Idiopathic thrombocytopenic purpura in a cat

An 11-year-old, castrated, male domestic shorthair cat was presented for he maturia and pollakiuria, The cat had a marked thrombocytopenia, and a bone- marrow core biopsy demonstrated megakaryocytic hyperplasia with many megaka ryocyte-associated neutrophils (i.e., emperipolesis). On peripheral blood, collected at initial presentation, what appeared to be platelets were noted to be within or adherent to occasional neutrophils. The thrombocytopenia w as idiopathic in that no definitive cause could be found, However, platelet concentrations appeared to increase and decrease in response to changes in prednisone and cyclosporine therapy, suggesting a possible immune-mediated pathogenesis, As tests to detect increased feline platelet-associated anti bodies are unavailable, immune-mediated thrombocytopenia can only be tentat ively diagnosed in cats by exclusion and response to therapy.