We often hear that it's enough to "give omega-3s" to your dog.

In reality, it's much more complex. The term omega-3 encompasses several fatty acids with very different properties. Depending on their origin, metabolism, and composition, they do not have the same benefits, especially in osteoarthritis.

Veterinary literature is quite clear: the observed benefits mainly concern marine omega-3s rich in EPA and DHA. Conversely, the mere presence of the "omega-3" label on packaging absolutely does not guarantee efficacy for joints.

What are the different omega-3s?

In dogs, there are mainly three distinct fatty acids.

ALA

Alpha-linolenic acid (ALA) is found in certain vegetable oils, such as flaxseed or chia.

Dogs can convert a small portion of it into EPA and DHA, but this conversion remains limited. Studies show that ALA intake alone does not achieve the same concentrations as direct EPA and DHA intake.

In other words, ALA is not equivalent to marine omega-3s.

EPA and DHA

EPA and DHA are primarily supplied by fish oils and certain algal oils.

These two molecules have been the most studied in dogs with osteoarthritis. They are associated with anti-inflammatory effects and a moderate improvement in some clinical signs.

The first key takeaway is simple: not all omega-3s are equal. Without knowing the source and quantity of EPA and DHA, the mention "rich in omega-3" ultimately provides little information.

How do they work?

EPA and DHA are progressively incorporated into cell membranes.

They then modify the production of certain molecules involved in inflammation and promote the synthesis of mediators that contribute to its resolution.

Unlike conventional anti-inflammatory drugs, they do not directly block inflammation.

Their action is more gradual: they modify the body's functioning over weeks, which explains why their effect takes longer to appear.

What do studies actually say?

The most comprehensive reference is the meta-analysis by Barbeau-Grégoire et al. (2022), which analyzed 72 clinical trials on nutraceuticals and enriched foods in osteoarthritic dogs and cats.

Its conclusion is rather encouraging: EPA and DHA are among the dietary supplements with the strongest evidence of efficacy against osteoarthritis-related pain, ahead of glucosamine and chondroitin.

Several trials support this finding.

• Roush et al. (2010) observed an improvement in limb weight-bearing in dogs fed a fish oil-enriched diet.
• A second study by Roush et al. showed an increase in blood omega-3 concentrations, accompanied by clinical improvement in some dogs followed in veterinary practice.
• Mehler et al. (2016) reported an improvement in clinical signs of osteoarthritis after daily EPA and DHA supplementation.
• Fritsch et al. (2010) confirmed that increased intake led to higher EPA and DHA concentrations in the body, although the clinical benefit remained moderate.

In summary, the scientific evidence is quite robust: EPA and DHA can improve some symptoms of osteoarthritis, but their effect remains gradual and moderate. They do not replace pain medication when a dog is in severe pain.

What dosage is used in studies?

There is no universal dose valid for all dogs and all supplements.

However, several studies provide a general order of magnitude.

The study by Mehler et al. used approximately 69 mg/kg/day of EPA + DHA, with an EPA:DHA ratio of 3:2.

Other research indicates that an intake between 50 and 100 mg/kg/day of EPA + DHA generally corresponds to the doses studied for osteoarthritis.

However, increasing doses does not automatically lead to better results. Beyond a certain threshold, the clinical benefit appears to plateau.

The actual amount provided mainly depends on the product's concentration of EPA and DHA, not on the number of capsules or milliliters administered.

Not all sources are equal

Vegetable oils: useful, but not equivalent

Flaxseed, chia, or hemp oils mainly provide ALA.

Even if dogs can convert a small part of this ALA into EPA and DHA, this conversion is insufficient to achieve the same concentrations as with a marine source.

For joint health, the studies are clear:

ALA alone ≠ EPA + DHA.

Fish oil

The vast majority of studies conducted in osteoarthritic dogs use fish oil.

It is currently the best-documented source of EPA and DHA in veterinary literature.

Algal oil

Certain algal oils directly provide DHA and sometimes EPA.

Studies show that they do increase blood concentrations of these fatty acids in dogs.

However, there are fewer clinical trials on osteoarthritis compared to fish oil. Nevertheless, they remain a credible alternative when they genuinely provide EPA and DHA.

