Lack of Treatment Efficacy of Tramadol on Pain and Dysfunction of Chronic Osteoarthritic (OA) Joints in Dogs

Introduction: Tramadol has grown both as a primary and supplementary medication for the pain and dysfunction of osteoarthritis (OA) in dogs despite an absence of supportive clinical data and in the presence of unfavorable pharmacologic data. The goal of the present study was to investigate the efficacy of tramadol in dogs with OA in a blinded, prospective clinical trial. Hypothesis being tested was that tramadol would not be efficacious for the treatment of pain and dysfunction in dogs with OA.

Methods: A prospective, randomized, blinded crossover, placebo-controlled clinical trial was performed. Forty dogs met inclusion criteria and all owners signed a written informed consent prior to study initiation. Documentation (clinically and radiographically) of OA in at least one elbow or stifle was required. Three treatments were randomly assigned: (1) placebo, (2) carprofen (2.2 mg/kg–q 12 hours), and (3) tramadol (5 mg/kg–q 8 hours). Regardless of treatment, dogs received indistinguishable capsules every 8 hours during each treatment period. There was a minimum 7-day washout period between treatments. Ground reaction forces (GRF) were measured prior to and at the end of each treatment. A repeated measured ANOVA was used to evaluate data.

Results: Peak vertical force (PVF) and vertical impulse (VI) data revealed no significant increases during placebo or tramadol treatment compared with baseline. Carprofen significantly increased both PVF and VI values compared with baseline. Carprofen significantly increased PVF and VI compared with placebo and tramadol.

Discussion: Tramadol provided no efficacy and GRF values were not significantly different from placebo in dogs with OA.

Acknowledgement: This study was supported, in part, by a grant from the Morris Animal Foundation (Grant D15CA-030).