Arthritis, Blog, Supplements
The best joint supplements for dogs with arthritis (what the science actually says)
Arthritis is one of the most common health problems affecting older dogs. Stiffness after rest, reluctance to jump, and slower walks can all be signs that joints are becoming painful. When this happens, many dog owners naturally start searching for joint supplements. From glucosamine chews to collagen powders and fish oil capsules, there is no shortage of products marketed to support joint health and help dogs with arthritis.
These products are often expensive, and the promises on the packaging can sound very convincing. But when we look past the marketing, an important question remains: do joint supplements actually help dogs with arthritis?
To best answer that question, we need to look at the best available evidence – not just individual studies, but research that brings the full picture together. One of the most reliable ways to do this is through a systematic review.
What is a systematic review?
(and why is this type of research so valuable when choosing a joint supplement for your dog)
Rather than testing a single treatment in one study, a systematic review takes a much bigger view. Researchers search the scientific literature for all the studies on a particular question, carefully evaluate the study quality, and then bring the findings together to see what the overall evidence shows.
Think of it like a jury hearing a case. Rather than relying on the testimony of a single witness, the jury listens to all the available evidence, considers how reliable each piece is, and then makes a judgment based on the overall picture. That is essentially what a systematic review does with scientific studies.
Now, let’s look at a systematic review from 2022. In this review, the researchers identified more than 1,500 studies investigating joint supplements and therapeutic diets for dogs with osteoarthritis.
After carefully screening and evaluating the studies, they included:
- 57 scientific papers
- 72 clinical trials (within those papers)
- 38 different supplements or compounds
The products were then grouped into 5 main categories:
- omega-3-enriched therapeutic diets
- omega-3 supplements (fish oil, green-lipped mussels)
- collagen supplements
- cannabinoid (CBD) products
- glucosamine and chondroitin supplements
So, with all this research on the table, what did the overall evidence show – which joint supplements truly made a difference for dogs with arthritis?
Omega-3 fatty acids for dogs with arthritis
Verdict: Strong and consistent evidence.
Omega-3 fatty acids work by reducing joint inflammation, which in turn improves both comfort and mobility – and of all the joint supplements, they stood out most clearly.
Both omega-3 supplements (such as fish oil) and diets formulated with higher levels of omega-3 fatty acids showed some of the strongest and most consistent evidence of benefit in dogs with osteoarthritis. Across the trials analysed, most studies reported improvements in pain and mobility in dogs receiving omega-3s. In fact, only 2 of the omega-3 trials failed to show a benefit, highlighting the consistency of the findings.
Importantly, many of the omega-3 studies were considered higher-quality than those in some other supplement categories, which strengthens the reliability of these results.
The omega-3 fatty acids most commonly researched are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These are long-chain fatty acids typically found in fish oils and fatty fish. Other forms of omega-3, such as ALA (alpha-linolenic acid), also exist, but these must first be converted into EPA and DHA before the body can make use of them – something a dog’s body does not do very efficiently.
The amounts of EPA and DHA used in arthritis studies are typically much higher than standard maintenance doses. Because excessive intake can cause issues such as gastrointestinal upset, altered clotting, and nutrient imbalances, it’s important to discuss dosing with your vet or a qualified nutritionist before starting fish oil for your dog.
When choosing a product, look for an unflavoured option with a high EPA and DHA concentration per mL. Capsules are often preferable to bottled oils, as they are better protected from air and light and therefore less prone to oxidation (rancidity).
If your dog doesn’t tolerate fish oil, algae-based omega-3 supplements can be a suitable alternative.
Green-lipped mussel for dogs with arthritis
Verdict: Potential benefits, but limited evidence
Green-lipped mussel (Perna canaliculus) is derived from a mussel native to New Zealand and contains a mixture of nutrients, including omega-3 fatty acids, glycoproteins and amino acids.
In the 2022 review, green-lipped mussel was included within studies evaluating omega-3-rich diets and supplements, rather than being assessed separately. As part of this group, it contributed to some of the strongest evidence in the review. However, because it was not evaluated as a category in its own right, it is difficult to draw firm conclusions about its effects in isolation.
Some clinical studies have reported improvements in pain and mobility in dogs with osteoarthritis following supplementation with green-lipped mussel only. However, the evidence is inconsistent, with other studies finding little or no measurable benefit.
Cannabidiol (CBD) for dogs with arthritis
Verdict: promising, but the evidence is still developing.
Cannabidiol (CBD) supplements have become increasingly popular in recent years, particularly for managing chronic pain in dogs. In the review, most studies reported improvements in dogs with osteoarthritis receiving CBD compared with those given a placebo.
However, the number of studies remains relatively small, and researchers emphasised that more high-quality trials are needed before clear recommendations can be made.
Collagen supplements for dogs with arthritis
Verdict: limited evidence
Collagen supplements are often marketed to support joint cartilage and improve joint health in dogs. The review found that the evidence supporting the use of collagen in dogs with arthritis was limited and of low quality. Many of the studies were small and relied on owner questionnaires rather than objective measures such as gait analysis.
