Carprofen in Cats

Cats are more susceptible to the toxic effects of nonsteroidal antiinflammatory drugs (NSAIDs) because of their low capacity for hepatic glucuronidation, the main pathway for hepatic NSAID metabolism. However, NSAIDs are among the best analgesics for prevention and treatment of postoperative pain. Some published information suggests "off-label" pain management protocols for cats using meloxicam and carprofen, but no studies have investigated adverse effects of their long-term use in this species. To evaluate these adverse effects, 7 healthy cats were administered SC carprofen, 4 mg/kg (day 1), 2 mg/kg (days 2 and 3), and 1 mg/kg (days 4 and 6), or 0.35 mL of saline for 6 days, with no treatment given on day 5. Each cat served as its own control and was administered 2 treatments, each composed of a 1-week period with a 1-month washout period between them. A complete blood count, serum biochemical profile, and platelet aggregation, as well as endoscopy of the gastrointestinal tract, were performed before treatment and 7 days after treatment. No adverse clinical effects were noted in any cat, and endoscopy grading scores did not significantly differ between groups. Albumin values were lower at baseline than at day 7 in the carprofen group, and globulin and alkaline phosphatase values were higher at baseline than on day 7 in both groups. Serum alanine aminotransferase activity was increased at baseline but not on day 7 in 3 carprofen-treated cats and 3 saline-treated cats. No other changes in blood values were noted. The authors concluded that SC carprofen administered over 6 days does not adversely affect gastrointestinal, hematologic, or serum biochemical variables.

COMMENTARY: The use of NSAIDs for pain relief in small animals continues to increase. However, controversies remain as to the safety of this drug class in the perianesthetic period and with long-term use. Results of this study suggest that in healthy cats, a decreasing carprofen dose administered subcutaneously for 6 days had none of the adverse effects on organ systems (gastrointestinal, renal, hepatic, and hematologic) typically associated with NSAID toxicity. While the dosing schedule was empirically selected and efficacy (as the authors themselves acknowledge) was not evaluated, the authors provide a good review of factors that could influence toxicity of NSAIDs in the absence of a controlled setting.

Evaluation of the adverse effects of subcutaneous carprofen over six days in healthy cats. Steagall PVM, Moutinho FQ, Mantovani FB, et al. RES VET SCI 86:115-120, 2009.