In the pet supplement market, fish oil for dogs stands out as one of the few products with evidence to back up the enthusiasm.

Fish oil has been shown to benefit dogs with arthritis, skin problems (including allergies), heart conditions, and kidney disease. It also supports brain development in puppies and enhances cognition in aging dogs and seniors.

Honest Paws and Nordic Naturals offer the best fish oils for dogs for sourcing, price, and independent certification.

Choosing the best fish oil for dogs can be tricky. It requires careful consideration of four main factors: transparent EPA/DHA disclosure, third-party certification, triglyceride form, and sustainable sourcing.

In this article, we will dive deeper into the scientifically proven benefits of fish oil for dogs and discuss its dosage, side effects, and buying tips.

Is Fish Oil Good for Dogs?

Yes, fish oil is good for dogs. Fish oil provides polyunsaturated essential omega-3 fatty acids, such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).

Polyunsaturated means they are the good type of fats (you have probably heard that there are two types of fats - good and bad). Essentially, this means the dog's body cannot make them on its own and needs to get them through food or supplements.

But what exactly do omega-3 fatty acids do for dogs? Omegas can help with osteoarthritis and joint pain, skin and coat problems, support a healthy heart and kidneys, and enhance cognition.

A randomized, double-blind, controlled clinical trial found that osteoarthritic dogs fed a fish-oil omega-3 diet improved from a median lameness grade 4 to grade 1 by day 84, while placebo dogs stayed at grade 4-5.

In another study, 82% of OA dogs on the fish-oil test food had improved weight bearing. Their mean peak vertical force rose to 5.6% vs 0.4% in the dogs on the control food. It took between 6 and 12 weeks for the effects to kick in.

A recent 2025 study reports that "omega-3 supplementation can reduce pruritus by up to 65% after four weeks of use, in addition to reducing the incidence of secondary complications, such as pyoderma and excoriation," in dogs with atopic dermatitis.

Fish oil supplementation can help reduce inflammation and cachexia (muscle wasting) in dogs with chronic heart disease, according to a study published in 2008 in the Journal of Veterinary Internal Medicine.

Studies have shown that omega-3 fatty acids have renoprotective properties, meaning they can help protect kidney tissue and function in dogs with early-stage renal insufficiency.

Omega-3 fatty acids promote cognition. DHA-rich fish oil improves cognitive function in young puppies, a study confirms. Another study reports cognitive enhancement in older dogs given fish oil supplements.

How Much Fish Oil Should I Give My Dog Per Day?

You should give your dog between 50 and 220 mg of EPA + DHA per kilogram of body weight, which equals 22.6 to 99.8 mg per pound.

The published therapeutic dose range for EPA+DHA in dogs is 50 to 220 mg/kg, according to the dosing framework published by Today's Veterinary Practice.

The exact dose depends on the dog's overall health and the underlying reason for using fish oil supplements.

For example, lower doses (50 mg/kg) are used for inflammatory, renal, and cardiac conditions. Doses at the higher end of the range are typically recommended for dogs with osteoarthritis.

No official consensus exists on EPA + DHA dosing for pets. Veterinarians and the National Research Council (NRC), a highly credible organization dedicated to applying scientific research in practice, follow the 50 to 220 mg/kg guideline.

The doses in the table below stay under the established safe upper limit. According to the NRC's 2006 report, published in TVP's article, dogs can safely have up to 370 mg combined EPA+DHA per kg metabolic body weight, which is roughly 2,080 mg/day for a 10-kg (22 lbs) dog.

The dog's size and overall health status are critical when determining the fish oil dose. Other deciding factors are the dog's life stage and the amount of omega-3s in the diet.

Growing puppies need higher fish oil doses for proper brain and eye development, while seniors need DHA to support cognition.

Different commercially available pet food brands have varying amounts of EPA + DHA, which affects a dog's need for additional omega-3 supplementation.

Always talk to your veterinarian before adding fish oil to your dog's daily routine. Whether a dog needs and benefits from omega-3 supplementation, and if it does, which dose is best, depends on many factors and warrants professional evaluation.

The need to consult a veterinarian regarding fish oil for dogs is even greater if the supplement is necessary in higher doses as an add-on tool in osteoarthritis management.

What's the Difference Between EPA and DHA?

EPA and DHA differ in their chemical structure. Because they are built differently, EPA and DHA have unique roles in the body and are needed at specific life stages.

For example, EPA can help control inflammation at any adult stage, while DHA is vital at the beginning (puppies) and end of life (senior dogs), and for pregnant and nursing dogs.

Eicosapentaenoic acid (EPA), often called "the anti-inflammatory specialist," fights inflammation throughout the body. It works by competing with pro-inflammatory molecules.

