Effect of analgesic therapy on clinical outcome measures in a randomized controlled trial using client-owned dogs with hip osteoarthritis

Sarah Malek, Susannah J Sample, Zeev Schwartz, Brett Nemke, Peer B Jacobson, Elizabeth M Cozzi, Susan L Schaefer, Jason A Bleedorn, Gerianne Holzman, Peter Muir

Pain and impaired mobility because of osteoarthritis (OA) is common in dogs and humans. Efficacy studies of analgesic drug treatment of dogs with naturally occurring OA may be challenging, as a caregiver placebo effect is typically evident. However, little is known about effect sizes of common outcome-measures in canine clinical trials evaluating treatment of OA pain. Forty-nine client-owned dogs with hip OA were enrolled in a randomized, double-blinded placebo-controlled prospective trial. After a 1 week baseline period, dogs were randomly assigned to a treatment (ABT-116 - transient receptor potential vanilloid 1 (TRPV1) antagonist, Carprofen - non-steroidal anti-inflammatory drug (NSAID), Tramadol - synthetic opiate, or Placebo) for 2 weeks. Outcome-measures included physical examination parameters, owner questionnaire, activity monitoring, gait analysis, and use of rescue medication.