Because of these limitations, the researchers concluded that it is currently difficult to draw firm conclusions about the effectiveness of collagen supplements for dogs with arthritis.
Glucosamine and chondroitin for dogs with arthritis
Verdict: Little to no benefit
Perhaps the most surprising finding of the review relates to glucosamine and chondroitin – two of the most widely used ingredients in canine joint supplements.
They are commonly included in products marketed to support joint health, protect cartilage, and improve mobility. Many owners are familiar with them, and they are frequently recommended in veterinary practice.
However, when researchers analysed the available evidence, the results were far less encouraging.
Across the trials included in the review, glucosamine and chondroitin showed little evidence of meaningful pain relief in dogs with arthritis. In fact, nearly 90% of the studies found no significant benefits.
When the researchers combined the results and accounted for the quality of the trials, glucosamine and chondroitin performed significantly worse than the other supplement categories examined.
Based on this analysis, the authors concluded that glucosamine and chondroitin should not be recommended for the management of osteoarthritis in dogs.
This raises an obvious question…
If the evidence is weak, why are glucosamine and chondroitin still so popular?
There are several possible explanations.
First, arthritis symptoms naturally fluctuate over time. Dogs may have good days and bad days, and improvements may occur regardless of whether a supplement is being used. When a supplement is started during a period when symptoms happen to improve, it is easy to attribute that improvement to the product.
Second, many studies and real-world observations rely on subjective assessments, such as owner questionnaires. While these can provide useful insights, they are also more susceptible to bias. When owners hope a supplement will help their dog, they may unintentionally see improvements that are difficult to objectively measure. This is sometimes referred to as the placebo effect or observer bias, where an owner’s hope that a supplement will work influences how they interpret their dog’s behaviour.
Third, glucosamine is involved in cartilage biology, which makes the theory behind it sound convincing. Laboratory studies have suggested it may influence inflammatory pathways or cartilage metabolism. However, results seen in laboratory experiments do not always translate into meaningful clinical improvements in real animals. One possible explanation is bioavailability. When given orally, glucosamine and chondroitin appear to be poorly absorbed in dogs (reported at approximately 12% and 5% after a single dose). That means only a small fraction may reach circulation, and potentially the joint, in relevant amounts.
Finally, there is what might be called the “it can’t hurt” mentality (or more formally, action bias). Because glucosamine and chondroitin for dogs are generally considered safe, many veterinarians recommend them on the basis that even if the benefits are uncertain, the risk is low. There is also a natural human tendency, in both owners and clinicians, to want to feel that something is being done, particularly when a dog is in pain and options feel limited.
Hang on… Why do some manufacturers claim there is evidence if there is none?
This is a really important question, and the answer is a bit nuanced. Companies that sell joint supplements are not necessarily inventing research, but the way the evidence is interpreted and presented can be quite different from how it is evaluated in systematic reviews.
There are several reasons why companies can claim there is “research supporting” glucosamine and chondroitin.
Some individual studies do report positive results. Certain small trials or studies using subjective outcome measures (e.g. owner questionnaires as opposed to objective measurements such as gait analysis or activity monitoring) have found improvements in dogs receiving glucosamine-containing supplements. Companies often highlight these studies when marketing their products.
However, when researchers analyse all the studies together (as in our 2022 systematic review), the overall picture becomes much clearer. Many studies show no effect, and when the quality of the trials is taken into account, i.e. owner questionnaires rather than objective measurements, the evidence for glucosamine and chondroitin becomes much weaker.
In other words, selecting a few positive studies can create a very different impression than looking at the full body of evidence. In addition, many supplements contain multiple ingredients such as green-lipped mussel, omega-3 fatty acids, hyaluronic acid, manganese, or plant extracts. If a dog improves while taking the supplement, it is difficult to know which ingredient is responsible.
Supplements are regulated differently from medicines. In most countries, supplements do not need to prove clinical effectiveness before being sold. Companies are usually required to demonstrate safety and product quality, but not necessarily that the product improves disease outcomes.
This does not mean every supplement is ineffective, but it does mean that marketing claims can sometimes sound stronger than the underlying evidence.
This is exactly why systematic reviews are so valuable. They step back from individual studies and examine the entire body of research, which often provides a more reliable picture of what truly works.
Other supplements
The review also looked at a wide range of other supplements (including turmeric, Boswellia and various herbal blends), but there was not enough consistent evidence to draw firm conclusions.
What this means for dogs with arthritis
The key takeaway is that while some supplements may have a role in arthritis management, not all ingredients are supported by the same level of scientific evidence. This highlights the importance of looking beyond marketing claims and focusing on treatments backed by good-quality research. Just because a supplement is popular doesn’t mean it works.
If your dog has arthritis, the most effective approach usually involves a combination of veterinary pain management, weight control, exercise and nutritional strategies tailored to your dog. Supplements can play a valuable role alongside these, but they should not replace them.
If you’d like help building the right plan for your dog, you can find more guidance here: