Bobcat Fever (Cytauxzoonosis) in Cats

Bobcat fever in cats (aka Cytauxzoonosis) is a rare infectious disease that is often fatal for cats. It is spread by the bite of an infected tick. Most cases of bobcat fever in the United States are reported between March and September in southeastern and south-central states. It is also seen in mid-Atlantic states, upper midwest states, and the West Coast of the U.S. 

In this article, you will learn what bobcat fever is, what causes it, which cats are at higher risk for the disease, symptoms to watch for, how it is treated, and also tips for prevention.

What is Bobcat Fever?

Bobcat fever is an infectious disease seen in cats. It is spread when a cat is bitten by a tick that is infected with a microscopic blood parasite called Cytauxzoon felis or C. felis for short. The official medical term for bobcat fever is cytauxzoonosis. Bobcats are traditionally considered the main wildlife reservoir host of C. felis. However, other wildcats, including the Florida panther, are also considered to be reservoir hosts that perpetuate the disease in the wild.

Bobcat fever is rare in cats, but is seen in both domestic and feral cats of all ages and genders. Cats who roam outdoors in places where reservoir hosts live or live with a cat who is already infected with cytauxzoonosis are at increased risk for the disease. Bobcat fever poses no infectious risk to humans or dogs.

Causes of Bobcat Fever in Cats

Cytauxzoonosis in cats is caused by the bite of a tick that is infected with a microscopic blood parasite called C. felis. Ticks that carry C. felis include the lone star tick (Amblyomma americanum) and the American dog tick (Dermacentor variabilis). The parasite multiplies in the bloodstream of an infected cat and causes related symptoms. 

Typically, bobcat fever is not spread directly from cat to cat, as the parasite requires a tick to complete the full life cycle. However, bobcat fever can also be spread by bite wounds from an infected cat, a blood transfusion from an infected cat, or accidental inoculation by contaminated needles or surgical instruments, but this is rare. Cats infected by these routes typically only develop mild symptoms or no symptoms at all.

Bobcat Fever Symptoms in Cats

Bobcat fever symptoms are typically severe — these cats are usually very sick by the time they are seen by a veterinarian. You might think that seeing ticks on a cat is a common symptom of bobcat fever. Even though bobcat fever is spread by tick bites, it can take up to three weeks for symptoms to develop after the initial bite. Therefore, there may be no ticks present on a cat who is sick from bobcat fever.

Symptoms are associated with the destruction of red blood cells, inflammation of blood vessels, anemia, blood vessel blockages, and dangerously low blood pressure. Symptoms can include:

• Fever
• Pale or white gums
• Difficulty breathing
• Jaundice (yellowed eyes and skin)
• Low energy, depression
• Poor appetite
• Dehydration 
• Enlarged spleen and/or liver

These symptoms often progress rapidly to hypothermia, collapse, coma, and death. 

Unfortunately, severe disease and death are common with bobcat fever. In contrast, a few cats will only develop mild symptoms and recover completely. The severity of symptoms is thought to vary depending on the strain of the parasite and the overall health and immunity of the cat. If you are at all suspicious that your cat may have been exposed to a tick infected with C. felis, get your cat seen by a veterinarian right away. Supportive care can make the difference between life and death.

Diagnosing Bobcat Fever in Cats

A veterinarian will use a combination of oral history from you, a complete physical examination, and laboratory testing to diagnose bobcat fever.  If you know that your cat has been exposed to a tick-infested environment, it is important to let the veterinary care staff know. Laboratory testing will likely include blood and urine testing, and possibly testing for other infectious diseases that can cause similar symptoms. 

Bobcat fever is definitively diagnosed by seeing the blood parasite under the microscope on a fresh blood smear. There is also a PCR blood test available. Some cats may require bone or splenic aspirates to diagnose the disease.

Bobcat Fever Treatment in Cats

Bobcat fever treatment requires several days of hospitalization and aggressive supportive care. Most cats require fluid therapy. Some cats may require a blood transfusion, a chest tube to drain excess fluid, or a feeding tube. It depends on the severity of the symptoms and the cat’s response to care. Additional medications that may be prescribed to treat bobcat fever include:

• Antibiotics (atovaquone, azithromycin, enrofloxacin)
• Imidocarb dipropionate
• Atropine
• Heparin

Cost to Treat

Most cats with severe symptoms require three to seven days of hospitalized care. The cost to treat bobcat fever is high, usually costing several thousand dollars. 

Survival Rate

Unfortunately, even with aggressive supportive care and hospitalization, most cats with severe symptoms die from Bobcat fever. Without treatment, most infected cats die within five days of diagnosis. 

For the cats who do survive, however, the prognosis is good with a return to normal activity within two to four weeks after infection. These cats will enjoy immunity that will prevent re-infection of C. felis. 

How to Prevent Bobcat Fever in Cats

There is no vaccine available to prevent bobcat fever. Ask your veterinarian if bobcat fever, aka cytauxzoonosis, is present in your area. If you live in an area that has bobcat fever, the best way to protect your cat against bobcat fever is to keep them indoors to avoid tick exposure. 

If you do not keep your cat indoors, then it is strongly recommended to keep your cat on an effective, fast-kill flea and tick control product year-round. In addition to rigorous tick control medication, it is also recommended to check your cat daily for ticks. If you see any, promptly remove them. Douse the tick in alcohol, and save the tick in a closed plastic bag or jar, or take a high-resolution picture of the tick and dispose of it properly. 

In addition to daily tick checks and regular tick control medication, do your best to reduce ticks in your cat’s outdoor environment. This can be accomplished by removing debris and leaf piles, keeping shrubs and grass short and mowed, and using wildlife deterrents in your yard.

If your cat ever acquires a tick and then becomes sick afterward, be sure to take them to the veterinarian immediately. While the possibility of bobcat fever can be a scary proposition, take comfort that the disease is rare and can be prevented in most cats using the recommendations above.