Osteoarthritis (OA) being the most common degenerative disease in pets, a large panel of natural health products (NHPs) is available for its management. This systematic review aim was to examine the evidences of NHPs to present a solid analgesic efficacy, and correctly disseminate the conclusions about their therapeutic potential.

Four bibliographic databases were searched to identify studies testing the effectiveness of nutraceuticals on canine and feline, natural or induced, osteoarthritis. After screening of search results against eligibility criteria, data were extracted using an evaluation grid based on the ARRIVE (Animal Research: Reporting of In Vivo Experiments) and CONSORT (Consolidated Standards of Reporting Trials) guidelines and the CAMARADES tool. The trials were assessed for the risk of bias, methodological quality and strength of evidence for efficacy (or non-effect). Results were reported according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

Fifty-five articles were included, comprising 70 trials divided into 7 categories. Overall, the risk of bias and methodological quality was homogeneous between the categories. For the strength of evidence, therapeutic diets as well as nutraceuticals like green-lipped mussels (GLM)/omega-3 supplements, and phytotherapy were elevated. For analgesic efficacy, GLM/omega-3 enriched diets or supplements were the most convincing; cannabidiol looked attractive; whereas symptomatic slow-acting agents such as glucosamine/ chondroitin were presenting strong evidence of no effect in OA pain management.

Clinical testing of NHPs in pets affected by OA, as assessed in this review, highlights the strong evidence of efficacy for GLM/omega-3 supplements or enriched therapeutic diets. Cannabidiol is promising. Glucosamine/chondroitin formulations present poor interest and must not be considered to manage OA pain for pet animals.