Joint health: the omega-3 supplement guide
The omega-3 fatty acid supplementation is one of the most evidence-based nutritional interventions for the management of osteoarthritis in dogs and cats, and the omega-3 supplementation is also one of the most commonly misused. The owner who gives the omega-3 supplement in the wrong dose, the wrong form, or the wrong combination is the owner who is not getting the published benefit. The owner who gives the omega-3 supplement in the right dose, the right form, and the right combination is the owner who is getting the published benefit, and the published benefit is meaningful — a measurable reduction in the inflammation, a measurable improvement in the mobility, and (in many cases) a measurable reduction in the dose of the conventional pain medication (the NSAID, the gabapentin) that the pet requires.
This article is going to walk you through the practical guide to omega-3 supplementation for joint health in dogs and cats — the EPA and the DHA (the two relevant omega-3 fatty acids), the sources (the fish oil, the krill oil, the algae oil, the green-lipped mussel), the dose (the published therapeutic dose), the food vs supplement decision, the combination with other joint support (the glucosamine, the chondroitin, the MSM), the species-specific considerations, and the four mistakes that turn a useful intervention into an expensive placebo. I am a small-animal veterinarian with a focus on clinical nutrition, and the omega-3 supplementation is one of the most common interventions I recommend to my patients with osteoarthritis. The cases that go well share a common feature: the owner has understood the difference between the published therapeutic dose and the "label dose," has used the right source of the omega-3, has committed to the long-term supplementation, and has combined the omega-3 with the other evidence-based joint interventions. The cases that go poorly share a different common feature: the owner has used a low-dose commercial product, has not committed to the long-term supplementation, has not combined the omega-3 with the other interventions, and has concluded (incorrectly) that the omega-3 "does not work."
I want to be clear at the start: the omega-3 supplementation is not a replacement for the conventional arthritis management (the NSAIDs, the weight management, the physical therapy). The omega-3 supplementation is an adjunct — a useful adjunct, an evidence-based adjunct, but an adjunct. The owner who uses the omega-3 as a replacement for the conventional management is the owner whose pet is not receiving the conventional care. The owner who uses the omega-3 as an adjunct to the conventional management is the owner whose pet is receiving the full benefit.
What the omega-3 fatty acids are, and what they do
The omega-3 fatty acids are a family of polyunsaturated fatty acids (PUFAs) that are characterized by the location of the first double bond (the third carbon from the methyl end of the molecule). The relevant omega-3 fatty acids for the pet's joint health are:
Eicosapentaenoic acid (EPA). A long-chain omega-3 fatty acid (20 carbons, 5 double bonds) that is found primarily in marine oils (fish oil, krill oil) and in algae oil. The EPA is the omega-3 with the strongest anti-inflammatory effect in the joints, because the EPA is the precursor to the series-3 prostaglandins and the series-5 leukotrienes, which are the anti-inflammatory eicosanoids that compete with the series-2 prostaglandins and the series-4 leukotrienes (the pro-inflammatory eicosanoids that are produced from the omega-6 arachidonic acid).
Docosahexaenoic acid (DHA). A long-chain omega-3 fatty acid (22 carbons, 6 double bonds) that is also found primarily in marine oils and in algae oil. The DHA is the omega-3 with the strongest effect on the nervous system (the DHA is a major component of the brain and the retinal cell membranes), and the DHA has a secondary anti-inflammatory effect in the joints.
Alpha-linolenic acid (ALA). A short-chain omega-3 fatty acid (18 carbons, 3 double bonds) that is found in plant oils (flaxseed oil, chia seed oil, walnut oil). The ALA is converted to EPA and DHA in the body, but the conversion is inefficient in dogs and very inefficient in cats (cats have a particularly low activity of the desaturase enzymes that convert the ALA to the EPA and DHA). The ALA is, in practice, a poor source of the therapeutic EPA and DHA for the pet's joint health. The ALA is a useful supplement for the pet's general health, but the ALA is not a substitute for the EPA and DHA for the joint inflammation.