Is the chemical form important?

It is often said that certain forms are much better absorbed than others.

Differences in bioavailability do exist, especially in human literature. However, in osteoarthritic dogs, the data remains insufficient to claim that one form is systematically superior to all others.

What matters most is:

• the actual amount of EPA and DHA;
• manufacturing quality;
• product stability.

Marketing pitfalls

The same arguments often reappear.

The first consists of highlighting the presence of "omega-3s" without specifying which ones. Yet, for joints, it is primarily EPA and DHA that concern us.

The second is to display only the total omega-3s. This figure can be high while consisting primarily of ALA, which is much less documented in osteoarthritis.

Another common shortcut: leading people to believe that a natural product is necessarily risk-free.

Omega-3s have a good safety profile, but this does not mean they can be given without careful consideration, especially to a sick dog, one undergoing treatment, or before surgery.

Finally, an essential point is often overlooked: oxidation.

EPA and DHA are fragile. Oil that is poorly stored, exposed to heat, light, or air, gradually loses quality.

Packaging, storage conditions, and adherence to the use-by date after opening are therefore far from minor details.

For which dogs?

Omega-3s rich in EPA and DHA can be suitable for dogs suffering from mild to moderate osteoarthritis, or as a complement to a more comprehensive management approach.

They are generally integrated into a multimodal approach that may combine:

• weight control;
• appropriate physical activity;
• rehabilitation;
• pain treatments when necessary.

However, patience is required. Effects are generally not visible for several weeks.

EPA and DHA are also being studied in other areas, particularly in veterinary dermatology, nephrology, and cardiology. However, this does not mean they are effective against all diseases.

In the most painful forms of osteoarthritis, they never replace appropriate veterinary care. They are a supplement, not a treatment on their own.

Precautions for use

Studies show that omega-3s are generally well tolerated.

Reported side effects are primarily digestive and usually remain moderate.

However, particular vigilance is recommended for dogs:

• receiving anticoagulant treatment;
• with a bleeding disorder;
• scheduled for surgery.

At commonly used doses, complications appear rare, but it is still advisable to discuss it with your veterinarian before starting supplementation.

Product quality is also important. Rancid or oxidized oil no longer has the same properties as that used in studies.

Therefore, store supplements according to the manufacturer's recommendations, away from heat, light, and air.

Conclusion

Available scientific data are rather reassuring: marine omega-3s rich in EPA and DHA are among the best-documented dietary supplements for canine osteoarthritis.

However, it is important not to confuse everything. Not all omega-3s are equivalent, and a product simply labeled "rich in omega-3" will not necessarily provide the quantities of EPA and DHA studied in dogs.

Finally, even if their benefit is real, omega-3s do not replace a veterinary diagnosis or pain treatment when necessary. They are part of a comprehensive management plan tailored to each dog.

Sources 

1. Barbeau-Grégoire M. et al. (2022). A Systematic Review and Meta-Analysis of Enriched Therapeutic Diets and Nutraceuticals in Canine and Feline Osteoarthritis. International Journal of Molecular Sciences. 

2. Mehler S.J. et al. (2016). A prospective, randomized, double blind, placebo-controlled evaluation of the effects of eicosapentaenoic acid and docosahexaenoic acid on the clinical signs and erythrocyte membrane polyunsaturated fatty acid concentrations in dogs with osteoarthritis. 

3. Roush J.K. et al. (2010). Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis. 

4. Roush J.K. et al. (2010). Multicenter veterinary practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs. 

5. Fritsch D.A. et al. (2010). Dose-titration effects of fish oil in osteoarthritic dogs. 

6. Dahms I. et al. (2019). Safety of a novel feed ingredient, Algal Oil containing EPA and DHA, in a gestation-lactation-growth feeding study in Beagle dogs. 

7. Dominguez T.E. et al. (2020). Study comparing vegetable source rich in ALA and marine source rich in EPA/DHA in dogs. 

8. Burron S. et al. (2024). The balance of n-6 and n-3 fatty acids in canine, feline, and equine nutrition: exploring sources and the significance of alpha-linolenic acid.