As the weather warms and tick activity increases, there is one feline disease that veterinarians in Kansas and Missouri remain particularly concerned about: cytauxzoonosis. While many people have never heard of it, this disease can progress rapidly and become life-threatening in a matter of days. Early recognition and prompt veterinary care can make a significant difference in a cat’s chance of survival.

Cytauxzoonosis is caused by a microscopic blood parasite called Cytauxzoon felis. The parasite primarily circulates in wild felids, especially bobcats, which serve as the natural reservoir host, earning Cytauxzoonosis the nick name “bobcat fever”. Domestic cats become infected when they are bitten by an infected tick carrying the organism.

The lone star tick (Amblyomma americanum) is considered the primary vector responsible for transmission in our region, although the American dog tick (Dermacentor variabilis) has also been implicated. Because both of these tick species are common throughout Kansas and Missouri, cats in these states are at an increased risk for exposure.

Once an infected tick feeds on a cat, the parasite enters the bloodstream and begins multiplying within certain blood cells. As the infection progresses, these infected cells can obstruct blood vessels and trigger widespread inflammation throughout the body. Typically, this disease often advances very quickly.

Cats with cytauxzoonosis may initially show vague signs of illness, such as decreased appetite, lethargy, hiding behavior, or fever. Over the next several days, symptoms can worsen dramatically. Owners may notice difficulty breathing, pale or yellow gums, dehydration, weakness, vocalization, or collapse. Most affected cats become critically ill within a week of developing signs, and many are presented to veterinary hospitals as emergencies.

Diagnosis often involves a combination of physical examination findings, bloodwork, and microscopic evaluation of a blood smear. Cats with cytauxzoonosis commonly have abnormalities such as anemia, low platelet counts, elevated bilirubin levels, and evidence of inflammation or organ dysfunction. In some cases, the parasite can be identified directly within red blood cells or other blood cells under the microscope. Polymerase chain reaction (PCR) testing may also be used to confirm the diagnosis, particularly when blood smear findings are inconclusive.

Historically, cytauxzoonosis carried an extremely poor prognosis, with survival rates often reported at less than 10%. Fortunately, advances in treatment have improved outcomes significantly. The current recommended therapy generally includes a combination of atovaquone and azithromycin, along with aggressive supportive care. Hospitalization is often necessary, and many cats require intravenous fluids, nutritional support, medications to control nausea and fever, oxygen supplementation, blood transfusions, or other intensive treatments depending on the severity of their illness.

Even with appropriate treatment, cytauxzoonosis remains a very serious disease. Survival rates vary among studies, but approximately 40% to 60% of cats receiving prompt treatment may survive. Cats that do survive often require close monitoring throughout recovery, and some may remain persistently infected without showing outward signs of illness. Because of the rapid progression associated with this disease, delaying veterinary evaluation can significantly decrease the likelihood of a positive outcome.

Prevention remains the most effective strategy. Since transmission occurs through tick bites, consistent use of veterinarian-recommended tick prevention products is essential. Keeping cats indoors whenever possible can further reduce exposure risk. Even cats that spend only limited supervised time outside may encounter ticks in backyards, wooded areas, or regions with tall grasses.

Kansas and Missouri are considered endemic areas for cytauxzoonosis, meaning the disease occurs regularly within these states. While cases are diagnosed every year by veterinarians throughout the region, exact statewide case numbers are difficult to determine because cytauxzoonosis is not a routinely reportable disease in either Kansas or Missouri., but it is critical to act quickly if your cat is demonstrating symptoms as patients truly will pass in as little as a week.

If your cat develops sudden lethargy, loss of appetite, fever, or any other signs of illness—especially during tick season—prompt veterinary attention is critical. Cytauxzoonosis is one of the most serious tick-borne diseases affecting cats in our region, but early recognition, rapid intervention, and diligent prevention efforts offer the best chance for a favorable outcome. This illness is of particular importance to us at AcuteVet as we have diagnosed more than 5 cases within the past year. We make a point of keeping the medication in stock and are here to help if you have any concerns or questions.