Fish Oil Supplements for Dogs: Everything You Need to Know

Fish Oil Supplements for Dogs - A Breakdown

Fish Oil Supplements for Dogs: Everything You Need to KnowFish oil supplements for dogs have been taking over the pet industry market recently.

Even though fish oil supplements for dogs are among the most popular dog supplements, many dog owners are still unsure whether they should use this with their pets or not.

So how much do we actually know about giving fish oil to dogs, and do these supplements even work in canines?

Fish oil is given to dogs as an ingredient in supplements because it contains large concentrations of fatty acids.

As we have discussed in our dog supplements terminology article, fatty acids are important for all systems of the body to function normally, for example respiratory and circulatory systems, brain, skin and other organs.

There are two main classes of fatty acids we are interested in here – the omega-3’s and the omega-6’s.

In humans, fatty acids are associated with reduced risk of cardiovascular disease, decreased adverse events in people with heart disease, and benefits for patients with inflammatory disorders.

Omega-3 fatty acids include:

  • Alpha-linolenic acid (ALA)
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

Omega-6 fatty acids include:

  • Linoleic acid (LA)
  • Gamma linolenic acid (GLA)
  • Dihomo-gamma-linolenic acid (DGLA)
  • Arachidonic acid (AA)

There is a third class of fatty acid that is commonly mentioned, the omega-9 fatty acids.  These decrease the concentrations of omega-3 and omega-6 fatty acids in the blood and skin.

Why do dogs need fish oil supplements?

Giving fish oil to dogs have been associated with many health benefits.

Animals can produce some, but not all, the fatty acids they need. Those fatty acids which they are unable to produce themselves are known as “essential” fatty acids.  These must be obtained through the diet.

What is ‘essential’ for one species of animal is not necessarily essential for another. Supplementing with fish oil ensures your dog will get all the essential fatty acids it needs.

In some disease conditions, enzymes which convert fatty acids to others may be insufficient, or the animal’s intestine may be unable to adequately absorb fatty acids.

Under these circumstances, fatty acids considered to be “non-essential” may become “essential”, i.e. required in the diet.

Fatty-acid deficiencies may also occur with the use of fat-restricted diets in overweight dogs.

If you make your dog’s food yourself, there are several factors to consider with regards to whether you should provide fish oil supplement as well as include other vitamins for dogs.

Fatty acids in foods degrade relatively easily and they can be destroyed by overcooking. Improper storage or a sub-optimal amounts of dog anti-oxidants in dry food may also result in fatty acids degrading.

Sources of fish oil

Fatty acids are found in many plants. Sunflower oil and safflower oil are especially high in LA.

Most commercially available fish oil supplements for dogs are derived from cold-water fish, primarily menhaden, but also sardines, herring, salmon and trout. Marine oils are good sources of EPA and DHA.

Fish oil is extracted for supplements which can be purchased for your dog as edible capsules, chewable tablets or liquid products.

Additionally, you can also give fish to your dog on occasion to supplement your pet’s diet with EFAs even further.

Benefits of fish oil supplements for dogs

Fish Oil Supplements for Dogs - Everything You Need to KnowInitially, fish oil was used as a supplement for dogs to treat allergies. However, it is now recommend by veterinarians for a wide variety of conditions ranging from kidney disease to canine arthritis and high cholesterol.

Some owners of perfectly healthy dogs add fish oil to their pets’ food at every meal for general health maintenance.


Fish oil in your dog’s diet can provide anti-inflammatory effects.  It can therefore help relieve itching from allergy-related skin conditions.

Other diseases which can be associated with inflammation (e.g. ulcerative colitis, inflammatory bowel disease, rheumatoid arthritis) may respond to the anti-inflammatory effects of certain fatty acids.

Allergies and autoimmune conditions

Dogs may develop allergies or autoimmune conditions. These occur because the immune system over-reacts.

Certain fatty acids in fish oil supplements for dogs can lessen the harmful effects of this over-reaction.

