By Caroline O’Sullivan DVM, MS

Histoplasmosis (Histoplasma capsulatum) is a fungus. This fungus is found worldwide and is called the “OHIO River Valley fever” because it is endemic in the Ohio and Mississippi River Valley and Appalachian Mountains.

Don’t let me name fool you or your veterinarian. Living far away from the Ohio River Valley and the Mississippi allows us to disregard “HISTO” as a diagnosis is the West.

When we have unexplained coughing and non-specific medical signs here in the West, we think about the possibility of Valley Fever (coccidiodomycosis).Valley Fever is limited to the Southwest region of the United States as well as Mexico and Central and South America.

SO here in the West, we may consider Histoplasma as a “ZEBRA”. But not anymore. Histoplasmosis is everywhere, so let’s be aware.

What is a Respiratory Fungus?

Histoplasmosis and Coccidiodomycosis are both NON-Contagious infections. The infections are caused by fungal spores in the soil. The disease can come with the wind. Inhalation of the fungal spore is the most common form of infection.

The first clinical signs in your dog and cats may be respiratory, such as coughing, sneezing and nasal discharge. These signs may be self limiting and/or accepted as another condition such as allergies or sinus irritation.

If the fungus gets into the blood stream, it can go anywhere and cause a wide range of clinical signs that may not be thought of as fungal. If your dog or cat has a condition that does not resolve with traditional medical care, you may want to consider getting your pet tested for fungal infection.
It may not be the first ideas of the list (a ZEBRA), but it is important to know it exists and allow this information to make you a better animal advocate.

Chasing ZEBRAS – “When you hear hoof beats, think horses………but don’t let the ZEBRAS run you over” I believe this was taught to us in every single veterinary medical classroom.