Cytauxzoon in European cats: what a positive result means
4-year-old domestic shorthair from rural Castile and León with outdoor access and occasional ticks. It is healthy and is being assessed as a blood donor. The smear shows intraerythrocytic piroplasms and PCR is positive for Cytauxzoon spp.
Which statement is correct?
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A. In Europe many infections in domestic cats are subclinical and chronic, unlike C. felis in the USA; it should not be used as a donor
Correct. European species (such as C. europaeus), with the wildcat as reservoir, usually cause subclinical infections in domestic cats, although clinical cases have been described. An infected cat must not be a donor because transfusion transmits the parasite.
B. It is an acute disease that is almost always fatal within days, so the cat should be euthanised
That is the classic picture of C. felis in the southern USA (fever, jaundice, multiorgan failure). In European cats, and in a healthy cat, that decision has no basis.
C. It should be treated with imidocarb, which clears the infection with a single dose
Imidocarb has not been shown to be effective in cytauxzoonosis. In clinical C. felis infection, the treatment with the best results is atovaquone with azithromycin.
D. It is a zoonosis: the owners should be tested
Cytauxzoon is not considered zoonotic. It affects domestic and wild felids.
lightbulb Key takeaway
Piroplasms on a cat's blood smear may be Cytauxzoon or Babesia: identify the species by PCR. Screen donor cats from rural areas and use tick control in outdoor cats with products authorised for cats.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.