Canine arthritis

Omega-3 fatty acids, notably EPA, may be helpful in reducing the inflammation involved in arthritis of dog joints.

Dull and dry hair coat

Dogs with coats that are dull, brittle and dry, often respond to supplementation with fatty acids, especially LA, contained in fish oil.

It has also been found that in some cases of mild dermatitis (seborrhea), there is a deficiency of LA in the skin which can be reversed by supplements high in this fatty acid.

The addition of EPA and GLA is also beneficial in that it reduces the release of AA from cells damaged because of this skin condition.

Yeast infections

Fatty acids slow the growth of M. pachydermatis, a common yeast infection on the skin and ears of dogs.


Fish oil supplements for dogs may be useful to prevent atopy (allergies to inhaled substances such as pollens and molds) from developing, particularly in puppies and young dogs.

Supplementation of bitches in late pregnancy may help boost the development of the immune system of her pups to avoid these.

Eye health

Omega-3 fatty acids are essential for the proper development of the visual system in canines.

Again, fish oil supplementation of pregnant bitches may help the proper development of her pups.

Heart and vascular problems

Omega-3 fatty acids may prevent irregular heartbeats in dogs, and high blood pressure may also be reduced.

Dogs prone to blood clotting may be helped by the anti-clotting effect of fatty acids, especially when combined with Vitamin K1.

Canine cancers

Omega-3 fatty acids have been reported to slow the progression of some cancers.

Plasma triglycerides and cholesterol

Fish oils have been shown to decrease levels of lipids and cholesterol in the blood.

Animals receiving therapy with synthetic vitamin A for various skin problems may develop elevated levels of lipids in the blood (hyperlipidemia). Fish oil supplements for dogs may benefit those suffering from this condition.


Omega-3 has been reported to have a calming effect on some nervous dogs.

Synergistic effects

Omega-3 fish oil helps antihistamines and glucosteroids work more effectively.

This cooperative effect means the dog can take lower doses of these medicines.

Toxicity and side effects of fish oil supplements

In dogs

Fish Oil Supplements for Dogs and PetsIn dogs given overly-high doses of fish oil supplementation, the most serious side effect is inflammation of the pancreas (pancreatitis), although this is rare. This condition can cause intestinal problems such as abdominal pain, loose stools, vomiting which may result in dehydration.

Omega-3 fatty acids have anti-coagulant effects beneficial for cardiovascular problems. However, over-supplementation can lead to increased and prolonged bleeding. Dogs with bleeding disorders should not take fish oil without veterinarian consultation.

Some dogs given fish oil may develop ‘fishy’ breath, oily hair or yellow skin flakes.

In humans and other animals

In humans (and therefore potentially in dogs), the most common negative effects of fish oil are gastrointestinal.

These effects can include a fishy aftertaste, bad breath, burping, heartburn and abdominal bloating and pain.

High doses of fish oil may cause nausea, loose feces and diarrhea. A reduction in the inflammatory response can decrease the effectiveness of the immune system

In rats, the immune system can become suppressed with daily doses as low as 0.9 g EPA and 0.6 g DHA.

Small decreases in blood pressure can also occur when taking omega-3 fatty acid supplements.

Omega-6 fatty acids have been shown to stimulate tumor development.

Dosage of fish oil supplements for dogs

Before giving your dog fish oil supplements (whether it is intended for humans or pets), consult your vet, particularly with regard to dosage. Dogs with allergies may need higher than the standard dosages.

Omega-3 fish oil is usually given up to 20 mg/lb as a daily dose. When given as a dietary supplement, the label recommendations should be considered as guidelines and may be significantly increased by veterinary advice.

Dosage levels may vary according to the product you are using because the supplement may contain other ingredients or additives.

Fish oil intended for humans can be used for dogs. If you use these, give larger dogs a capsule or two (depending on the dosage) and puncture a capsule to squeeze some of the contents into the food of smaller dogs.

If you are giving your dog fish oil for therapeutic reasons, you may not see results for 9-12 weeks.

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