Orthopedic Surgery-Associated Pain in Cats

NSAIDs are used widely in veterinary medicine; however, few are approved for use in cats. Robenacoxib (Onsior, onsior.com), a cyclooxygenase-2 (COX-2)–selective NSAID, is registered for use in dogs and cats and is available in oral and injectable formulations. Robenacoxib is considered relatively safe in cats, likely because of its COX-2 specificity, short half-life (≈1.5 hours), and blood and selective tissue distribution. This study sought to compare the efficacy and safety of robenacoxib with meloxicam (also a preferential COX-2 inhibitor with a longer half-life) in controlling perioperative pain and inflammation associated with orthopedic surgery in cats. In this multicentered, prospective, randomized, blinded study, 101 cats (Group 1) received subcutaneous robenacoxib (2 mg/kg) preoperatively, followed by oral robenacoxib (1.0-2.4 mg/kg) for 9 days postoperatively. Group 2 cats(n = 46) received 0.3 mg/kg meloxicam SC preoperatively, followed by placebo tablets for 9 days postoperatively. (Meloxicam was not registered for postoperative use in cats.) Rescue analgesics were given as needed. Cats were assessed using numerical rating scales preoperatively, acutely postoperative, and at the final visit (day 10). A single preoperative robenacoxib injection was found statistically equivalent (“noninferior”) to meloxicam in efficacy. During the follow-up period, no significant difference in outcome was found between groups, and no significant differences were noted in reported adverse events, clinical observations, hematology, or clinical chemistry. The authors concluded that robenacoxib is noninferior to meloxicam in controlling pain and inflammation associated with orthopedic surgery in cats. All authors were employees of Novartis Animal Health, now owned by Elanco Animal Health, which manufactures and distributes robenacoxib (Onsior).

Cats have pain of inflammation, and anti-inflammatory drugs are clearly the best choice for treating that pain. However, inappropriate NSAID dosing has scared many practitioners in the United States away from this drug class. Dosing meloxicam once at the label dose (0.3 mg/kg) provides measurable serum concentrations for approximately 92 hours.1 Thus, a 1-time dose is appropriate. A lower dose administered more often may also be appropriate.^2,3 Robenacoxib is a welcome addition to the NSAID-for-cats armament, and the ability to provide repeated dosing may provide more consistent analgesia. Dosing for 9 days is a great start, and determining the safety and efficacy of robenacoxib administered for chronic pain would be an excellent next study. NOTE: In the United States, robenacoxib is not available as an injectable drug, and the oral dosing label recommendation is 3 days.—Tamara Grubb, DVM, PhD, DACVAA