EPA helps soothe arthritic pain and joint discomfort, aids overall skin and coat health by fighting allergies, and supports a healthy heart and kidneys.

A 2026 study compared the effects of EPA and DHA on damaged intestinal cells. In the study, DHA failed to relieve oxidative injury and inflammation, while EPA showed potent "antioxidant and anti-inflammatory" properties.

Docosahexaenoic acid (DHA), also called "the structural builder," helps build and maintain brain and eye tissue. Basically, it acts as a structural building block in the cell membranes of the brain, nerves, and retina.

DHA is critical for proper cognitive and visual development in young puppies. It also supports learning, memory maintenance, and mental sharpness in aging dogs with declining cognition.

Puppies fed high-DHA fish-oil-fortified food from 8 to 52 weeks showed significantly better reversal-task learning, visual contrast discrimination, and early psychomotor performance than moderate- and low-DHA groups, according to a study that included 48 Beagles.

Fish oil supplements can contain different EPA-to-DHA ratios. Since both omegas are different, there is no ideal ratio - it all depends on what your dog needs.

What Are the Side Effects of Fish Oil for Dogs?

Mild digestive upset, including vomiting, diarrhea, gas, bad (fishy) breath or a fishy overall odor, and greasy/oily coats, are the most common side effects of fish oil for dogs. Weight gain is also possible because fish oil is a high-fat, high-calorie supplement.

Pancreatitis (inflammation of the pancreas), increased bleeding (fish oil changes how platelets work), and allergies can occur in some dogs and are considered more severe side effects.

Dogs with sensitive tummies and dogs given high doses of fish oil are more likely to experience side effects.

Overdosing dogs on fish oil is hard. According to the NRC, the safe upper limit for dogs is 370 mg of combined EPA+DHA per kg of metabolic body weight, which equals roughly 2,080 mg/day for a 10-kg dog.

Going over the top is hard but not impossible. Unnecessarily high doses of fish oil can cause serious side effects. Potential adverse effects of high-dose omega-3s in dogs include altered platelet function, GI upset, and weight gain, according to an AVMA study.

Dogs are more likely to react poorly to fish oil if it is rancid. Incorrect storage, like keeping the bottle at room temperature, exposed to humidity and sunlight, or in clear plastic, turns the oil rancid quickly.

Call the veterinarian immediately if your dog shows digestive upset or other side effects after adding fish oil supplements to its daily routine.

Ask the vet before starting your dog on fish oil, as the supplement may interact with certain medications, such as anticoagulants and non-steroidal anti-inflammatory drugs (NSAIDs).

How Do You Choose a High-Quality Fish Oil?

The EPA-to-DHA ratio and concentration, third-party testing certificates, triglyceride form, and sustainable sourcing from cold-water species are the four criteria you need to consider when choosing a high-quality fish oil.

• Labeled EPA and DHA Amounts. Pay attention to the specific, labeled EPA and DHA amounts rather than the total fish oil content. EPA and DHA have different roles and benefit dogs in distinct ways. Therefore, you must know the exact amount of each in the fish oil supplement.
• Third-Party Testing Certificates. Choose third-party tested fish oil with certificates from independent laboratories. IFOS (International Fish Oil Standards) is the ultimate testing program for fish oil and grades the products based on EPA and DHA concentration and purity. Other important certificates include GOED (Global Organization for EPA and DHA Omega-3s), which sets global standards for fish oil production, and the NASC (National Animal Supplement Council) seal, confirming the manufacturer has passed a third-party audit for quality control and compliance.
• Triglyceride Omega-3 Form. Always opt for natural triglyceride forms over ethyl-ester or synthetic formulas. The triglyceride form has higher bioavailability, meaning the dog's body can digest, absorb, and use it more easily.
• Cold-Water Species Sourcing. Ensure the fish oil is sourced from cold-water species such as salmon, anchovies, sardines, or mackerel. Regardless of your personal level of eco-friendliness, it is highly advisable to choose sustainable sourcing. Buy fish oils from sustainable fisheries that use responsibly harvested wild-caught fish.

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Conclusion

Fish oil for dogs is a researched and scientifically supported supplement. Its beneficial effects come from two main components: EPA and DHA.

EPA has anti-inflammatory properties that benefit dogs with osteoarthritis, kidney disease, skin issues, and heart problems. DHA acts as a structural component essential for proper brain and eye development and function.

Fish oil, despite its proven effects, remains a supplement. It is not a magical cure and should not replace standard treatments.

Always consult your trusted veterinarian before giving your dog fish oil or any other supplement. You can also ask the vet to help you choose the best fish oil for your dog.