Cats can be exposed to fungal infections by ingestion, inhalation, or absorption through their skin, and these pathogens frequently manifest as ocular disease. Our team at Veterinary Vision Center wants to provide information about problematic fungal infections for cats, in case your pet is affected.

What cat owners should know about cryptococcosis

Cryptococcosis, which is usually caused by Cryptococcus neoformans and Cryptococcus bacillisporus, is the most common systemic fungal disease in cats. Commonly found in droppings of birds, such as pigeons, the fungal spores are thought to be transmitted by inhalation. Indoor and outdoor cats are susceptible to the disease. 

  • Signs — Cryptococcus has four forms:
    • Nasal — The nasal form, which is most common, is characterized by sneezing, nasal discharge, and masses in the nasal cavity.
    • Nervous system — A cat’s central nervous system can be affected when the nasal form spreads and enters the brain from behind the nasal cavity. Signs include sudden blindness, seizures, and behavioral changes.
    • Cutaneous — Signs include non-painful, non-itchy nodules on or below the skin. Lymph node enlargement may also be seen.
    • Systemic — When the infection spreads through the bloodstream, eye involvement can include retinal detachment and inflammation in various parts of the eye. These cats usually also experience lethargy and inappetence.
  • Treatment — Treating cryptococcosis involves prolonged anti-fungal administration, and surgically removing lesions. The antifungal should be able to cross the blood-brain barrier, if the eye is affected.
  • Prognosis — Cats affected by the neurological form have a guarded prognosis, but other forms have a good to excellent prognosis, as long as the cat receives the appropriate treatment for the recommended time.
  • Prevention — Don’t allow your cat near bird droppings.

What cat owners need to know about histoplasmosis

Histoplasmosis, which is caused by Histoplasma capsulatum, is the second-most common systemic fungal disease in cats. Transmission occurs when a cat inhales or ingests infectious spores that are most commonly found in soil contaminated by bat and bird feces. While outdoor cats are at higher exposure risk, potted plants and unfinished basements are possible exposure routes for indoor cats.

  • Signs — Signs can be non-specific, including lethargy, weight loss, inappetence, and fever. Potential ocular signs include granulomatous chorioretinitis, conjunctivitis, retinal detachment, and secondary glaucoma.
  • Treatment —An appropriate antifungal should be given for six months, or two months after their signs resolve. Topical eye medications may also be needed to control inflammation.
  • Prognosis — Prognosis depends on the infection’s extent and severity. If cats have significant ocular involvement, their prognosis for vision return is guarded to poor.
  • Prevention — Don’t allow your cat to access areas such as chicken coops, bird and bat roosts, and construction and excavation sites.

What cat owners need to know about blastomycosis

Blastomycosis is caused by Blastomyces dermatitidis. The fungus lives in soil, and transmission usually occurs when cats inhale infectious spores, although they can also be inoculated through a skin wound. 

  • Signs — Signs include difficulty breathing, lethargy, weight loss, fever, and skin lesions. Possible ocular manifestations include severe uveitis, blindness, and chorioretinitis.
  • Treatment — Treatment involves prolonged antifungal administration. Ocular blastomycosis may require systemic and topical treatment for inflammation, and significantly affected eyes may require removal.
  • Prognosis — Prognosis for cats is good, as long as the appropriate treatment is provided for the necessary time period. Prognosis for vision retention depends on how extensively the cat’s eyes were affected.
  • Prevention — Don’t allow your cat access to areas such as wooded regions near waterways and excavation sites.

What cat owners should know about aspergillosis

Aspergillosis is caused by Aspergillus organisms, which are found in soil and decaying undergrowth. Infection is most commonly seen in cats who have a compromised immune system, such as those affected by feline leukemia virus, cancer, or diabetes. Outdoor and indoor cats are susceptible, and transmission occurs when they inhale an infectious spore, possibly through spore accumulation in food or litter. 

  • Signs — Two aspergillosis forms occur in cats:
    • Sino-nasal — Signs include sneezing, nasal discharge, epistaxis, and masses in the nose.
    • Sino-orbital — Signs include a bulging eye, third eyelid elevation, blindness, and balance difficulties.
  • Treatment — Treatment involves surgically removing affected tissue, and antifungal medications.
  • Prognosis — Prognosis depends on the infection’s extent and severity. Cats affected by sino-nasal aspergillosis have the best prognosis, but treatment failure is still common, and reinfection frequently recurs.
  • Prevention — Don’t allow your cat to access areas with decaying undergrowth.

What cat owners should know about coccidiomycosis

Coccidiomycosis, also known as Valley Fever, is caused by Coccidioides immitis, and is most commonly found in southwestern United States, Mexico, and Central and South America. Infection typically occurs when infectious spores are inhaled after dry soil has been disturbed, such as following a dust storm, earthquake, or construction.

  • Signs — Signs are non-specific and include fever, inappetence, and weight loss. Ocular manifestations include retinal detachment and uveitis.
  • Treatment — Prolonged antifungal treatment is necessary, and topical ocular treatments may also be needed to manage the inflammation.
  • Prognosis — Long-term prognosis is guarded, since relapse is common.
  • Prevention — Don’t allow your cat to access areas where dust has been disturbed.

Fungal infections can significantly damage your cat’s eyes, but if diagnosed quickly, treatment may save their vision. If your cat has a fungal infection that is affecting their eyes, contact our team at Veterinary Vision Center, so we can provide treatment to protect their vision.