Omega-3 for Dogs: What It Does and How Much

Omega-3 for dogs comes in three forms: ALA from plants, and EPA and DHA from oily fish, krill and algae oil. Puppies need EPA and DHA while they grow, and AAFCO sets a minimum for them in puppy food.

For healthy adult dogs, AAFCO sets no minimum at all. If you add fish oil, a published safe upper limit tells you how much is too much.

That's the short version. The details below explain what these fats do, where the research is strong, where it's thin, and what to check before you open a bottle.

What are EPA and DHA?

Omega-3s are a family of fats. Three matter for dogs: ALA, EPA and DHA. The Merck Veterinary Manual names flaxseed oil as the best source of ALA, and oily fish, krill oil and algae oil as the best sources of EPA and DHA.

ALA is the plant form. In theory, a dog's body can build EPA and DHA from it. In practice, a review in the Journal of Veterinary Internal Medicine describes that conversion as "rather limited" in dogs.

Here's a striking example of what that means. In a Texas A&M study, mother dogs fed a diet rich in ALA produced milk rich in ALA, but not in DHA.

Their puppies did build up some DHA, more than puppies on a low omega-3 diet. They still built up less than puppies whose mothers ate DHA directly. So a plant oil and a fish oil are not interchangeable, even though both labels can say omega-3.

What does omega-3 do for a dog?

The strongest evidence is for puppies. Merck notes that ALA, EPA and DHA were added to the list of essential fatty acids for growth and reproduction in dogs.

AAFCO's nutrient profiles explain why. Its expert panel set minimums because the evidence shows these fats are needed for development of the nervous and visual systems before and after birth.

Puppy brains and eyes

Two studies show what that looks like. In the Texas A&M work, 12-week-old puppies with the most EPA and DHA in their diet had the strongest responses on retinal tests.

A 2012 study in JAVMA followed 48 Beagle puppies from weaning to one year. Those on a high-DHA food scored better on some learning, vision and movement tests than puppies on lower-DHA foods.

One honest caveat. That study was run by researchers at Hill's Pet Nutrition, and the high-DHA food also had more vitamin E, taurine, choline and L-carnitine. DHA can't take all the credit.

This is why growth foods carry DHA. Our guide on what to feed a puppy covers how to choose a complete puppy food.

Skin and coat

Coats are where omega-3 is marketed hardest, and the research in healthy dogs is thinner than the labels suggest.

Merck lists a dry, dull coat among the signs of an essential fatty acid shortfall. The essential fat every dog needs at every age, though, is linoleic acid, which is an omega-6.

In a 2023 University of Guelph study, 30 healthy dogs got one of three omega-3-rich plant oils for 16 weeks. Coat softness and shine scores rose in all three groups, with no difference between oils.

Every dog got an oil, so the study had no comparison with dogs given none.

Does my dog need an omega-3 supplement?

A healthy adult dog eating a complete and balanced food doesn't need one by any official standard. AAFCO lists EPA and DHA for adult maintenance as "not determined," because its panel found no scientific basis for an adult minimum.

Merck adds some useful context. Nutritional diseases are rarely seen in dogs fed a good-quality, complete and balanced commercial diet, or a homemade diet formulated by a board-certified veterinary nutritionist.

So a supplement is optional. If your vet suggests one for your dog, that's a different conversation, and they'll set the amount.

Food first, then extras

Omega-3 also shows up in foods and add-ons made for pets. Read those labels closely. Lenox and Bauer's review warns that some foods advertised as containing omega-3 get it from flaxseed or canola oil, which supply ALA.

If you want an everyday extra with the fish-type omegas in it, Choolip's Berry Good Milk is one option. It's a lactose-free cow's milk for cats and dogs that provides DHA and EPA, along with taurine, calcium and vitamins D3 and E.

It's a food, not a measured dose. Lactase handles milk sugar only, so skip it for a dog who reacts to dairy protein.

How much omega-3 is too much for a dog?

There is no official daily target for a healthy adult dog, but there is a ceiling.

