Primary immune-mediated thrombocytopenia in cats.

Feline primary immune-mediated thrombocytopenia (pIMT) is a rare condition, and only a few cases have been described in veterinary literature. Five cats with severe thrombocytopenia most likely due to pIMT are described. A flow cytometry platelet-bound antibody test was positive in all cats; underlying diseases or triggering factors causing thrombocytopenia were not detected. Three cats were transfused with blood type-compatible fresh whole blood; one cat received Oxyglobin as well. All cats were treated with prednisolone; one cat received chlorambucil in addition. Four cats responded to treatment and were discharged from the hospital. One cat was euthanized due to dyspnea. Primary immune-mediated thrombocytopenia is rarely diagnosed in cats, but it is important as a differential diagnosis in cats presented with surface bleeding.