Histoplasmosis In Cats Symptoms and Treatments

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Most animals affected by this fungus probably have in apparent or very mild clinical signs and recover without treatment. A few animals have major problems with this organism. This infection can occur almost anywhere but is more prevalent in humid moist areas and is most commonly a problem in the Mississippi and Ohio River areas. The infection primarily affects the lungs and gastrointestinal systems so clinical signs tend to be associated with these sites -- coughing, tiring easily, weight loss, lethargy and diarrhea. Many other signs are possible if the infection spreads to other organs. This is usually diagnosed by transtracheal wash samples from the lungs or biopsy of the intestines. It is usually treated with ketaconazole for a minimum of three months and sometimes longer.

Histoplasmosis is relatively uncommon but is reported more frequently in cats than in dogs. Histoplasmosis is supposed to more common in young cats than in older ones too. In many instances, these variations have been correlated with proximity to bird habitats, which are often heavily contaminated because bird droppings serve as a good medium for the organism. Birds are not infected by the Histoplasma organism, although they can carry the organism on their feathers and spread the disease in this manner. Bat habitats can also be heavily contaminated with the organism, as bat guano is an excellent medium for Histoplasma growth. Unlike birds, bats can become infected with the organism.

Infection occurs when spores in the air are inhaled. The spores go to the lungs and cause infection of cells deep in the lungs. Most cats show a clinically unapparent pulmonary infection; the organism has infected the lungs, yet the cat shows no signs of being ill.

The most common symptoms in the cat or dog are weight loss, fever, loss of appetite, and depression. Diagnosis can be tricky in cats because the prominent signs of fever, weight loss, depression, poor appetite and anemia suggest a generalized infectious or inflammatory process that is not specific for any organ in particular. Emaciation is a predominant and conspicuous feature. Cats may show labored or fast breathing, and this can be due to anemia, or due to lung disease. Labored breathing with increased lung sounds is present, and many animals may also have a cough. In addition to these symptoms, both cats and dogs may be anemic and have pale gums.

The treatment of choice is an oral antifungal drug. The most commonly used ones are itraconazole or fluconazole. Ketoconazole is sometimes used when cost is a consideration, though it may not be as effective and can be more toxic than itraconazole.

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