Retrospective assessment of toxicity associated with epirubicin chemotherapy in 66 tumour-bearing cats

Sixty-six cats received 186 epirubicin treatments for various tumours. Cats received a median of two treatments (range 1–7). The dose used was 1 mg/kg in all patients, with five patients having a dose escalation to 25 mg/m2 (19/186 treatments; 10%). Overall, 56% of cats exhibited possible toxicity, though differentiating toxicity from clinical signs of the underlying disease was not always possible. Anorexia and neutropenia, mostly VCOG grade 1–2 toxicities, were the most common. Only two events resulted in temporary hospitalization, and four cats (4/66; 6%) had treatment withdrawn due to adverse effects. Haematology after 7 days was performed in 43 cases and none showed neutrophil counts < 1 × 10^9/l. Serum BUN levels increased from pre-epirubicin levels in 11 cats (all grade 1 or 2) and creatinine increased from baseline in 3 of 52 cats (6%). Seven of 42 cats (17%) had increases in ALT (one grade 1, one grade 2, two grade 3 and three grade 4) though most were considered unlikely related to epirubicin. Future studies should focus on pharmacokinetics, establishing the maximum tolerated dose and defining the optimal spectrum of activity for clinical use.