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fungus among us, part 4: cryptococcosis

  • Dr. Kim
  • Posted by Dr. Kim Smyth on
    Staff Veterinarian and Pet Health Writer of Petplan

Today, we conclude our week-long focus on fungal infections in pets. Of the blogs in this series focused on fungal infections, two focused on infections to which cats seem to be more resistant than dogs: blastomycosis and coccidiodomycosis. The third, histoplasmosis, affects cats just as easily as dogs. Today’s blog focuses on  the most common systemic fungal infection in cats (and which also affects cats more frequently than dogs): cryptococcosis.


Cryptococcosis, otherwise known as Cryptococcus neoformans, can infect indoor cats just as easily as outdoor cats, because the causative organism is carried indoors on shoes, on the wind or in soil used for indoor plants. Originally, the source of disease was thought to be pigeon feces, but more recently the culprit has been revealed to be vegetation, such as decomposing leaves and the grounds under tree habitats.


Because the fungus is inhaled, infection of the nasal cavity is common, and patients may be asymptomatic or enter a carrier state of disease. For other cases, colonization of the fungal organisms can occur and disease can then spread to the brain. Occasionally, other organs, such as the skin and internal organs are affected.  The incubation of cryptococcosis is still unknown, but it can range from one month to as long as 10 months.


Though cats are more commonly infected, young active dogs can also get the disease. Clinical signs in both include:

  • Blindness
  • Seizures
  • Uncoordinated gait
  • Nasal discharge
  • Low grade and/or intermittent fever
  • Inappetence
  • Lethargy
  • Skin lesions


Diagnosis can be made by finding the organism on microscopic examination, growing it in culture or finding it on a blood test.


Much like the other fungal disease that we’ve discussed, treatment will need to be continued over a long period of time - so again the benefits of having pet insurance coverage that covers chronic conditions can be very helpful. In the case of cryptococcosis, treatment with more than one kind of anti-fungal is often needed, and treatment may continue for one to two years. Luckily, clinical signs wane in the first month of treatment, so your four-legged friend will likely be much more comfortable early on in the treatment phase. The good news is that prognosis is excellent if patients survive the first two weeks of treatment.


As you can tell from this week’s blogs, systemic fungal infections can be very dangerous and detrimental to your pets. Though they are all slightly different, all four diseases can be life-threatening, and all four require serious time and financial commitments to treat.

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