of these drugs, and alter the doses as the disease is controlled to minimize side effects while still maintaining good control of the coughing.

An important factor in successful therapy of chronic bronchitis is weight loss.  If your pet is overweight, a loss of even 5-10% of the body weight can dramatically improve the coughing.  When the dog is overweight, improving your dog’s condition is completely in your hands; therefore, your veterinarian might prescribe a weight-loss program for your pet in addition to the medications.

Your veterinarian might also ask you to keep a “coughing log” to keep track of the severity and frequency of coughing, as this can help determine how successful the treatment is.

Prognosis

The prognosis for treating chronic bronchitis is good.  However, because this condition generally occurs in older dogs, other causes of chronic coughing (listed above) might complicate the management.  If coughing persists or recurs despite appropriate therapy, your veterinarian might be required to pursue other causes, or refer you to a specialist for additional diagnostic tests.

Dogs and cats can get more than just drunk when they drink ethanol, isopropanol, or methanol — they can get a trip to the emergency room. Pets can die from ingesting alcohol. 

What are ethanol, isopropanol, and methanol?

Isopropanol (isopropyl alcohol) is in rubbing alcohol (70%), some anti-freezes, some detergents, glass/window cleaners, perfumes/colognes, and alcohol-based topical sprays, including some pet flea-control and grooming products. Isopropyl alcohol is more than twice as potent as ethanol or methanol.

Methanol (methyl alcohol, wood alcohol) is most commonly found in automotive windshield washer fluids (20-80%) but is also in some gasoline additives, “canned heat” fuels (e.g., Sterno®), and some household solvents (e.g., paint removers).

Although the strength of these three alcohols varies, the clinical signs associated with their ingestion by dogs and cats are quite similar.

All poisoning problems boil down to the amount of alcohol ingested compared to weight, just like a dosage of medicine. Thus, when pets drink an alcoholic beverage that was left within reach or that was given to them intentionally by someone, it can cause a significant toxicity problem. In addition, significant absorption can occur through the skin or by inhalation.

Dogs are highly susceptible to the effects of alcohol. Signs of mild inebriation may occur with even minor exposure. Within 15 to 30 minutes after the pet has drunk the alcohol on an empty stomach (or within 1 to 2 hours on a full stomach), central nervous system (CNS) signs, such as staggering, excitement, or decreased reflexes, can begin. Behavioral changes can be seen, as can an increased need to urinate. As the problem gets worse, the pet may become depressed, have a slow respiratory rate, or go into cardiac arrest. Puppies and kittens are at particular risk because of their small size and immature organ systems. 

Alcohols are depressants, so many of the clinical signs associated with them are due to their effect on the CNS. Alcohols irritate the gastrointestinal tract. They also act as diuretics, and the alcohol and its metabolites are eliminated by the kidneys. Liver damage may occur after exposure, although it is much more common in animals that have repeated or chronic exposure. 

Clinical Signs

Clinical signs of intoxication can occur within 15-30 minutes of ingestion of alcohol. Signs include nausea, vomiting, thirst, urination, dehydration, lethargy, incoordination, disorientation, becoming cold (hypothermia), low blood pressure, and alcoholic bad breath. In severe cases, blindness, tremors, tetraplegia, respiratory depression, coma, or seizures may develop. Death is uncommon but may occur, especially if the pet has severe respiratory and cardiovascular depression, low blood pressure, and/or hypoglycemia. 

Diagnosis

Diagnosis is based on a history of exposure, combined with appropriate clinical signs and laboratory tests.  

Treatment/Management/Prevention

The treatments your veterinarian may use can include assisted ventilation, intravenous fluids (to improve elimination of the alcohol/metabolites, to provide cardiovascular support, and to correct electrolyte abnormalities), seizure control, and other supportive therapies. In addition, if the alcohol toxicosis is due to the ingestion of bread dough, your veterinarian may need to wash out your pet’s stomach with cold water to inhibit further alcohol production and to break up the dough mass for removal. In addition, your pet will be confined to prevent accidental self-injury.

Prognosis

Most dogs with alcohol intoxication can recover with adequate symptomatic and supportive care. Recovery may take 8-12 hours and tends to take longer if it was a severe intoxication or if isopropanol was involved.

Preventing Alcohol Toxicosis

All alcoholic beverages and alcohol-containing fluids should be kept out of reach of your dogs and cats. Consult your veterinarian before giving any ethanol-containing liquid medications.

Do not feed raw bread dough to your pets or leave bread dough out to rise in areas that can be reached by them. Always dispose of discarded bread dough carefully. 

The ASPCA National Animal Poison Control is available 24 hours a day at 888-426-4435. Expect an initial consultation fee of around $100.00 and additional follow-up is at no charge. You will be assigned a case number your veterinarian can use to communicate with a toxicology specialist before beginning treatment.