The mechanism of the joint benefit is the competition with the omega-6 arachidonic acid. The omega-6 and the omega-3 fatty acids compete for the same enzymes (the cyclooxygenases and the lipoxygenases), and the omega-3 fatty acids produce the less inflammatory eicosanoids than the omega-6. The dog or cat that has a high omega-6 to omega-3 ratio (the typical commercial pet food, which is rich in the omega-6 from the chicken fat, the corn oil, the vegetable oil) is the dog or cat that has a chronic inflammatory state. The supplementation with the EPA and DHA shifts the ratio toward the omega-3, and the shift reduces the inflammation.
The published evidence for the omega-3 supplementation in canine osteoarthritis is strong. A 2013 study in the Journal of the American Veterinary Medical Association (JAVMA) showed that the dogs with osteoarthritis that were supplemented with the omega-3 fatty acids showed a significant improvement in the weight-bearing (measured by the force plate), a significant reduction in the NSAID dose required, and a significant improvement in the owner-assessed mobility. The result is consistent with the previous studies on the omega-3 in the canine osteoarthritis, and the result is the foundation of the modern recommendation.
The sources of the omega-3
The right source of the EPA and DHA matters, and the source matters more than most owners realize.
Fish oil (the standard). The fish oil (typically from anchovies, sardines, mackerel, salmon) is the standard source of the EPA and DHA, and the fish oil is the source that is most commonly used in the published studies. The fish oil is available in liquid form, in capsule form, and in the form of the bottled "pet fish oil" products. The right fish oil is the fish oil that has been molecularly distilled to remove the heavy metals and the PCBs (the contaminants that are present in the unrefined fish oil), and the right fish oil is the fish oil that has been tested for the EPA and DHA content (not all fish oil products contain the labeled amount).
Krill oil (the premium). The krill oil is the oil from the Antarctic krill (Euphausia superba), and the krill oil is a premium source of the EPA and DHA. The krill oil contains the omega-3 in the phospholipid form (rather than the triglyceride form of the fish oil), and the phospholipid form is more bioavailable. The krill oil also contains the astaxanthin, a potent antioxidant that protects the omega-3 from oxidation. The krill oil is more expensive than the fish oil, and the krill oil is appropriate for the owner who is willing to pay the premium for the bioavailability advantage.
Algae oil (the vegan). The algae oil (from the microalgae Schizochytrium and similar species) is the vegan source of the EPA and DHA, and the algae oil is the right choice for the owner who prefers not to use the animal-derived supplements. The algae oil is also the right choice for the cat (the cat is an obligate carnivore, but the algae oil is a more sustainable source than the fish oil). The algae oil is comparable to the fish oil in the EPA and DHA content, and the algae oil is well-tolerated by most pets.
Green-lipped mussel (Perna canaliculus). A New Zealand shellfish that is a natural source of the EPA and DHA, plus a unique set of anti-inflammatory compounds (the glycosaminoglycans, the omega-3 fatty acids in the phospholipid form, the antioxidants). The green-lipped mussel is available in the freeze-dried form (as a powder, a capsule, or a treat), and the green-lipped mussel has been the subject of published studies showing a significant improvement in the canine osteoarthritis. The green-lipped mussel is more expensive than the fish oil, and the green-lipped mussel is appropriate for the owner who is willing to pay the premium for the unique anti-inflammatory compounds.
Cod liver oil (the historical). The cod liver oil is the historical source of the EPA and DHA, and the cod liver oil is still available. The cod liver oil also contains significant amounts of vitamins A and D, and the high vitamin content can produce toxicity in pets (especially cats) at the doses required for the joint benefit. The cod liver oil is not the right source for the pet's joint health, and the cod liver oil is not recommended for the regular use.
Flaxseed oil (the ALA). The flaxseed oil is the plant source of the ALA, and the flaxseed oil is a useful supplement for the general health. The flaxseed oil is not a substitute for the EPA and DHA for the joint inflammation, because the conversion of the ALA to the EPA and DHA is inefficient in dogs and very inefficient in cats. The flaxseed oil is appropriate as a general supplement, but the flaxseed oil is not the right source for the joint benefit.
The right source for the pet's joint health is the fish oil (the standard), the krill oil (the premium), the algae oil (the vegan), or the green-lipped mussel (the unique anti-inflammatory). The right source is the source that has been tested for the EPA and DHA content, and the right source is the source that is being given at the therapeutic dose.
