Omega fatty acids for dogs and cats

A comprehensive look at Omega fatty acid sources for canine and feline patients, and the pros and cons of each.

Omega fatty acids are vital for health in our animal patients. The most-studied Omega-3s are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both EPA and DHA have strong antioxidant and anti-inflammatory properties; cell membranes also need DHA to stay sufficiently fluid for optimal function. This article looks at the main sources of Omega-3s on the market, from the bottom of the food chain, and the pros and cons of each when it comes to dogs and cats.

Algal oil

Oil made from certain species of algae has a high DHA content. But natural algae contain little to no EPA. To achieve a better EPA content, certain species have been genetically selected for this ability. But the ratio of DHA to EPA is still upside down compared to most OMEGA-3 supplements; there is more DHA than the stronger anti-inflammatory EPA. While algal oil is a valid choice for vegan humans, dogs and cats are best served by getting their Omega-3s from an animal source.


A relative newcomer to the Omega scene, phytoplankton forms the basis of the marine food ecosystem. A whole food supplement, it offers a beneficial array of vitamins, minerals, amino acids and fatty acids, including EPA. Freshwater phytoplankton does not produce EPA. A proprietary combination of freshwater and marine phytoplankton does, but in only miniscule amounts. Neither is a sufficient source of Omega-3s.

Flaxseed/nut/vegetable oils

Plant oils contain several fat types. Coconut and palm oil are high in saturated fat. Most other common cooking oils, like corn, sunflower and safflower oils, are more unsaturated. They contain mostly Omega-6. Flaxseeds and a few other seeds and nuts also contain the Omega-3 ALA, which has beneficial effects of its own, particularly on skin and coat health.

Coconut oil

Many people are confused about this product, but there are no Omega fats in coconut oil. It is almost entirely saturated fat, with very small amounts of oleic and linoleic acids.

Krill oil

Krill oil is a popular non-fish Omega-3 alternative that is heavily promoted by some of its sellers. Krill are tiny, pinkish shrimp-like crustaceans that are said to comprise the largest biomass on earth. They are a keystone species, and a major food source for multiple species of fish, whales, seals, squid and birds. Krill are harvested for many purposes, but increasingly for Omega-3 oil supplements.

However, even though there are lots of krill in the ocean, warming temperatures and decreasing sea ice pose a dire threat to them. Krill feed on phytoplankton under the sea ice, so less ice means fewer krill. Moreover, krill are often harvested in and around critical feeding grounds for the animals that eat them. These factors are already causing krill depletion in local areas, threatening dozens of species of fish, seabirds and mammals, including whales. Populations of Chinstrap and Adélie penguins in Antarctica have been declining since the 1980s due to the decimated krill population, and that trend is accelerating.

Greenlip mussel oil

New Zealand greenlip mussels (Perna canaliculus, GLM) are grown in the Marlborough Sound under a Sustainable Farming Program. This ensures the long-term viability of the greenlip mussel industry, with minimum impact on the environment. GLM are bivalve mollusks that provide a rich source of 33 fatty acids, including all 18 known forms of Omega-3s (including EPA, DHA and ALA).

Among the GLM’s unique array of Omegas is ETA (eicosatetraenoic acid). ETA — which is not found anywhere else to any measurable degree — has extremely powerful anti-inflammatory properties. GLM oil has less saturated fat and more mono- and polyunsaturated fat, than fish or cod liver oils. When cold-pressed and packaged at the source, GLM oil appears to be more bioavailable than fish oil, so a smaller amount can be used to get the same benefits.

MOXXOR is a good source of greenlip mussels (using the coupon code DRJEAN will get you a good discount).

Calamari oil

This is another new kid on the block. Calamari is a marine animal, and a close relative of the clever octopus. They are abundant, and their population is growing. Like algae, calamari are much higher in DHA than EPA. As the more powerful anti-inflammatory, EPA is probably more suited to most dogs than DHA, which is important primarily during fetal development, and again later as the aging brain starts to decline.

Squid live in a variety of water temperatures and conditions. Cold water dwellers have much more Omega fatty acids than those in warmer waters, where the temperature allows for more fluid membranes. Therefore squid from northern and extreme southern waters are likely more beneficial. There is always the potential for over-harvesting, but at this time the population is robust.

Fish-based oils

Fish body oil and cod liver oil are the most common sources of EPA and DHA. Small fish get it from eating algae, plankton and aquatic plants; predatory fish eat small fish and accumulate it. The advantage of fish oil is that species at the top of the food chain have a higher concentration, so it takes less fish oil to get the same quantity of Omega-3.

