Fish Oil for Dogs: Benefits, Dosage and Best Types

By Tailwisp Editorial TeamUpdated October 17, 20263 min read

Fish oil is one of the most commonly recommended supplements for dogs. Many owners notice a shinier coat, and vets use it as part of treatment for several conditions. But dose and quality matter, and it is not a cure-all.

What fish oil contains

Fish oil is rich in two long-chain omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These fats are incorporated into cell membranes and influence inflammation. Dogs cannot convert plant omega-3s such as ALA from flaxseed efficiently into EPA and DHA, so marine sources are more direct. See fat and omega fatty acids.

Potential benefits

• Skin and coat. Omega-3s may reduce inflammation in itchy, allergic skin and improve coat quality. See skin allergies in dogs.
• Joints. There is reasonable evidence that omega-3s help dogs with osteoarthritis. See arthritis in dogs and glucosamine for dogs.
• Heart. May help some dogs with heart disease, under veterinary supervision.
• Kidney. Some veterinary diets for kidney disease include omega-3s.
• Brain and eyes. DHA is important for development in puppies and may support brain health in older dogs.

Evidence varies by condition, and results in individual dogs differ.

Choosing a product

• Look for EPA and DHA amounts on the label, not just total fish oil.
• Choose reputable brands that test for purity, heavy metals and oxidation, and ideally have third-party certification.
• Check the source, such as anchovy, sardine, salmon or algae oil.
• Avoid products with additives such as xylitol or flavorings that may be harmful. See xylitol.
• Avoid cod liver oil in routine use, because it contains vitamins A and D that can build up. See essential vitamins.

Dosage

There is no single dose. Recommended amounts vary with the condition being treated, the product's EPA and DHA content and your dog's weight. Veterinary guidelines often use total EPA plus DHA per kilogram of body weight, with higher doses for joint problems than for general health. Ask your vet to calculate a dose, and follow product instructions. Start low and increase gradually.

Side effects

• Fishy breath and burps
• Loose stools or diarrhea
• Vomiting
• Weight gain, since oil is calorie-dense
• Delayed wound healing and reduced clotting at high doses
• Pancreatitis risk in susceptible dogs

Stop and call your vet if side effects appear.

Safety tips

• Inform your vet before surgery, because high doses may affect clotting.
• Count the calories.
• Store properly, in a cool, dark place, and often in the refrigerator, to prevent rancidity. Discard oil that smells strongly rancid.
• Do not give human supplements without checking ingredients.

Natural sources

Feeding oily fish, such as sardines in water, provides omega-3s, but doses are less predictable. See salmon for dogs.

Fish oil versus other omega-3 sources

Krill oil, algae oil and green-lipped mussel are alternative sources of omega-3s. Each has different concentrations of EPA and DHA, and evidence varies. Algae oil is suitable for dogs allergic to fish, and for those following a plant-based diet. Whatever you choose, look at the EPA and DHA content, and ask your vet to compare products.

When to see a vet first

If your dog is itching, limping or losing weight, supplements should not delay diagnosis. Fish oil can complement treatment, but it does not replace it. Always tell your vet which supplements your dog takes, since some combinations of medications and supplements can affect bleeding, blood sugar or blood pressure.

The takeaway

Fish oil can help some dogs, especially with skin and joint problems. Choose a quality product, use the right dose and work with your vet.

This article is general educational information, not veterinary advice. Every dog is different. If your dog is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.