Cytauxzoonosis is a severe, rapidly progressing tick-borne disease that affects domestic cats. It is caused by Cytauxzoon felis, a protozoan parasite transmitted through the bite of an infected tick. Without prompt emergency treatment, the disease is often fatal within three to seven days of the first symptoms appearing.
Oklahoma sits in the heart of the endemic zone for this disease. Cats across Tulsa, eastern Oklahoma, and the surrounding region are at real and ongoing risk, particularly during tick season from spring through fall.
Cytauxzoonosis is caused by the single-celled parasite Cytauxzoon felis. Bobcats are the natural reservoir host for this organism and typically carry it without becoming critically ill. Domestic cats are incidental hosts and have no natural tolerance for the parasite, which makes infection extremely dangerous for them.
The disease is sometimes called "bobcat fever" because of this connection. The name is informal, but the disease itself is very serious.
Cats contract cytauxzoonosis through the bite of an infected tick. The primary tick species responsible are the lone star tick (Amblyomma americanum) and the American dog tick (Dermacentor variabilis), both of which are widespread in Oklahoma.
Transmission requires a tick to be attached and feeding. The Centers for Disease Control and Prevention (CDC) notes that prompt tick removal reduces the risk of pathogen transmission, though with some tick-borne diseases the transmission window can be brief.
Cat-to-cat transmission does not occur. A cat cannot spread cytauxzoonosis to another cat or to people.
The most common signs of cytauxzoonosis include:
Symptoms often appear suddenly. A cat that seemed healthy the day before may be in critical condition within 24 to 48 hours. Fever and lethargy are typically the first warning signs owners notice.
Cytauxzoonosis progresses rapidly. Most cats deteriorate from early symptoms to severe illness within two to five days. The parasite causes obstruction of small blood vessels and widespread organ involvement, which drives this fast decline.
Time is the most critical factor in treatment outcomes. The American Veterinary Medical Association (AVMA) recognizes cytauxzoonosis as a veterinary emergency requiring immediate intervention. Waiting to see if a symptomatic cat improves on its own is not recommended.
Diagnosis typically involves a blood smear exam and PCR testing. Under a microscope, the parasite may be visible inside red blood cells as a distinctive "signet ring" formation. PCR testing confirms the presence of Cytauxzoon felis DNA and is the most sensitive diagnostic method.
Additional bloodwork will often show anemia, low white blood cell counts, low platelet counts, and elevated liver values. These findings help the emergency team assess severity and guide the treatment plan.
Treatment for cytauxzoonosis requires hospitalization and intensive supportive care. The current standard-of-care antiparasitic protocol combines atovaquone and azithromycin, a regimen shown in research to significantly improve survival rates compared to older treatment approaches.
Supportive care typically includes:
Treatment is complex and requires continuous monitoring by an experienced emergency team. The emergency team at Oklahoma Veterinary Specialists is available 24 hours a day, 7 days a week, 365 days a year to evaluate and manage cats with suspected cytauxzoonosis.
Historically, cytauxzoonosis carried a mortality rate of 60% to 90% in domestic cats. The introduction of atovaquone-based combination therapy has meaningfully changed those outcomes.
Published research has reported survival rates of 60% or higher in cats treated with the atovaquone and azithromycin protocol alongside aggressive supportive care. Early presentation remains one of the strongest factors associated with survival. Cats brought in at the first signs of illness have better outcomes than those who arrive in advanced stages of disease.
Indoor cats face a lower risk, but the risk is not zero. Ticks can enter homes on clothing, shoes, other pets, and through briefly opened doors. Any cat with potential tick exposure, even limited outdoor access, should be considered at risk.
The Cornell University College of Veterinary Medicine recommends discussing tick prevention options with a veterinarian for all cats, regardless of lifestyle. Year-round tick prevention is especially important for cats in Oklahoma given the geographic prevalence of the disease.
Prevention focuses on reducing or eliminating tick exposure. Recommended steps include:
Never apply a tick preventive to a cat without confirming it is safe for feline use. Many products containing permethrin are highly toxic to cats and should be kept away from them entirely.
Seek emergency veterinary care immediately if your cat develops any of the following after possible tick exposure:
Do not wait for a regular veterinary appointment if these signs appear. Cytauxzoonosis can be fatal within days, and early treatment is the most important factor in survival.
The emergency team at Oklahoma Veterinary Specialists in Tulsa is here whenever you need us. No appointment is necessary. If you are concerned your cat may have been exposed or is showing symptoms, come in or call us at 918-299-4900.
Oklahoma Veterinary Specialists delivers 24-hour emergency care and board-certified specialty services with advanced technology and compassionate treatment.
