Serum erythropoietin values in polycythemic cats.

Serum erythropoietin (EPO) concentrations and clinicopathological features were evaluated in 31 cats with absolute polycythemia (i.e., packed cell volume [PCV], 52% to 84%). Five cats had high serum EPO values and were classified as having secondary polycythemia. The remaining 26 cats had EPO values in the low or normal range. Four of these 26 cats had clinical evidence of secondary polycythemia and therefore were classified as having secondary polycythemia. In the remaining 22 cases, no signs of secondary polycythemia could be found, and primary polycythemia was diagnosed. A low or normal serum EPO value in a polycythemic cat is consistent with primary polycythemia, but does not exclude secondary polycythemia.