The dose: the most important variable
The dose is the most important variable, and the dose is the most common source of error. The published therapeutic dose is:
- For dogs: 50–75 mg of combined EPA + DHA per kg of body weight per day. For a 25-lb dog, this is approximately 570–850 mg of EPA + DHA per day. For a 50-lb dog, this is approximately 1,140–1,700 mg of EPA + DHA per day.
- For cats: 30–50 mg of combined EPA + DHA per kg of body weight per day. For a 10-lb cat, this is approximately 135–230 mg of EPA + DHA per day. For a 15-lb cat, this is approximately 200–340 mg of EPA + DHA per day.
The dose that is on the label of the commercial "pet fish oil" products is often significantly lower than the published therapeutic dose. A 1000-mg fish oil capsule (the standard size) typically contains 300 mg of EPA + DHA (the rest is the other fish oil fatty acids). A 10-lb cat that is given one capsule per day is receiving 300 mg of EPA + DHA, which is at the upper end of the published dose for the cat, but is appropriate. A 50-lb dog that is given one capsule per day is receiving 300 mg of EPA + DHA, which is significantly below the published dose for the dog (the dog needs 1,140–1,700 mg, so the dog needs 4–6 capsules per day, not one). The owner who follows the label dose for the commercial product is the owner who is underdosing the pet.
The right dose is the published therapeutic dose, calculated based on the pet's weight, and the right dose is verified by the EPA + DHA content on the supplement label. The owner who is not calculating the dose based on the EPA + DHA content is the owner who is guessing, and the owner who is guessing is the owner who is underdosing.
The food vs supplement decision
Some commercial pet foods are fortified with the omega-3 fatty acids, and the fortified foods can provide a meaningful amount of the EPA and DHA. The fortified foods are typically the "joint support" or "skin and coat" diets, and the fortified foods contain the fish oil or the green-lipped mussel as a top-coating or as a kibble inclusion. The fortified foods are a convenient way to provide the omega-3, and the fortified foods are appropriate for the pet with mild joint disease or for the pet that does not tolerate the liquid fish oil or the capsules.
The downside of the fortified foods is the dose. The fortified foods typically provide 0.5–1.0% EPA + DHA on a dry-matter basis, which translates to a modest dose of the omega-3 per cup of food. The dog that is eating 2 cups of the fortified food per day is receiving approximately 200–400 mg of EPA + DHA per day, which is significantly below the published therapeutic dose for the dog. The fortified food is appropriate as a supplement to the regular supplementation, but the fortified food is not a substitute for the regular supplementation at the therapeutic dose.
The right approach is to use the supplement (the fish oil, the krill oil, the algae oil, or the green-lipped mussel) at the therapeutic dose, with the fortified food as a complementary support. The owner who is relying on the fortified food alone is the owner who is underdosing.
The combination with other joint support
The omega-3 supplementation is one component of the multi-modal joint management. The other components that should be combined with the omega-3:
Glucosamine and chondroitin. The two most common joint supplements, and the supplements that are the foundation of the joint cartilage support. The published evidence for the glucosamine and the chondroitin is mixed (the veterinary studies are less consistent than the omega-3 studies), but the clinical experience is that the glucosamine and the chondroitin are useful adjuncts, and the combination with the omega-3 is the standard. The dose for the glucosamine is 20–30 mg per kg per day for the dog, and the dose for the chondroitin is 15–30 mg per kg per day for the dog. The cat dose is similar, scaled to the body weight.
MSM (methylsulfonylmethane). A source of the organic sulfur, with some anti-inflammatory effects. The MSM is a useful adjunct, but the MSM is not the primary intervention. The dose is 50–100 mg per kg per day for the dog.
Adequan (polysulfated glycosaminoglycan, PSGAG). An injectable joint support medication, administered by the vet, that has a strong evidence base for the slowing of the cartilage degradation and the improvement of the joint function. The Adequan is not a supplement — the Adequan is a prescription medication — but the Adequan is one of the most effective joint interventions available.
Weight management. The single most important intervention for the overweight pet with osteoarthritis. The weight loss of 5–10% of body weight in the overweight pet produces a measurable improvement in the joint function, and the weight loss is the foundation of the joint management.
