If your dog has been getting a daily drizzle of flaxseed oil, they may be receiving far less functional omega-3 support than you intended. Fish oil works differently, and understanding why matters for every dog parent thinking seriously about long-term wellness.
What Fish Oil Is and Why the Source Matters
Fish oil is a fat extracted from cold-water marine fish species, most commonly anchovies, sardines, and pollock. These forage fish live short lives and feed low on the food chain, which means they accumulate fewer environmental contaminants than larger, longer-lived species like tuna or salmon.
The two fatty acids that make fish oil valuable are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Both are long-chain omega-3s that arrive in a form the body can incorporate into cells and tissues without further modification. Plant-based oils, including flaxseed, chia, and hemp, contain a different omega-3 called ALA (alpha-linolenic acid). ALA must be converted by the body into EPA and DHA to have the same biological effects, and dogs have a very limited capacity for that conversion. Research comparing direct EPA and DHA supplementation against flaxseed oil supplementation in dogs found that flaxseed oil raised only ALA levels, while preformed EPA and DHA produced measurable increases in circulating long-chain omega-3s [1]. That is the core reason marine-derived oils are relied upon when meaningful omega-3 support is the actual goal.
What EPA and DHA Do in a Dog’s Body
EPA plays a direct role in how the body manages its response to inflammation. Cells throughout the body contain fatty acids in their membranes, and those fatty acids become the raw material for signaling molecules called eicosanoids. Omega-6 fatty acids tend to produce pro-inflammatory eicosanoids. EPA competes with those omega-6s for the same enzymes and produces eicosanoids that support a more controlled inflammatory response. When EPA is present in sufficient amounts, the body has more capacity to regulate inflammatory activity, rather than simply amplify it.
DHA serves a different but no less significant role. It is a structural fat, integrated into the physical makeup of nerve cells, brain tissue, and the retina. Adequate DHA levels may help support cognitive function in dogs and visual acuity at every life stage, from puppies in development to senior dogs experiencing age-related neurological changes.
Both fatty acids are also associated with joint tissue health. Research on omega-3 fatty acids and osteoarthritis in dogs has established that EPA and DHA reduce the production of prostaglandin E2 in cartilage and compete with arachidonic acid for the enzymes that drive inflammatory signaling, while also limiting the activity of matrix metalloproteinases, the enzymes primarily responsible for breaking down cartilage [2]. Multiple controlled trials in dogs with confirmed osteoarthritis have demonstrated that EPA and DHA supplementation produces significant improvements in discomfort and lameness scores compared to placebo [2]. This is why marine omega-3 supplementation has become one of the more studied areas in canine nutrition for dogs with joint concerns.
Why Most Commercial Diets Leave Dogs Short
Diet can play a meaningful role in inflammation because the gut is closely connected to the immune system. Every time a dog eats, the body has to decide what to accept and what to react to. If the gut is out of balance, whether from highly processed food, poor-quality fats, or an unhealthy mix of gut bacteria, the immune system can become more sensitive over time. That ongoing sensitivity may show up as skin irritation, recurring digestive trouble, or low-level joint inflammation.
The majority of commercial kibble is low in EPA and DHA. The dominant fat sources, including poultry fat, corn oil, and sunflower oil, are rich in omega-6 fatty acids, incorporated because of cost and palatability. Omega-6 fats are not inherently problematic. They support cell growth, skin integrity, and immune activity. The issue arises when they dominate the diet without enough omega-3s present to balance them, which is exactly the condition that keeps the immune system on a low-grade alert.
Fish oil provides EPA and DHA in their active form, helping restore a more favorable fat ratio and giving the immune system a broader set of tools to regulate its response.
Supporting gut balance is part of this picture too. A significant portion of the immune system is housed in the digestive tract, and a well-functioning microbiome may help keep systemic inflammation in check. This is where a digestive health supplement can work alongside an omega-3 routine. Bernie’s Perfect Poop combines fiber from Miscanthus grass, grown in Missouri and Arkansas, with prebiotics, hardy spore-forming probiotics including Bacillus Subtilis and Bacillus Coagulans, and digestive enzymes. It comes as grass bits in natural cheddar or chicken flavor, and it is grain-free and gluten-free. Bernie’s Perfect Poop has been used by and has supported digestive wellness for millions of dogs.