Most salmon oil (especially from Canada and the Atlantic Ocean, Scotland and Norway) comes from farm-raised salmon. These factory-farmed fish are grown in polluted, overcrowded pens; they are heavily vaccinated, are fed dyes, antifungals, parasiticides and antibiotics, and contain up to ten times more mercury, dioxins, PCBs and other toxins than wild fish. Farmed salmon also pose a serious threat to wild species in both Atlantic and Pacific oceans due to the interbreeding of escaped fish, parasites and infectious diseases.

Farmed salmon are extremely fatty due to their diet and lack of free movement. Oil from farmed fish contains about the same amount of Omega-3s as wild fish — but far more Omega-6s, thanks to the unnatural corn, soy and trash fish they are fed.

Even salmon labeled “Alaska”, “wild” or “wild-caught” may not be truly wild. About a third of both Pacific and Atlantic salmon are bred and raised in hatcheries. Their release into the ocean is threatening both wild salmon and other fish.

Cod liver oil is a good choice when properly produced. But cod liver oil for humans is commonly supplemented with vitamins A and D at levels that could easily become toxic in cats and dogs. Moreover, a loophole in the law allows non-cod species to be labeled as cod.

Inexpensive mass-produced fish oils usually contain filler oils (such as sunflower, safflower, canola and olive oil), which add undesirable Omega-6s. They may also be processed with harsh chemicals because of cost considerations.

It may make sense to stay away from top-level predatory fish to avoid the pollutants that accumulate in their fat. Menhaden is the source of most “fish oil” not identified by species. Unfortunately, it is also a threatened keystone species. Sardine, herring and anchovy oils are more sustainable and cleaner than most other fish oils.

While a product made specifically for pets may not have the additives found in human products, many are quite low in potency, and may not be sufficient for your patients’ needs.

Processing is the final wild card in the game. Make sure the fish oil products you choose are safely extracted without high heat or solvents, and are tested by an independent laboratory for PCBs, mercury and other pollutants.

One company I recommend for quality fish oil is Nordic Naturals.

Requirements for dogs and cats

Adult dogs and cats require linoleic acid (LA, an Omega-6), and alpha linolenic acid (ALA, an Omega-3) in their diets. Cats also need arachidonic acid, an Omega-6. Both EPA and DHA are considered essential for young puppies and kittens.

It’s not that adult dogs and cats don’t also need EPA and DHA for good health. It’s just that the National Research Council, upon whose work the AAFCO pet food nutritional standards are based, couldn’t agree on a necessary minimum level, so they just left them out of the recommendations.

Still, we know that providing these nutrients provides many health benefits, so it’s wise to supplement them to animal patients.

Omega-3s – plant or animal?

Perhaps the most common point of confusion about Omega-3s is the difference between plant and animal sources. Many plants are a good source of LA; some, like flaxseed, hemp, walnuts, canola and soybeans also contain ALA. Hemp also contains gamma-linoleic acid (GLA), an anti-inflammatory Omega-6.

It’s important to know that adult dogs and cats can’t readily convert ALA into EPA and DHA. Very young puppies can manufacture DHA, but they lose that ability at weaning. At best, dogs can convert only 1% to 2% of ALA to EPA, and they convert virtually no ALA to DHA. Cats are even more limited.

When recommending Omega-3 oils for canine and feline patients, it’s important to be aware of your sources, and to do some research to ensure you’re suggesting the healthiest possible choices.


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Hinke JT, Cossio AM, Goebel, et al. “Identifying Risk: Concurrent Overlap of the Antarctic Krill Fishery with Krill-Dependent Predators in the Scotia Sea”. PLoS One. 2017; 12(1): e0170132.

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Rule DC, Broughton KS, Shellito SM, Maiorano G. “Comparison of muscle fatty acid profiles and cholesterol concentrations of bison, beef cattle, elk, and chicken”. J Anim Sci. 2002 May;80(5):1202-11.


Dr. Jean Hofve earned her Doctor of Veterinary Medicine at Colorado State University. In addition to conventional veterinary training, she studied veterinary homeopathy, homotoxicology, Reiki, and other holistic modalities. She has researched pet food and feline nutrition for more than two decades, and is an expert on holistic pet health and the commercial pet food industry. She is an official advisor to AAFCO, the organization that sets pet food rules and standards in the U.S. and Canada. Dr. Hofve co-authored the books Holistic Cat Care and Paleo Dog.