This study assessed the analgesic effects of amantadine, in combination with meloxicam, in dogs with osteoarthritis.

Thirty-one client-owned dogs with clinical hind limb lameness despite the use of a non-steroidal anti-inflammatory drug (NSAID) were included. The study was randomized, blinded and placebo controlled with parallel groups. On day 0, dogs were taken off all medications. On day 7, all dogs received meloxicam (approved dosing regimen) for 5 weeks. On day 21, dogs received amantadine (A) (3-5mg/kg once daily per os) or placebo (P) for 21 days, in addition to receiving meloxicam. Assessments were performed on days 0 (prior to study), 7, 21, and 42. Primary outcome measures were blinded owner assessments of activity using client specific outcome measures (CSOM) (days 0, 7, 21 and 42). Data was analyzed using Wilcoxon Signed Rank test.

Both groups improved significantly from day 7 to 21 in CSOM scores for activity. From day 21 to 42, the amantadine group improved further (p=0.0002), but the placebo group did not (p=0.87). In dogs with osteoarthritis pain partly refractory to a NSAID, the ability to perform everyday activities is improved by the addition of amantadine.