Poikilocytosis in dogs with chronic doxorubicin toxicosis

Peripheral blood smears made during 2 studies of chemical antidotes for doxorubicin (DRB) cardiotoxicity in dogs were examined to determine the incidence of poikilocytosis. The 1st study had significantly (P less than 0.05) increased numbers of poikilocytes in 3 groups of 5 dogs, each treated with DRB alone, DRB plus thyroxine (0.5 mg/day), and DRB plus thyroxine (2.0 mg/day), respectively, compared with 1 group of 5 dogs treated with thyroxine alone (2.0 mg/day). In addition, the DRB-treated dogs had regenerative anemia characterized by an increased reticulocyte index. The 2nd study had a significant (P less than 0.05) increase in poikilocytes in 4 groups of 6 dogs, each treated with DRB alone, DRB plus +/- -1,2-bis(3-5-dioxopiperazinyl-1-yl; ICRF-187), DRB plus N-acetylcysteine (NAC), and drb plus ICRF-187 plus NAC, respectively, compared with 4 groups of 3 dogs, each treated with ICRF-187 plus saline solution (SS), NAC plus SS, ICRF-187 plus NAC plus SS, and SS alone, respectively. In both studies, the poikilocytes were identified as echinocytes, spiculated erythrocytes, and schizocytes. Administration of thyroxine and ICRF-187 did not prevent the occurrence of poikilocytosis in DRB-treated dogs. Administration of NAC with DRB resulted in a mild decrease in the extent of poikilocytosis compared with that observed in dogs given DRB alone. The hematologic changes observed in both studies were not accompanied by adverse clinical signs referable to the DRB-induced alterations in erythrocytes.