Where the Research Points
Research on marine omega-3s has identified several areas where consistent supplementation may provide meaningful support.
Skin and coat response is one of the most studied applications. EPA and DHA contribute to the skin’s barrier function, which serves as the primary physical defense against allergens, environmental irritants, and moisture loss. A randomized placebo-controlled study in dogs with poor coat quality found that clinical scores improved significantly from day 60 of EPA and DHA supplementation and that lipid content in hair shafts increased progressively in the supplemented group [3]. Those managing chronic skin sensitivity or a dull, dry coat may see benefit from improved omega-3 status.
Research on joint comfort points in a similar direction. A 16-week clinical study in 29 adult dogs found that daily supplementation with approximately 70 mg of EPA and DHA per kilogram of body weight significantly increased the Omega-3 Index across all dogs and reduced discomfort scores, primarily in small and medium-sized dogs, with no adverse effects reported [4].
Cognitive function, particularly in aging dogs, is an area where DHA’s structural role in brain tissue is most relevant. Adequate levels may help maintain neurological health as dogs grow older. Veterinarians may also suggest omega-3 support for dogs with cardiovascular concerns or chronic kidney disease, though those are cases where individualized veterinary guidance is recommended before beginning supplementation.
When to Be Thoughtful About Dosing
Fish oil is well-tolerated by most healthy dogs. A few specific situations do warrant extra care.
Dogs with pancreatitis or fat-processing conditions, including hyperlipidemia, may need veterinary input before adding any dietary oil. Even a beneficial supplement can place additional stress on a digestive system that is already compromised.
Research has noted that very high doses of EPA and DHA can increase oxidative stress markers and reduce vitamin E levels in some dogs, because vitamin E protects these fatty acids from oxidative damage in the body [5]. The National Research Council has established a safe upper limit of 2,800 mg of combined EPA and DHA per 1,000 kcal for dogs [5]. Staying within appropriate ranges for a dog’s size and health status matters, and a veterinarian can help with that calculation.
Oxidation is also worth monitoring. Fish oil is sensitive to heat, light, and oxygen. Oil that smells noticeably sour or rancid, beyond a mild, normal fish odor, may already have degraded and should be replaced. Oxidized oil does not deliver the intended benefit and may introduce cellular stress rather than reduce it.
Formats: Liquid, Chews, and Capsules
Fish oil for dogs is available in several forms, and the right choice often depends on a dog’s preferences and the household routine.
Liquid oil allows for flexible dosing and typically delivers higher concentrations of EPA and DHA per serving than other formats. It can be added directly to food and is easy to adjust by body weight. The trade-off is that liquid oil requires refrigeration after opening and has a shorter shelf life once exposed to air.
Soft chews are convenient and well-suited to dogs who resist pills or dislike the smell of liquid oil. When evaluating a chew-format product, check the label for specific EPA and DHA amounts per chew rather than relying on general “omega-3” figures. A high ALA content on the label may indicate the product is relying on plant-based oil rather than fish-derived sources [1].
Gel capsules offer pre-measured dosing and good stability because the oil stays sealed from air until opened. Many dog parents puncture the capsule and squeeze the contents onto food. Once exposed, the oil should be used promptly to limit oxidation.
What to Look for When Choosing an Omega-3 Product
The quality of omega-3 supplements varies considerably. A few factors are worth checking before buying:
- Specific EPA and DHA amounts per serving listed on the label, not just “total omega-3” or “total fish oil”
- Fish species used: small forage fish like anchovies, sardines, or pollock are preferable to larger species that may carry higher contaminant levels
- Evidence of third-party testing for heavy metals and environmental toxins
- Natural antioxidants such as vitamin E or mixed tocopherols added to slow oxidation
- Clear, weight-based dosing guidance designed for dogs
Why Bernie’s OMG! Omegas Is Built for This
Bernie’s OMG! Omegas is formulated specifically around what dogs actually need from an omega-3 supplement: verified EPA and DHA amounts per serving, marine sourcing that prioritizes forage fish and algae, natural absorption support, and no additives that raise safety questions for canine use.