The National Research Council set a safe upper limit for EPA and DHA combined, and Lenox and Bauer's review gives it as 370 mg per kilogram of body weight to the power of 0.75.

For a 10 kg dog, the review works that out at 2,080 mg.

That formula is hard to use in your head, so here it is worked out for a few sizes:

Dog's weight	Safe upper limit, EPA + DHA a day
11 lb (5 kg)	About 1,240 mg
22 lb (10 kg)	About 2,080 mg
44 lb (20 kg)	About 3,500 mg
66 lb (30 kg)	About 4,740 mg

Read these as a ceiling, never a goal. The limit covers EPA plus DHA from every source, including food, so add up the label figures rather than the total milligrams of oil.

Calories count too. The same review notes that one teaspoon of oil holds about 42 kcal, which adds up quickly for a small dog.

What should I know before starting fish oil?

Lenox and Bauer's review lists the possible downsides of omega-3 supplements, and it notes that problems, if they appear, are likely to be dose-dependent. The ones worth knowing:

• Digestive upset, including loose stools. The review suggests moving to a higher-fat diet slowly.
• Changes in how blood platelets work. Omega-3s and aspirin together have a combined effect on bleeding times.
• Slower wound healing. The authors suggest it may be wise to stop high doses before surgery.
• Rancidity. Fish oil can oxidize, and added vitamin E (alpha-tocopherol) helps keep it fresh.
• Too much of certain vitamins. High doses of oils such as cod liver oil raise a concern about vitamins A and D, though the authors rate that risk as low.
• Contaminants. Large amounts of fish or fish oil can raise exposure to mercury or PCBs.
• Weight gain, from the extra calories.

The review's point is that the amount matters. Tell your vet what your dog takes, especially alongside any medicine.

Call your vet promptly if your dog:

• has loose stools or an upset stomach that doesn't settle after starting a supplement
• is booked for surgery and takes high-dose fish oil
• takes aspirin or another daily medicine and you want to add omega-3
• gains weight after you add an oil

Questions dog parents ask

Can I give my dog fish oil made for people?

Ask your vet first. What counts is the EPA and DHA per serving, since that's what the upper limit measures. Check with your vet before using cod liver oil, because of the vitamin A and D concern.

Is salmon oil good for dogs?

Salmon is an oily fish, and Merck lists oily fish among the best sources of EPA and DHA. The same upper limit and cautions apply as for any fish oil.

Is flaxseed oil a good omega-3 for dogs?

It provides ALA, and dogs turn only a limited amount of ALA into EPA and DHA. If EPA and DHA are the goal, a fish, krill or algae source supplies them directly.

Do puppies need omega-3 supplements?

Not usually. A complete puppy food meeting AAFCO's growth profile already contains EPA and DHA. Check with your vet before adding more.

Do dogs need vitamins as well?

The ASPCA says a vitamin supplement is unnecessary on a complete and balanced diet unless a vet diagnoses a deficiency. Our guide to do dogs need vitamins explains when a vet might suggest one.

Sources

• Merck Veterinary Manual: Nutritional Requirements of Small Animals
• AAFCO: Proposed revisions to the AAFCO Dog and Cat Food Nutrient Profiles, Pet Food Committee, 2014
• Lenox CE, Bauer JE. Potential Adverse Effects of Omega-3 Fatty Acids in Dogs and Cats. Journal of Veterinary Internal Medicine, 2013
• Heinemann KM et al. Long-chain (n-3) polyunsaturated fatty acids are more efficient than alpha-linolenic acid in improving electroretinogram responses of puppies. Journal of Nutrition, 2005
• Zicker SC et al. Evaluation of cognitive learning, memory, psychomotor, immunologic, and retinal functions in healthy puppies fed foods fortified with DHA-rich fish oil. JAVMA, 2012
• ASPCA: Dog Nutrition Tips
• Richards TL et al. Effects of dietary camelina, flaxseed, and canola oil supplementation on coat quality in healthy adult dogs. Frontiers in Veterinary Science, 2023

This article is for general information and is not veterinary advice. Talk to your vet about your own dog — they know the animal in front of them.