Evidence Update- A new Systematic Review of Diets & Dietary Supplements for Arthritis in Dogs and Cats (TLDR- Can we please stop giving them glucosamine?!)

One of the most common topics over the lifetime of this blog has been treatments for osteoarthritis in dogs and cats. I’ve talked about pharmaceuticals, acupuncture, electromagnetic fields, laser, and other treatments, but the bulk of the articles have addressed the most popular over-the-counter (OTC) remedies for this condition, dietary supplements.

Supplements are ubiquitous, recommended by vets and used by owners frequently despite scientific evidence that is inconclusive or that outright shows they don’t work. Over the time I have been covering this topic, science-based medicine has provided new tools for treating arthritis, such as the use of monoclonal antibodies to reduce pain and inflammation in dogs and cats. For most pets, non-steroidal anti-inflammatory medications (NSAIDs) also remain a safe and effective treatment. There are also promising approaches, such as CBD and physical therapy, that have some encouraging supportive evidence, though more research is certainly needed for these. Despite this, pet owners, and even vets, have a tendency to stick with outdated OTC remedies that are unproven or even clearly ineffective.

The paragon for this is glucosamine/chondroitin. I wrote about the poor evidence supporting use of this supplement in arthritis pets in the very first month of this blog, June, 2009. At that time, I stated-

There is virtually no good quality research on the use of glucosamine and chondroitin in veterinary patients. The best study so far, done in dogs, found a combination of these agents to be of no benefit for patients with osteoarthritis. Further research in animals with osteoarthritis is warranted, but at this time the evidence does not support the use of glucosamine and chondroitin in these patients.  

Since then, the negative evidence has piled up, in humans and in animals. My most recent summary in 2020 concluded-

The failure to find consistent and compelling evidence of clinically meaningful benefits after decades of extensive research strongly suggests such benefits are negligible or nonexistent. 

Despite the seemingly minimal impact of such consistently negative findings on pet owner behavior, I feel obliged to continue to review the evidence and encourage both vets and owners to use therapies with real evidence of safety and benefit whenever possible. A recent systematic review (the highest level of evidence available) has once again looked at glucosamine, along with a host of other diets and dietary supplements for arthritis in dogs and cats, and hopefully their findings will shift the zeitgeist a bit on how we manage this condition.

Barbeau-Grégoire M, Otis C, Cournoyer A, Moreau M, Lussier B, Troncy E. A 2022 Systematic Review and Meta-Analysis of Enriched Therapeutic Diets and Nutraceuticals in Canine and Feline Osteoarthritis. Int J Mol Sci. 2022 Sep 8;23(18):10384. 

The figure below illustrates the quality of evidence for five categories of potential therapies. The proportion of studies showing the highest level of evidence, an effect compared with a placebo (Effect), an intermediate level of support, improvement over time without such a comparison (Improvement), or no effect at all (Non-effect) are shown.

The authors also evaluated the number and methodological quality of the research showing these effects and provided conclusions on each intervention. Here are those conclusions-

This meta-analysis supports the use of omega-3 supplementation for the management of canine and feline OA.

The results of this meta-analysis [for cannabis] are promising, but further investigation is needed to determine the efficacy, doses, formulations and combinations recommended for the treatment of canine OA pain. Further studies will also be necessary to conclude on the use of cannabinoids in cats since none have been carried out to this day.

It, therefore, appears impossible to rule, at the present time, on an indication for collagen in canine OA based on the results of this meta-analysis.

Like these previous reviews, the results of the present meta-analysis led to the conclusion that chondroitin-glucosamine nutraceuticals should not be prescribed in canine or feline OA.

All the other nutraceuticals evaluated did not present sufficient evidence of efficacy to decide on their indication.

I am not naïve enough to imagine that this will lead to a widespread abandonment of glucosamine, but I hope that the consistent buildup of evidence over decades showing that this is an ineffective treatment, and the active recommendations against it by experts in both human and veterinary medicine, will at least discourage the substitution of this failed approach for treatments with much better evidence for real effects.