The soft chews, OMG! Omegas Chews, come in two flavors dogs respond to: pork and salmon, 90 chews per bag. Each 3g chew delivers a minimum of 140 mg EPA and 125 mg DHA, drawn from anchovy oil (150 mg per chew) and marine microalgal oil (125 mg per chew). That algal oil is cultivated in sterile facilities, removing the environmental contamination concerns associated with larger wild-caught species. The formula includes natural vitamin E (52 IU per chew) and green tea extract (20 mg per chew), which support absorption and bioactivity rather than simply delivering the fatty acids. The formula is made in the USA, GMP and SQF certified, grain-free, and free from artificial colors or flavors. Dosing scales by weight: one chew daily for dogs up to 25 pounds, two for 26 to 50 pounds, three for 51 to 75 pounds, four for 76 to 100 pounds, and five for dogs over 100 pounds.
An oil version, Bernie’s OMG! Omega Oil, is also available for dog parents who prefer a liquid format. The oil uses marine microalgal oil and wild Alaskan pollock oil as its primary EPA and DHA sources, with grape seed oil and natural vitamin E for absorption support. It is added directly to food and mixed in, with no strong fishy odor. Like the chews, it is free from artificial additives and grains and is appropriate for dogs of any breed or age.
Both formats are backed by the Growl-Free Guarantee.
Try It Risk-Free
If your dog’s current routine relies on a plant-based oil as the primary omega-3 source, it may be worth reconsidering whether they’re getting what you think. Marine-derived EPA and DHA are the forms dogs can actually use [1], and consistent supplementation may support skin and coat health, joint comfort, and cognitive function throughout their life.
Bernie’s OMG! Omegas delivers marine-sourced EPA and DHA in a formula made specifically for dogs, available as soft chews in pork or salmon flavor or as a concentrated oil. Every bag and bottle comes with the Growl-Free Guarantee. If your dog doesn’t love them or you’re not seeing the results you hoped for, you get your money back. Try it risk-free.
Frequently Asked Questions
Is fish oil safe for dogs to take every day?
For most healthy dogs, daily fish oil supplementation is safe when given at appropriate amounts for their size and diet. The benefits of EPA and DHA tend to build with consistent use rather than appearing all at once [4]. Dogs with pancreatitis, hyperlipidemia, or other fat-processing conditions should have veterinary guidance before adding any oil to their routine. Starting at a lower amount and building up gradually is generally a good approach, as it allows the digestive system to adjust.
Can I give my dog human fish oil capsules?
In many cases, a single plain capsule is not harmful, though dog-specific formulations are preferable for regular use. Human fish oil capsules often contain appropriate amounts of EPA and DHA and do not typically include ingredients harmful to dogs, but they come in fixed sizes that may not align with what a specific dog actually needs, and they lack weight-based dosing guidance. If using human capsules, checking the specific EPA and DHA content per capsule and calculating an appropriate amount for your dog’s size is worth confirming before starting. Any product containing xylitol or other artificial sweeteners should not be given to dogs under any circumstances.
What is better for dogs: fish oil or flaxseed oil?
For delivering EPA and DHA, fish oil is the more effective option. Dogs convert the ALA in flaxseed oil into EPA and DHA at less than 10% efficiency, which means most of the intended omega-3 benefit does not translate into the active forms the body can use [1]. Flaxseed oil does offer other benefits, including ALA alongside fiber content when whole seeds are used, but it does not substitute for marine-derived omega-3 support. If joint health, skin response, or inflammatory balance are the goals, fish oil is the more direct path.
Are there any side effects of fish oil in dogs?
