Cytauxzoonosis and Atovaquone

Cytauxzoonosis is an infection caused by a protozoal hemoparasite called Cytauxzoon felis. The protozoan is transmitted by Ixodid ticks that ingest infected blood or tissue cells. The parasite has been seen in southeastern and south-central states of the United States more commonly during months of April through September. Cats living near heavily wooded, low-population residential areas that is in close proximity to natural habitats where bobcats and ticks are found more prevalent. Typically the primary vector for Cytauxzoon felis is the North American bobcat where they are typically asymptomatic. However, in domestic cats this infection often proves fatal since clinical signs progress to mortality quickly without many effective treatment plans. These infected cells can affect white blood cells and cause occlusions and ultimately death. Diagnosis often made with classic signet ring shaped merozoites present on blood smear test (Cohn, 2010). 

One effective treatment has been concomitant therapy of Atovaquone and Azithromycin. A prospective study found 60% survival rate as opposed to common alternative therapy Imidocarb at 26% (Cohn, 2010). Both of these medications can be compounded into flavored suspension that could very well save an animal’s life if initiated promptly. Being aware of this potential infection could save some unfortunate clientele.

Dosing: Atovaquone 15mg/kg by mouth every 8 hoursX10 days

            Azithromycin 10mg/kg by mouth every 24 hoursX10 days

Cohn, L., Birkenheuer, A., Brunker, J., Ratcliff, E. and Craig, A. (2011), Efficacy of Atovaquone and Azithromycin or Imidocarb Dipropionate in Cats with Acute Cytauxzoonosis. Journal of Veterinary Internal Medicine, 25: 55-60. doi:10.1111/j.1939-1676.2010.0646.x