Short-Term Effects of Meloxicam and Marine-Based Fatty Acid Compounds on Objective Limb Loading and Owner-Reported Outcomes in Dogs with Hip Osteoarthritis: A Randomized, Double-Blind, Placebo-Controlled Trial

Canine hip osteoarthritis (OA) requires multidimensional assessment. This randomized, double-blind, placebo-controlled trial evaluated 4-week treatment with meloxicam, PCSO-524, EAB-277, meloxicam plus PCSO-524, or placebo in 203 client-owned dogs with naturally occurring hip OA. The principal outcome was index-hindlimb peak vertical force (PVF) measured by force-plate gait analysis. Secondary outcomes included PVF responder status, orthopedic assessment score (OAS), Liverpool Osteoarthritis in Dogs (LOAD), Canine Brief Pain Inventory (CBPI), and safety assessments. The primary baseline-adjusted mean PVF analysis did not demonstrate treatment superiority among groups. A secondary responder analysis using an analysis-stage >5%BW PVF threshold showed that meloxicam had a nominally higher Week 4 responder probability than placebo (relative risk = 4.000; 95% confidence interval, 1.223 to 13.079; p = 0.022), interpreted as supportive rather than confirmatory. Within-group score reductions were observed in LOAD and CBPI pain interference for the combination group, LOAD for PCSO-524, and CBPI pain interference for EAB-277. OAS did not change significantly within any group. Between-group differences in LOAD and CBPI changes were not significant. No consistent group-level laboratory safety concern was detected. These findings support multidimensional assessment while emphasizing that secondary results do not establish treatment superiority.