Therapeutic response analysis in dogs with naturally occurring osteoarthritis

Abstract Objective Reporting the rate of positive (+) and negative (–) responders based on an objective outcome measure of pain-related functional disability/lameness in dogs with naturally occurring osteoarthritis (OA), and the relationship between initial lameness severity and the odds of being a (+) responder. Study design Retrospective analysis of published peer-reviewed clinical trials in dogs with naturally occurring OA. Animals Dogs ( n  = 213) with hip and/or stifle afflicted-joints. Methods A responder analysis was undertaken using a previously determined cut-off value of ±2.0% of body weight using the peak of vertical force (PVF). Among the selected trials, PVF was acquired under similar conditions. Therapeutic approaches were therapeutic diets, natural health products and nonsteroidal anti-inflammatory drugs. Results Among dogs receiving a therapeutic approach as described above ( n = 121), 62.8% [95% confidence interval, 53.9–70.9] were defined as (+) responders, whereas 11.6% [7.0–18.5] were (–) responders, accounting for a net (+) response rate by 51.2% [42.0–60.4]. In dogs receiving a negative control ( n = 92), the net (+) response rate was 1.1% [0.0–5.9]. The number needed to treat was 4, and the effect size 0.7 [0.4–1.0]. The odds ratio of being a (+) responder under the therapeutic approaches was 2.85 [1.57–5.17] ( p p = 0.006). Conclusion and clinical relevance The rate of (+) responder optimizes decision making for the management of pain-related clinical signs of OA. Evidence-based medicine was further supported by clinical metrics based on an objective outcome measure of pain-related functional disability/lameness. This study also revealed that dogs with a mild lameness are less prone to be improved, emphasizing the need to carefully manage OA dogs in spite of a more subtle affliction.