Fish oil is well-tolerated by most dogs. Some may experience mild digestive upset when starting or when amounts are increased too quickly. Starting at a lower amount and building up over time tends to reduce that. At very high doses, research has noted potential concerns including increased oxidative stress and reduced vitamin E levels in some dogs [5]. Staying within recommended ranges and choosing a product that includes natural antioxidants helps address those concerns. Dogs with fat-related conditions, including pancreatitis, need veterinary guidance before starting.
How much fish oil should I give my dog?
There is no single answer because appropriate amounts vary by a dog’s weight, diet, and health status. The National Research Council has identified a safe upper limit of 2,800 mg of combined EPA and DHA per 1,000 kcal for dogs [5]. For dogs with specific health conditions, a veterinarian can help determine a therapeutic target. For general wellness support, premium dog supplements with clear weight-based dosing guidance take most of the guesswork out of the process and reduce the risk of over-supplementing.
SOURCES
[1] Dominguez TE, Kalinowski CR, Suchodolski J, et al. “Enhanced omega-3 index after long- versus short-chain omega-3 fatty acid supplementation in dogs.” Veterinary Medicine and Science. 2021;7(3):819-828. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC8025612/ – canine study comparing flaxseed oil (ALA only) vs. marine omega-3s; flaxseed oil raised only ALA levels with no meaningful increase in circulating EPA or DHA, while preformed marine EPA and DHA produced significant measurable increases. Applied to ALA conversion claim, marine sourcing rationale, and chew format label guidance.
[2] Henrotin Y, et al. “Nutrition and nutraceuticals in the changing management of osteoarthritis for dogs and cats.” Journal of the American Veterinary Medical Association. 2020;256(12). https://avmajournals.avma.org/view/journals/javma/256/12/javma.256.12.1335.xml – peer-reviewed review confirming EPA and DHA decrease prostaglandin E2 production in cartilage, compete with arachidonic acid for COX/LOX enzymes, and reduce matrix metalloproteinase expression by 37% in synovial fluid. Corroborated by Mehler SJ et al. randomized double-blind placebo-controlled canine OA trial: https://pubmed.ncbi.nlm.nih.gov/27269707/ – all clinical outcomes improved significantly vs. placebo at day 84.
[3] Guillot M, Serisier S, Lavelle R, et al. “A prospective, randomized, double blind, placebo-controlled evaluation of the effects of an n-3 essential fatty acids supplement on clinical signs, and fatty acid concentrations in the erythrocyte membrane, hair shafts and skin surface of dogs with poor quality coats.” Veterinary Dermatology. 2020. https://www.sciencedirect.com/science/article/pii/S0952327820300983 – clinical scores significantly reduced from day 60 of EPA/DHA supplementation in dogs with poor coat quality; lipid content in hair shafts increased progressively in supplemented group.
[4] Harris WS, Klatt C, Stetter L, et al. “The effects of omega-3 supplementation on the omega-3 index and quality of life and pain scores in dogs.” Animals. 2024;14(21):3108. PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC11545626/ PubMed: https://pubmed.ncbi.nlm.nih.gov/39518831/ – 16-week open-label study in 29 adult dogs at 5 US veterinary clinics. At approximately 70 mg EPA+DHA/kg/day sourced from anchovy and sardine oils, the Omega-3 Index increased significantly across all dogs; discomfort scores declined primarily in small and medium-sized dogs. No adverse effects. Note: study was open-label (no placebo control) and had industry funding disclosures; cite alongside the controlled trials in [2].
[5] Lenox CE, Bauer JE. “Potential adverse effects of omega-3 fatty acids in dogs and cats.” Journal of Veterinary Internal Medicine. 2013;27(2):217-226. PubMed: https://pubmed.ncbi.nlm.nih.gov/23323770/ – peer-reviewed review documenting potential adverse effects including increased lipid peroxidation and reduced vitamin E in some dogs on higher EPA/DHA diets. National Research Council safe upper limit of 2,800 mg EPA+DHA per 1,000 kcal referenced from NRC Nutrient Requirements of Dogs and Cats (2006). Summarized at Bernie’s University: https://www.bernies.com/university/research-paper/potential-adverse-effects-of-omega-3-fatty-acids-in-dogs-and-cats/
