Fungal Infection (Histoplasmosis) in Cats

By PetMD Editorial on Jan. 13, 2009

Histoplasmosis in Cats

Histoplasmosis refers to a fungal infection caused by the Histoplasma capsulatum fungus. It usually enters an animal's intestinal tract after being ingested through contaminated soil or bird droppings.


The most common symptoms for cats are lack of appetite, weight loss, and difficulty breathing. Other potential signs may include:

  • Coughing
  • Increased breathing effort and harsh lung sounds
  • Lameness
  • Eye discharge
  • Diarrhea
  • Fever, up to to 40 degrees Celsius (104.0 degrees Fahrenheit)
  • Pale gums and moist body tissues (mucous membrane)
  • Enlarged lymph nodes (lymphadenitis)


The primary cause of this infection is the ingestion of the Histoplasma capsulatum fungus. The fungus may be breathed in when contaminated soil is disturbed, such as when a cat scratches at dirt that it has used for its own waste, or when your cat comes into contact with contaminated bird (including poultry) or bat droppings.


Your veterinarian will want to differentiate the symptoms from heart failure, feline asthma, lymphoma, pyothorax, and fungal pneumonia. A chemical blood profile, complete blood count, and a urinalysis will be conducted. Blood tests may confirm the presence of histoplasma antibodies, although this only means that your cat has been exposed, not that it is in a diseased state. Further differential testing will either confirm or rule out the actual state of histoplasmosis.


Veterinarians will usually treat this condition with medications on an outpatient basis. If inpatient treatment is recommended, it may be because your cat has been unable to eat and is suffering from malabsorption. If this is the case, your veterinarian will administer drugs, fluids, and nutrients intravenously until your cat's condition has improved.

Living and Management

After treatment, your cat's activity level should be reduced until it is fully recovered. Cage rest, or restriction to an enclosed environment will allow your cat to fully recuperate. If the condition does recur, a second course of treatment may be needed.


To prevent the development of histoplasmosis, you will need to try to prevent your cat from being exposed to possible sources of contamination, such as where birds, poultry, or bats might roost, or around soil that is known to have bird droppings in it.

Image: Rommel Canlas via Shutterstock

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