Physical therapy and the controlled exercise. The physical therapy (the range-of-motion exercises, the underwater treadmill, the swimming) and the controlled exercise (the leash walks, the swimming) are the interventions that maintain the muscle mass and the joint mobility, and the interventions are the foundation of the long-term joint health.
The omega-3 supplementation is the nutritional intervention that supports the joint health from the inside. The Adequan is the medical intervention. The weight management is the lifestyle intervention. The physical therapy is the physical intervention. The combination is the multi-modal approach, and the multi-modal approach is the approach that produces the best outcome.
The four mistakes that turn a useful intervention into an expensive placebo
Mistake 1: Underdosing the omega-3. The most common mistake. The owner follows the label dose on the commercial product, the label dose is significantly below the published therapeutic dose, and the pet is receiving an inadequate amount of the EPA and DHA. The fix is to calculate the dose based on the pet's weight and the published dose, and to verify the dose based on the EPA + DHA content on the supplement label.
Mistake 2: Using a low-quality or oxidized fish oil. The second most common mistake. The fish oil that is not molecularly distilled, that is not stored properly (the fish oil that is exposed to heat, light, or air), or that is past the expiration date is the fish oil that is oxidized, and the oxidized fish oil is not effective (and can be harmful, as the oxidized products are pro-inflammatory). The fix is to use a high-quality, molecularly distilled fish oil, to store the fish oil in the refrigerator, and to use the fish oil within the expiration date.
Mistake 3: Not committing to the long-term supplementation. The third mistake. The owner gives the omega-3 for a few weeks, the owner does not see an immediate improvement, the owner stops the supplementation. The omega-3 takes 4–8 weeks to produce the visible improvement (the omega-3 needs to be incorporated into the cell membranes, the omega-3 needs to shift the eicosanoid balance, and the omega-3 needs to reduce the chronic inflammation). The owner who stops the supplementation before the visible improvement is the owner who has not given the omega-3 a chance to work. The fix is to commit to at least 8 weeks of the supplementation, and to continue the supplementation indefinitely.
Mistake 4: Using the omega-3 as a replacement for the conventional management. The fourth mistake. The owner uses the omega-3 instead of the NSAID, instead of the weight management, instead of the physical therapy. The omega-3 is the adjunct, not the replacement. The fix is to use the omega-3 as part of the multi-modal approach, and to continue the conventional management alongside the omega-3.
The bottom line
The omega-3 supplementation is one of the most evidence-based nutritional interventions for the osteoarthritis in dogs and cats, and the omega-3 is a foundation of the multi-modal joint management. The right source is the fish oil (the standard), the krill oil (the premium), the algae oil (the vegan), or the green-lipped mussel (the unique). The right dose is the published therapeutic dose (50–75 mg/kg for dogs, 30–50 mg/kg for cats, of the combined EPA + DHA), calculated based on the pet's weight and the supplement's actual EPA + DHA content. The right combination is the omega-3 with the glucosamine, the chondroitin, the weight management, and the conventional management.
The owner who uses the omega-3 at the right dose, with the right source, with the right combination, and for the long term, is the owner who has a pet that has a measurable improvement in the joint function. The owner who uses the omega-3 at the wrong dose, with the wrong source, with the wrong combination, or for the wrong duration, is the owner who has a pet that does not improve. The difference is the right use. The right use is the framework above. The framework, applied with rigor, is the right prevention.
The pet with the well-managed osteoarthritis is a pet that has a good quality of life, that is mobile and active, and that is a source of joy for the owner. The pet with the poorly managed osteoarthritis is a pet that is in chronic pain, that is losing mobility, and that is losing the joy of the daily life. The difference is the management. The management is the framework above. The framework, applied with rigor, is the right prevention.
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About the author
Sarah Chen, DVM, is a small-animal veterinarian with a focused clinical interest in canine and feline clinical nutrition, with a particular interest in the nutritional management of osteoarthritis, the evidence base for joint supplements, and the practical integration of nutritional interventions with conventional medical management. She works in general practice in the Pacific Northwest and writes regularly on the practical intersections of food, disease management, and owner compliance.
