Hematologic and serum biochemical effects of long-term administration of anti-inflammatory doses of prednisone in dogs.

Results of routine hematologic and serum biochemical analyses from 12 healthy adult male dogs that were given prednisone (0.55 mg/kg of body weight, PO, q 12 h) for 35 days were compared with those of a control group of 6 dogs that were given gelatin capsules. Analyses were performed at 2-week intervals during and after prednisone administration. Lymphocyte and eosinophil counts were significantly (P less than 0.005) decreased after 2 and 4 weeks of prednisone treatment, compared with controls. Two weeks after treatment, eosinophil counts in prednisone-treated dogs were similar to those of control dogs, whereas lymphocyte counts remained low 4 weeks after treatment in treated dogs (1,869 +/- 145 cells/microliters), compared with that in control dogs (3,662 +/- 548 cells/microliters). Neutrophil and monocyte counts did not significantly change during glucocorticoid administration. Mean platelet volume significantly (P less than 0.001) decreased after 4 weeks of prednisone treatment, but returned to pretreatment values by 2 weeks after treatment. Four weeks of prednisone treatment did not cause significant increased activity in serum alanine transaminase, total alkaline phosphatase or the steroid-induced isoenzyme of alkaline phosphatase. Significant increases in serum albumin (P less than 0.001) and total protein (P less than 0.05) concentrations were detected after 4 weeks of treatment, but mean values were not significantly different from those of controls 2 weeks after treatment ended. Results of our study indicate that eosinophil and lymphocyte counts are the most sensitive indicators of long-term glucocorticoid administration at anti-inflammatory dosages of 1.1 mg/kg daily.