Introduction

Histoplasmosis is a serious, systemic fungal disease which occurs in cats that ingest or inhale a soil-dwelling organism called Histoplasma capsulatum. This fungus is endemic in many areas, and not all cats that are exposed will develop clinical disease. The infection can be difficult to diagnose and can be fatal. Thankfully, once it is diagnosed, it is normally successfully - and permanently - treatable. The treatment is expensive, but the prognosis is good for cats without significant lung involvement and damage before treatment begins.

Treating Histoplasmosis in Cats

The goal of treatment is to completely clear the infection from the cat. The duration of treatment and the selection of appropriate anti-fungal drugs must be decided upon by a veterinarian, because the treatment protocols may differ in cases of disseminated versus mild disease. Speaking generally, anti-fungal azole medications are used to combat this infection. They normally need to be administered orally, twice a day, for at least 4 to 6 months depending upon the severity of the cat’s condition and its response to treatment. In severe cases where hospitalization is necessary, additional intravenous medications may be added to the protocol, together with oxygen, fluids and nutritional support. The azole drugs can cause gastrointestinal side effects (vomiting, diarrhea, lethargy and abdominal pain) and normally should be given with meals. Anti-fungal medications are expensive, but less so in cats than in dogs because of cats’ smaller size.

Affected cats should remain on a high-quality, palatable diet with free access to fresh water to ensure adequate nutritional support and hydration. Regular visits to the veterinarian for assessment of progress are important and may include repeated chest radiographs for cats with significant lung involvement.