Fergus Survives Cytauxzoonosis -- aka Bobcat Fever

Cytauxzoonosis or Bobcat Fever has been aptly described as Ebola for domestic cats. The disease is endemic and nonfatal in bobcats, but is far more deadly among smaller cats. It was first observed in Missouri in 1976 and killed over 90% of infected felines. It has since spread from Florida to North Dakota and as far east as Pennsylvania.

Lone Star Tick

The disease is caused by a protozoan parasite named Cytauxzoon and is spread primarily by the lone star tick. During a certain stage of development, these protozoa gum up the smaller vessels in the cat's circulatory system, eventually causing multiple organ failures and an agonizing death. The initial symptoms are lethargy and (at least in our cat Fergus) the vomiting of clear bile at intervals of several hours.

I first noticed Fergus vomiting sometime during the night of Friday, May 24. Since Fergus often goes out to eat grass and then comes inside before throwing up, I didn't make much of it--except for being mildly surprised by the absence of grass in the bile. By Sunday morning he had vomited several more times and was dozing continually. I isolated him with a clean litter box and set out measured amounts of food and water to see if he was seriously ill. He didn't eat or drink, and when he vomited a few more tablespoons of clear bile at 6:30 pm without even having the energy to get off the bed, we put in an emergency call to our veterinarian, Dr. Christina White of the Animal Health Center in Mountain Home, Arkansas.

By 7:30 pm she was treating him. He had a fever of over 107 degrees (about 100 is normal in cats), and she immediately suspected Bobcat Fever. She put him on an intravenous drip to begin hydrating him in an effort to bring down the fever. She also took a blood sample and examined a smear under a microscope in order to confirm her diagnosis.

Note  the shaved patch where the IV was attached

Only three years ago Fergus would have been doomed at this point. Among animals whose temperature exceeded 106 degrees, the survival rate was minuscule, and death was expected within one to three days. The most humane treatment would have been euthanasia.

Fortunately, in 2010 a pair of veterinarians from the University of Missouri published a paper about a promising new treatment of Cytauxzoonosis, involving hospitalization, hydration, and aggressive treatment with the antimalarial drug Atovaquone and the antibiotic Azithromycin. They reported a survival rate of approximately 60%.

Fergus remained hospitalized until Wednesday, and then we brought him home with our precious vials of Atovaquone and Azithromycin to continue his treatments for another week--1.7 cc of Atovaquone every 8 hours and 1 cc of Azithromycin daily, administered by prying his mouth open and squirting the doses down his throat with a syringe.

Although he seemed entirely cured as soon as he was released from the pet hospital, we were aware of the need to be sure that no more protozoa were developing in his blood system and that he did not develop any secondary infections as a result of the circulatory stress and potential  organic damage. Only now can we begin to breath easy.

Fergus has gone from being a pampered pet who treasured the beauty of an Arkansas spring to an even more appreciated pet who is already seeking out more cerebral indoor enjoyments like card games and music.

Further Information:
http://www.merckmanuals.com/vet/circulatory_system/blood_parasites/cytauxzoonosis.html

http://www.sciencedaily.com/releases/2012/04/120418162258.htm

http://www.examiner.com/article/most-cats-with-bobcat-fever-saved-by-new-treatment

http://www.catster.com/the-scoop/house-cats-falling-prey-to-bobcat-fever