Krill Oil vs Fish Oil for Dogs: Which One Is Actually Better?

If you have started seeing krill oil appear in dog supplements and wondered whether it is actually any better than the fish oil you have always known, you are asking the right question. Both of them do the same basic job; giving your dog the healthy fats called omega-3s that their body cannot make on its own. The difference is in how well the body uses them and what else comes along with them.

What Are They and Where Do They Come From?

Fish oil is made from small oily fish like sardines and anchovies. It has been around in pet supplements for years, it is well studied, and it is the cheaper of the two options.

Krill oil comes from tiny shrimp-like crustaceans called krill that live in cold Antarctic waters. They sit very low in the ocean food chain, which means they accumulate fewer pollutants and contaminants compared to larger fish. That makes krill oil one of the cleaner omega-3 sources available.

Both contain the two omega-3 fatty acids that most benefit your dog: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These are associated with better joint health, a shinier coat, healthier skin, and immune system support.

Does the Body Absorb Them Differently?

Yes, and this is an area where krill oil has a potential advantage. Fish oil omega-3s are bound to triglycerides, which require digestion before absorption. Krill oil omega-3s are predominantly bound to phospholipids, a form that is absorbed more readily in the small intestine. Several human studies have reported higher bioavailability of krill oil omega-3s compared to fish oil at equivalent doses. However, direct comparative pharmacokinetic studies in dogs are limited, and the degree of difference in dogs specifically has not been firmly established in peer-reviewed literature.

What this means in practice is that your dog may get more benefit from a smaller amount of krill oil compared to fish oil. Fish oil absolutely works but the phospholipid form in krill oil is considered more bioavailable.

The Real Difference: Krill Oil Comes with a Built-In Bonus

Krill oil naturally contains astaxanthin, a carotenoid antioxidant that gives krill their distinctive pink-red colour. It serves two meaningful functions in a supplement context.

First, astaxanthin acts as a natural preservative, protecting the omega-3 fatty acids from oxidation. Oxidised fish oil — recognisable by a strong, rancid fishy smell — contains lipid peroxides that may be harmful rather than beneficial. Krill oil's natural astaxanthin content significantly reduces oxidation compared to plain fish oil, which has no equivalent built-in antioxidant protection.

Second, astaxanthin has independent antioxidant and anti-inflammatory properties. In animal studies, astaxanthin has demonstrated anti-inflammatory effects via inhibition of pro-inflammatory cytokines and NF-kB pathways. Studies specifically in dogs are limited, but the ingredient is increasingly included in veterinary supplement formulations on the basis of this broader evidence.

Are There Any Reasons to Stick with Fish Oil?

Yes, two main ones.

Cost is the significant one. Krill oil costs more per gram than fish oil. If budget is a genuine concern, a good quality fish oil dosed correctly will still provide your dog with meaningful omega-3 benefits.

The other is shellfish sensitivity. Krill are crustaceans — the same biological class as prawns and lobster. If your dog has a known reaction to shellfish or crustaceans, krill oil is best avoided and fish oil is the safer choice. There is currently no published research confirming cross-reactivity between krill oil and shellfish allergens in dogs specifically; however, given the shared protein structures, veterinary guidance typically advises caution in sensitised animals.

What Do Omega-3s Actually Do for Your Dog Day to Day?

Whether you go with krill or fish oil, here is what consistent omega-3 supplementation does for most dogs over time.

Joints

Omega-3 fatty acids — specifically EPA — help modulate the inflammatory cascade in joint tissue, which can ease stiffness and discomfort. This is especially relevant for older dogs or those showing early signs of osteoarthritis. The American Animal Hospital Association (AAHA) Canine Life Stage Guidelines include omega-3 fatty acid supplementation as a recommended nutritional support strategy for dogs with osteoarthritis.

Coat and Skin

Dogs receiving adequate omega-3s tend to have shinier, softer coats and reduced shedding. Omega-3s help maintain the skin barrier, which reduces dryness, flakiness, and irritation. Dogs with atopic dermatitis or seasonal skin sensitivities often show measurable improvement with consistent supplementation.

Note: the evidence for omega-3s in canine atopic dermatitis specifically is moderate rather than definitive. A Cochrane-style review of veterinary dermatology trials found mixed results, with some studies showing clear benefit and others showing modest effects. Consistent daily dosing at appropriate levels appears to be the key variable.

So Which One Should You Choose?

For most dogs, krill oil offers a meaningful advantage in bioavailability and oxidative stability. The phospholipid form is more readily absorbed, and the presence of astaxanthin provides antioxidant protection that plain fish oil lacks. If you are looking at a supplement that already includes krill oil as part of a wider formula, you are covering the omega-3 angle efficiently without needing a separate product.

If budget is a concern or your dog has a history of shellfish sensitivity, a quality fish oil product given consistently at the correct dose for your dog's body weight will still deliver real omega-3 benefits. As a general guide, commonly cited therapeutic doses for EPA+DHA in dogs range from approximately 20 to 55 mg per kg of body weight per day, but always follow product labelling and consult your veterinarian for dose guidance specific to your dog's condition and size. The most important thing is that your dog gets omega-3s consistently, whichever source you choose.

For more on what a comprehensive daily supplement covers across all ingredient categories, our guide on canine multivitamin benefits breaks it all down in plain terms.

Pambros Total Vitality Blend™ includes Antarctic krill oil alongside a full vitamin and mineral complex, eggshell membrane collagen, PurforMSM, glucosamine, and a 6-strain probiotic blend — one daily chew that covers the omega-3 side and everything else at the same time.

DISCLOSURE: This content was created in partnership with Pambros. Scientific claims have been independently fact-checked by Dr.Muqeet Mushtaq, DVM, MS - a licensed veterinarian and animal genetic scientist with over 9 years of experience in veterinary medicine and pet health. Dr. Mushtaq holds a Doctor of Veterinary Medicine from the University of Animal and Veterinary Sciences and an MSc in Animal Breeding & Genetics. He is a regular contributor to leading pet and veterinary publications worldwide.