Serum Erythropoietin Concentrations Measured by Radioimmunoassay in Normal, Polycythemic, and Anemic Dogs and Cats

Serum erythropoietin (Epo) concentrations were measured by radioimmunoassay (RIA) in normal, polycythemic, and anemic dogs and cats. The serum Epo concentration in normal dogs ( n = 25) ranged from 7 to 37 mU/mL (median, 20 mU/mL); and in normal cats ( n = 11) ranged from 9 to 38 mU/mL (median, 18 mU/mL). Polycythemic animals (PCV < 55% in dogs, > 45% in cats) were classified as those with primary (polycythemia vera), secondary, or polycythemia of uncertain etiology. Dogs with polycythemia vera (PV, n = 8) had a median serum Epo concentration in the normal range (17 mU/mL); cats with PV ( n = 7) also had a median serum Epo concentration that was within the normal range (10 mU/mL). In the category of secondary polycythemias, dogs ( n = 7) (median, 30.7 mU/mL) and cats ( n = 2) had normal Epo concentrations. The median serum Epoconcentration was significantly decreased ( P > .05) in dogs with PV compared with dogs with secondary polycythemias. The median serum Epo concentrations in dogs ( n = 13) and cats ( n = 5) with anemias not due to chronic renal disease were significantly increased ( P > .05) compared with normal dogs and cats. In cats with anemias due to chronic renal disease ( n = 5) the median serum Epo concentration was not significantly different from normal cats. The measurement of the serum EPO concentration may be useful in assessment of anemia or polycythemia but the overlap of values with the normal range in all groups evaluated limit its diagnostic use.