Cytauxzoonosis is a deadly danger to cats. The microscopic protozoal parasite, Cytauxzoon felis, that causes the disease is transmitted via the bites of infected ticks. The disease is most commonly diagnosed in cats that live in the South Central and Southeastern United States and go outdoors. Even when receiving the most effective treatment available, approximately 40% of cats diagnosed with cytauxzoonosis still die. Owners in high risk areas must understand the risks associated with this disease and what can be done to prevent it.
How Cytauxzoonosis Develops
Bobcats are thought to be the reservoir host for cytauxzoonosis. As many as 50% of bobcats in a particular area may be infected, but they rarely develop severe disease as a result. Ticks will bite an infected bobcat (or any other type of felid that has Cytauxzoon felis in its bloodstream) and then transmit the microorganism to cats that it attaches to in the future. People and non-feline animals cannot develop cytauxzoonosis either via tick bites or through contact with a sick cat. In fact, direct cat-to-cat transmission is also impossible; it appears that ticks are a necessary part of the microorganism’s life cycle.
Cytauxzoon felis initially infects tissues throughout the body and then red blood cells. The result is a massive stimulation of the immune system and destruction of red blood cells leading to anemia. Sick cats typically develop some or all of the following symptoms:
- loss of appetite
- abnormally pale or yellow mucous membranes
- increased respiratory rate and effort
- enlarged lymph nodes, spleen, and liver
Cats can also become chronic carriers of cytauxzoonosis; they harbor small numbers of the protozoa in their bloodstream but aren’t overtly ill themselves. These individuals serve as a reservoir for the disease, potentially infecting other cats via ticks. Veterinarians can diagnose most cases of cytauxzoonosis with a blood smear and/or a laboratory blood test.
Treatment and Prevention
Without treatment, almost every domestic cat that develops significant symptoms of cytauxzoonosis will die within a week or so of becoming ill. Treatment with a combination of atovaquone, an anti-malarial drug, and the antibiotic azithromycin can save up to 60% of cats, but atovaquone is expensive and not something that veterinary clinics typically have on their pharmacy shelves. The anti-protozoal drug imidocarb may also be used but can be expected to save only about a quarter of the cats that receive it. Infected cats also may require intravenous fluids, heparin therapy, and blood transfusions.
Because of the severity of cytauxzoonosis and the difficulty and expense of treating it, cat owners should focus on prevention. If you live in a high risk area, try to keep your cat indoors and use an effective tick control medication, like those that contain fipronil, every month.