Cod liver oil for dogs

By the PetFishOilGuide editorial team · Updated October 13, 2026 · How we compare

As an Amazon Associate I earn from qualifying purchases. Links to Amazon on this page are affiliate links.

Cod liver oil gives a dog some EPA and DHA, but it also carries vitamins A and D. Both can build up and cause illness when given over weeks or months. We have found no veterinary source with a safe amount for dogs. Read the label for vitamin A and D, and ask your vet before using it.

Cod liver oil is an old household product, and owners ask whether it works like fish oil. It overlaps with fish oil but is not the same thing. This page explains the difference, the risk, and how to read a label. It is not veterinary advice, and this page has not been checked by a veterinarian.

Liver oil versus body oil

Cod liver oil is pressed or extracted from the liver of cod. The fish oil in most omega-3 supplements for dogs comes from the bodies of fish such as salmon, sardines or anchovies. The liver stores fat-soluble vitamins, so cod liver oil usually contains vitamin A and vitamin D along with some EPA and DHA. The amount of each differs by brand, so the label is the only reliable guide.

Why vitamin A and D matter for dogs

Dogs need both vitamins. Both are fat-soluble, meaning the body can store them, so a little extra every day can add up.

Vitamin A. VCA Animal Hospitals says vitamin A poisoning most commonly follows feeding raw liver, cod liver oil, or other vitamin A-rich supplements over several weeks to months. Signs it lists for chronic cases include a poor coat, dry skin, weakness, weight loss, constipation, excessive bone development, and painful or limited movement. VCA also says the extra bone growth is not reversible, though comfort may improve after the intake stops. The Merck Veterinary Manual describes dogs as less sensitive to excess vitamin A than cats, and lists skeletal malformation, spontaneous fractures and internal bleeding as common signs of toxicity. We did not find a numeric safe upper limit for vitamin A on a page we could check, so we give none.

Vitamin D. The FDA says dogs can be poisoned by too much vitamin D from pet food, from a household member's vitamin D supplements, or from rodenticides. Signs include vomiting, poor appetite, increased drinking and urination, drooling, and weight loss, and in severe cases kidney failure. In 2018 and 2019 the FDA warned about dog foods with too much vitamin D. The expanded Hill's recall covered 86 lots of 33 varieties of canned dog food. Those were food manufacturing errors, not cod liver oil, but they show that the margin is real. Diet-related toxicity usually develops gradually, while supplement or rodenticide poisoning can show up in hours or days.

For a number, a 2023 paper by Jewell and Panickar reports that AAFCO sets the safe upper limit for vitamin D in adult-maintenance dog food at 3,000 IU per kg of dry matter, lowered from 5,000 in 2016 (Frontiers in Veterinary Science, 2023). That limit is for a whole diet, not a supplement, and the NRC's figure differs slightly, so do not use it as a supplement dose. It only shows that the allowed range for food is narrow and that your dog's food already contains vitamin D.

How to read a cod liver oil label

Look for three things per serving, and check what the serving is (a teaspoon, a pump, a capsule).

1. EPA and DHA in milligrams. Dosing guidance is written in combined EPA+DHA, not in "cod liver oil" or "omega-3." A label that gives only the total oil cannot be used for dog math. See EPA+DHA versus fish oil on the label.
2. Vitamin A, with its unit. It may be in IU, in mcg RAE, or as retinol. Do not compare numbers in different units.
3. Vitamin D, with its unit. The same rule applies.

Here is an example with a made-up label, not a real product. A teaspoon lists 150 mg EPA, 100 mg DHA, 2,500 IU vitamin A and 250 IU vitamin D, so 250 mg EPA+DHA. A 50 lb dog (22.7 kg) has a published range of 1,134 to 1,701 mg of EPA+DHA per day (50 and 75 mg per kg, from Lenox, Today's Veterinary Practice, 2016). Dividing 1,134 by 250 gives 4.5 teaspoons, and at that amount the vitamins come to 11,340 IU of A and 1,134 IU of D. That is arithmetic, not a recommendation. It shows why a product low in EPA+DHA and high in vitamins can stack vitamins long before it reaches an omega-3 target. Add up the vitamins your dog gets from food, multivitamins and other supplements too.

Cod liver oil compared with fish or salmon oil

A fish body oil or salmon oil is usually sold for its EPA and DHA, and the label should say how much. Cod liver oil is also sold for its vitamins. We have no source that compares them in dogs, so we do not claim one is better. Because dosing guidance is built on EPA+DHA, a product that lists those clearly and does not add vitamins is easier to use with that guidance. Our fish oil vs salmon oil page compares those two, and our table sorts products by the EPA+DHA printed on the label. If you are thinking about a human product, read human fish oil for dogs.

When to call your vet

Ask your vet before starting cod liver oil, and always tell them if your dog already takes a multivitamin or eats liver. Call your vet if your dog has vomiting, poor appetite, more drinking and urinating than usual, stiffness or pain moving, or a dry, poor coat while on a vitamin-containing supplement. Call right away if you think your dog swallowed a whole bottle. The ASPCA Poison Control line is (888) 426-4435 and the Pet Poison Helpline is 1-800-213-6680. A consultation fee may apply. See also fish oil side effects in dogs and omega-3 for dogs.