ISSN 2398-2950      

Cytauxzoon felis


Leah Cohn

Susan Dawson




  • Order: Piroplasmida.
  • Family: Theileriidae.
  • Genus: Cytauxzoon.
  • Species: felis.


  • Protozoon.

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Clinical Effects



  • Central and southeastern United States.
  • Affects cats that have exposure to ticks, often near wooded areas.


  • Wildlife reservoir hosts (eg, bobcats).


  • Tick-borne disease. Dermacentor variabilis  Dermacentor variabilis is demonstrated competent tick vector.
  • Cat to cat transmission does not occur, even with close contact between cats.

Pathological effects

  • The tissue phase leads to large numbers of parasitized macrophages lining the veins and leading to obstruction and thrombi formation.
  • The lungs, liver, spleen, lymph nodes, and bone marrow are particularly susceptible to parasitism and tissue damage.
  • The tissue phase of development is associated with the development of disease.
  • Cats that survive the shizogenous tissue phase of infection can maintain an erythrocytic phase of infection without clinical illness. Similarly, cats inoculated with erythrocytes containing piroplasms do not develop clinical illness but remain carriers of infection.
  • Disseminated intravascular coagulation Disseminated intravascular coagulation is a common complication.


Control via animal

Control via chemotherapies

  • There are no chemotherapeutic interventions with proven efficacy, and infection with C. felis is usually fatal despite treatment.
  • Anecdotal reports describe successful treatment with 2 i.m. injections of diminazene aceturate or imidocarb dipropionate (2 mg/kg [0.9 mg/lb] of body weight, each) although controlled studies have not confirmed the efficacy of these treatments. Additional supportive treatments were also given to all surviving cats. If imidocarb is used, cats should receive atropine Atropine pretreatment to lessen adverse cholenergic effects of therapy.
  • Supportive therapy is vital, and includes:
  • Often, broad spectrum antimicrobials Therapeutics: antimicrobial drug are administered to prevent secondary bacterial infection.

Other countermeasures

  • Application of products to prevent feeding of ticks.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Ketz-Riley C J, Reichard M V, Van den Bussche R A et al (2003) An intraerythrocytic small piroplasm in wild-caught Pallas's cats (Otocolobus manul) from Mongolia. J Wildl Dis 39 (2), 424-430 PubMed.
  • Greene C E, Latimer K, Hopper E et al (1999) Administration of diminazene aceturate or imidocarb dipropionate for treatment of cytauxzoonosis in cats. J Am Vet Med Assoc 215 (4), 497-500, 482 PubMed.
  • Hoover J P, Walker D B & Hedges J D (1994) Cytauxzoonosis in cats: eight cases (1985-1992). J Am Vet Med Assoc 205 (3), 455-460 PubMed.
  • Harvey J W, Franks P T, Shields R P et al (1987) Hematologic findings in experimental cytauxzoonosis. Veterinary Clinical Pathology 16 (1), 7 VetMedResource.
  • Kier A B, Wagner J A & Kinden D A (1987) The pathology of experimental cytauxzoonosis. J Comp Pathol 97 (4), 415-432 PubMed.

Other sources of information

  • Kier A B & Greene C E (1998) Cytauxzoonosis. In: Infectious diseases of the Dog and Cat, ed. CE Greene, WB Saunders Company. pp 470-473.

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