is not enough information to prove any of these theories, but cats in the same household or same regions can have drastically different clinical presentations. Some studies even show multi-cat households have had one cat die and another be persistently infected. When cats survive infection they have persistent parasitemia which shows up in the blood as piroplasms, but these cats do not have the tissue phase again and therefore do not again show the clinical illness. Diagnosis One way to diagnose C. felis is by taking blood and performing a peripheral blood smear to look for the erythrocytic piroplasms. The erythrocytic piroplasms are usually shaped like signet rings and are 1 to 1.5 µm. Not all cats that are infected will have the piroplasms on their blood smear, especially if they are early in disease course. Another method of diagnosing infection in sick cats is to take needle aspirates of affected organs and find the schizonts inside mononuclear cells in the tissues; examination of tissue is also useful for the diagnosis after cats have died. Blood samples can be sent away for polymerase chain reaction (PCR) testing to confirm infection. Other diseases that might resemble cytauxzoonosis should be ruled out. A major rule-out for C. felis is Mycoplasma haemofelis (formerly known as Haemobartonella felis); clinical signs can be similar to cytauxzoonosis and the organism may be confused on the peripheral smear. Because it causes similar signs in outdoor cats during the spring and summer, tularemia is another disease the veterinarian may want to rule out. Other laboratory tests are often abnormal in sick cats. The CBC of an infected cat often shows a pancytopenia, or a decrease in red blood cells, white blood cells, and platelets; in some cases there is not a decrease in all three values. Clotting tests may be prolonged. Increased liver enzymes are common, and electrolyte disturbances, hyperglycemia, and acid-base disturbances can also be observed. Treatment and prevention The preventative measure of keeping cats inside in areas with high infection rates can prevent infection. Approved tick treatments for cats can be used but have been shown not to fully prevent tick bites. The most often used treatments for cytauxzoonosis are imidocarb dipropionate and a combination of atovaquone and azithromycin. Although imidocarb has been used for years, it is not particularly effective. In a large study, only 25% of cats treated with this drug and supportive care