06/24/2025
From the INDIANA STATE BOARD OF ANIMAL HEALTH
24 JUNE 2025
Expanding the Differential for Sick Cats
Determining the cause of illness in a domestic cat with outdoor exposure can be challenging.
The prevalence of the H5N1 highly pathogenic avian influenza (HPAI) throughout Indiana made that virus a logical addition to the differential diagnosis list for sick cats. This summer, practitioners in southern Indiana began to report cats which presented with lethargy, fever, poor appetite and eventually death. HPAI was a significant concern but didn’t fit epidemiologically. Laboratory tests confirmed these cats were infected with cytauxzoonosis.
Cytauxzoonosis is also known as “Bobcat Fever” since bobcats are a natural host of the parasite which causes illness (Cytauxzoon felis). Most infected bobcats show no clinical signs of illness but can become persistent carriers of the disease. The infection is typically spread to domestic cats through the bite of the lone star tick (Amblyomma americanum) but can also be caused by the bite of the American dog tick (Dermacentor variabilis). Cats cannot catch the infection directly from an infected cat or through the ingestion of a tick.
Clinical signs usually develop 5 days to 14 days after the tick bite (average 10 days) and may include lethargy, inappetence, fever, difficulty breathing, anemia, jaundice and seizures. Affected cats may also have enlarged lymph nodes, spleen and / or liver. Death may result within 2 days to 3 days after the detection of fever without medical intervention.
Testing
Blood samples may be submitted to the Indiana Animal Disease Diagnostic Laboratory (ADDL) for testing. In recent weeks, ADDL has confirmed cases in Greene, Martin and Monroe counties.
Prevention and Treatment
Owners of cats that spend time outdoors should be advised to use a flea and tick preventative to prevent cytauxzoonosis. Because the disease can be fatal in just a couple of days, clinics in high-risk areas may choose to stock treatment medication to allow rapid treatment of cases.
The disease is not known to affect dogs or other non-feline species.
The Indiana Department of Health’s medical entomologists maintain an online dashboard to track tick activity statewide to help citizens stay informed about the risk of exposure to tick-borne illness
KEEP YOUR CATS ON FLEA AND TICK PREVENTION ALL YEAR ROUND!!