How to Choose the Best Fish Oil for Your Dog

Fish oil is one of the most popular supplements for dogs, and one of the most studied. The label can also be confusing. Some bottles list "1,000 mg fish oil" but contain far less of the omega-3s that do the work.

Here's what fish oil does, how to read a label, and how to pick and use a good one.

What Is Fish Oil and Why Do Dogs Get It?

Fish oil comes from the tissues of oily fish like sardines and anchovies. Its key ingredients are two long-chain omega-3 fatty acids:

• EPA (eicosapentaenoic acid), valued for its anti-inflammatory role

• DHA (docosahexaenoic acid), important for the brain, eyes, and nervous system

Plant oils like flaxseed contain a different omega-3 called ALA, but dogs convert ALA to EPA and DHA inefficiently, so fish oils are the better source.

What the Research Supports

• Arthritis: Omega-3s have the strongest research of any nutritional supplement for canine osteoarthritis. A large 2022 review found clear pain-relief benefit for omega-3 diets and supplements.

• Itchy, allergic skin: In a double-blind trial, dogs with atopic dermatitis improved on fish oil or flax oil for 10 weeks, while those on placebo did not. Vets generally find fatty acids helpful but only mildly effective on their own, so they work best alongside a treatment plan.

• Other conditions: Vets also use omega-3s alongside treatment for conditions like kidney disease, heart disease, and high blood lipids. These uses need veterinary guidance and dosing.

Fish oil isn't a cure or a way to prevent disease, and it works best as part of a plan with your vet.

Do Dogs Also Need Omega-6 and Omega-9?

Dogs need both omega-3 and omega-6 in balance. Omega-6 (linoleic acid) helps maintain the skin's moisture barrier, but many commercial diets already provide plenty. AAFCO caps the omega-6 to omega-3 ratio at 30:1 for dog foods, which in practice sets a minimum amount of omega-3.

Omega-9s are monounsaturated fats that a dog's body can make on its own, so they aren't "essential." They're a helpful extra in blended oils, but EPA and DHA are the main event.

How to Choose a Good Fish Oil for Your Dog

1. Check EPA and DHA in Milligrams

Ignore "1,000 mg fish oil" on the front of the bottle. Look for the combined EPA + DHA per serving, which is the number that matters for dosing. For skin support, choose an oil that provides plenty of EPA, and for joints, look for oils where EPA is well represented. EPA appears to be more effective than DHA for osteoarthritis.

2. Look for the Triglyceride Form

Fish oil comes as natural triglycerides or as processed ethyl esters. Triglycerides are generally considered better absorbed and more stable, though studies are mixed and mostly in humans, and the gap may shrink when taken with food. Products that specify the natural form are a good sign.

3. Make Sure It's Fresh

Omega-3s are fragile. Heat, light, and air turn them rancid, and oxidized oil can cause stomach upset and works against the benefits you want. Testing of consumer fish oils has found many exceeding recommended oxidation limits. Look for:

• Opaque bottles and a clear expiration date

• A stated shelf life and storage instructions

• No sharp, "fishy paint" smell

4. Check Purity and Sourcing

Fish from polluted waters can carry heavy metals and PCBs. Small fish like sardines and anchovies sit lower on the food chain, which helps limit contaminants. Look for brands that disclose where their fish comes from and share third-party test results for metals, PCBs, and oxidation.

5. Choose a Product Made for Pets

Pet-formulated oils are dosed for dogs and cats. Human supplements aren't necessarily unsafe, but many contain flavorings, sweeteners like xylitol (in gummies), or added vitamins A and D. Ask your vet before using a human product.

Why Choose Ultra Oil for Pets?

Ultra Skin & Coat is a blend of fish oil (sardine and anchovy), Canadian hempseed oil, flaxseed oil, and grapeseed oil. Here's how it stacks up against the checklist:

• Guaranteed EPA and DHA: 550 mg EPA and 276 mg DHA per teaspoon, about 826 mg combined.

• Sourcing: Ultra Oil is manufactured in the United States and uses wild-caught fish from a Peruvian fishery, using seine nets and other sustainable practices.

• Balanced blend: The guaranteed analysis lists at least 25% omega-3, 45.7% omega-6, and 14.9% omega-9, so it delivers all three in one product.

• Cold, virgin-pressed and human-grade: Made from non-GMO ingredients without fillers.

• Long shelf life: Up to 20 months. Store it in a cool, dry place or the refrigerator.

Because it's a blend, not a pure fish oil concentrate, the EPA and DHA come from its fish oil portion and the other oils bring their own fatty acids. That's why it's worth reading the EPA/DHA numbers rather than the marketing.

How Much Fish Oil Should You Give?

Dose by combined EPA + DHA, not total oil volume. Veterinary nutritionists commonly dose dogs at roughly 50 to 75 mg of EPA + DHA per kg of body weight for general support, with higher therapeutic doses (up to about 220 mg/kg) used under veterinary guidance, mostly for osteoarthritis. The National Research Council's safe upper limit is 2.8 grams of EPA + DHA per 1,000 calories of diet.

For Ultra Oil, mix one serving into your dog's food once a day based on weight:

For example, a 44-lb (20 kg) dog gets 1½ teaspoons, or about 1,240 mg of EPA + DHA, which is roughly 62 mg/kg. Give it with food to avoid stomach upset, and start with a smaller amount for a few days if your dog is new to fish oil. If your dog eats a skin, joint, or kidney diet that already contains EPA and DHA, tell your vet, because the total can add up.

Possible Side Effects and Precautions

Fish oil is generally well tolerated at appropriate doses. Watch for:

• Digestive upset: Loose stool, vomiting, or reduced appetite are the most common issues, especially with high doses or rapid changes.

• Weight gain: Fish oil is calorie-dense, so adjust meals if needed.

• Blood clotting and healing: Omega-3s can affect platelet function and wound healing at higher doses. Tell your vet before surgery, and if your dog takes NSAIDs or blood thinners.

• Fat-sensitive conditions: Dogs with a history of pancreatitis, high blood lipids, or other fat-intolerant conditions, and dogs with diabetes, should only have fish oil with veterinary approval. Fish oil hasn't been shown to cause pancreatitis, but extra fat can be a concern in at-risk dogs.

Stop and call your vet if your dog develops persistent vomiting, diarrhea, or lethargy.

Conclusion

A good fish oil delivers a clear amount of EPA and DHA, stays fresh, comes from a transparent source, and is dosed for your dog's size. Fish oil is a helpful supplement for skin, coat, and joint support, and it works best with your vet's guidance.