Dogs’ Digest: joints – can dietary supplements help?

Joint conditions in dogs are increasingly reported in the UK.

A study of dogs within a veterinary programme (Vet Compass) found just less than 70% of dogs had OA, which they equated to around 200,000 dogs affected in the UK (Anderson et al, 2018).

OA can develop at any time, but is more common in senior dogs. Size is a factor – large and giant breeds are over-represented, as are some specific breed groups, including working, gundog and pastoral breeds. Bodyweight is also important; overweight dogs will have increased loading on their joints, which can raise the likelihood of developing the condition (Mele, 2007).

OA in dogs is often secondary to a specific underlying cause seen earlier in life. Developmental conditions – such as dysplasia, ligament rupture or traumas involving broken bones – lead to an increase in catabolic metabolism, with both cartilage and bone destruction, as well as a painful inflammatory response.

Many ways exist to support dogs that have, or are at risk of developing, OA. Some methods are well known, while others are just emerging and require more research to identify benefits. Weight reduction is a simple, effective treatment in the early stages. Marshall et al (2010) found weight loss between 6% to 9% of bodyweight significantly decreased lameness in dogs when assessed by visual scales and kinetic gait analysis.

Glucosamine and chondroitin

Glucosamine and chondroitin sulfate are two of the most significant components of cartilage naturally produced inside the body. Glucosamine is a building block used to synthesise the larger proteoglycans needed to enhance the water content in the cartilage (which impacts the elasticity and resistance of the joints, and general lubrication of the joint system).

Chondroitin is a natural glycosaminoglycan, a key part of proteoglycan complexes within the cartilage, with a defined structural role to maintain cartilage elasticity and hydration, and provide resistance to compression.

Studies show mixed results for supplementation. While some show none or limited effect, in others, a combination of glucosamine and chondroitin sulfate has been found to modify cartilage metabolism and improve joint pain (McCarthy et al, 2006; Gupta et al, 2012). Issues around study design, impartiality and supplement quality are thought to be the reason for mixed results (Bhathal et al, 2017).

Omega 3

Omega 3 fats have been well-researched, and some compelling evidence exists that supplementation with fatty acids (eicosapentaenoic acid and docosahexaenoic acid) can slow and reduce both the degradative and the inflammatory processes associated with arthritis. A 2016 study found 50% of dogs with symptoms of OA showed signs of improvements in pain and joint movement when given fish oils (Mehler et al, 2016).

Curcumin

Of the emerging aids coming forward – curcumin, the key constituent of turmeric – looks interesting, and is thought it may help decrease joint-related inflammation and pain.

A 2003 study with dogs found no beneficial effect, but when combined with hydrolysed collagen and green tea, pain and stiffness were reduced (Innes et al, 2003; Comblain et al, 2017). With these mixed supplement studies it is harder to identify which supplement is beneficial, so more work is needed to identify the key active ingredients.

Hyaluronic acid

Hyaluronic acid is a glycosaminoglycan, like chondroitin, which is found in cartilage and may be supplemented through the diet or in an injected form. To date, no canine studies exist on the dietary form to indicate efficacy, but studies using the injected form have shown significant improvement in joint movement and decreased lameness (Lee et al, 2019).

Coconut oil

Coconut oil is one of the latest supplements being considered for OA. It’s a source of medium-chain triglycerides (MCTs), which may help reverse ligament damage, and aid with inflammation and joint pain. While some scientific evidence exists of the MCT effect in other areas (cognitive function, epilepsy), no definitive OA study has been published (Pan, 2010; Berk, 2019; Hall and Jewell, 2012).

In addition, questions exist around calorific density, product quality and refinement methods, making it difficult to see a potential benefit of supplementing coconut oil, yet.