If You Feed Your Dog Fish Oil, Should You Also Give Vitamin E?

Updated on August 12, 2019
alexadry profile image

Adrienne is a certified dog trainer, former veterinary assistant, and the author of "Brain Training for Dogs."


You may have heard from other dog owners or from the online forums about how fish oil may be good for your dog. But is it really true? There seems to be a surge in the tendency for dog owners to give supplements to dogs, but how much research is put into learning about potential side effects and what about interactions with other drugs? We often assume that just because a supplement is sold over the counter and is natural that there are few risks, but this is often far from true. Let's take a look at fish oil for instance, how does fish oil affect dogs and what do we need to be aware of so we can make an informed decision?

Fish Oil

Your favorite drug store has plenty of bottles on stock, but how good is it? And what benefits does it bring?

First off, what is really fish oil? It comes in some appealing amber-colored capsules, but what is in it exactly? Apparently, it's an oil derived from the tissues and belly cavity of oily fish. What fish are considered good candidates for producing fish oil? Generally, the most common fish used are oily fish derived from cold waters such as salmon, herring, mackerel, anchovies, and sardines. Not many foods on this planet contain omega-3 fats, the most common source being the fat of cold-water fish.

Fish oil is known for containing beneficial eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are commonly known as omega-3 fatty acids. Fish produce these fatty acids by eating microalgae or other fish that are rich in omega 3s.

Fish oil should contain vitamin E as an antioxidant, but no other nutrients.

— Etienne Côté. DVM, Dipl.ACVIM.

Should Dogs Who Are Given Fish Oil Be Supplemented With Vitamin E?

You may have read about the benefits of fish oil for dogs, but you may not be aware of its exact effects on your dog's body. As with many things in life, too much of a good thing can lead to many problems. And even if you heard about giving vitamin E to dogs on top of giving fish oil, you may not know why, even though you feel compelled to give it, just because.

An explanation can be found from a study published by the Turkish Journal of Medical Sciences. The paragraph states:

"Besides these positive effects of fish oil, increased levels of long-chain n-3 fatty acids may render membranes more susceptible to oxidation and may increase the requirement for antioxidants."

Vitamin E is known for being an antioxidant. Antioxidants play a major role in protecting cells from toxic free radicals, known for contributing to several conditions such as aging, cancer and cardiovascular disease in humans.

Perhaps one of the most dramatic stories concerning fish oil in dogs is one published by Dogs Naturally Magazine. An owner had given her 3-year-old Neapolitan mastiff 8 fish oil capsules when the dog was unable to get up. Her research led to the assumption that her dog may have suffered from a vitamin E deficiency. This was further proven as, once her dog was given vitamin E, the symptoms disappeared. The entire story can be found on the owner's post on Dog Forums.

Talk to Your Vet Before Giving Supplements

While adding vitamin E to fish oil may sound like a good idea, there are also risks to consider. Yes, combined, these two supplements work in synergy providing potent anti-inflammatory benefits, they also both help promote skin health and they work wonders for healthy brain function, but when taken together they may thin the blood, something problematic if a dog needs surgery or is on some other medications that may interact. This is why it's always a good idea to talk with a vet before giving your dog supplements, just to play it safe.

Fish oil supplements should contain vitamin E as an antioxidant, but other nutrients should not be included.

— Tufts University
Rex - Gone Fishing
Rex - Gone Fishing | Source

Today, many fish are highly contaminated with industrial pollutants and toxins such as mercury, PCBs, heavy metals, and radioactive poisons. Another problem with fish oil is its lack of natural antioxidants. When you use fish oil, extra antioxidants can help to protect the fatty acids from oxidization.

— Dr, Karen Becker

Is Fish Oil Really Good for Dogs?

At this point, you may be wondering if fish oil is really that beneficial to dogs. One concern is being depleted of vitamin E, but this can be easily replaced with supplementation. However, there are further concerns. One of them is the fact that fish oil can be easily contaminated with some relevant amounts of heavy metals and toxic chemicals. PCB's (polychlorinated biphenyls) dioxins, mercury and PCP (pentachlorophenol) are just a few.

Toxic metals are more significantly found in the tissues of larger fish because they tend to live longer, and as such, they accumulate quite large amounts of toxins in their lifetime. For instance, tuna contains a lot of metal because they are large, tend to live longer and are on the top of the food chain. Much fewer chemicals are found in smaller fish such as sardines and anchovies.

This is a big concern for humans and animals who consume fish oil supplements. Environmentalists for quite some time have shown a big concern over the illegal levels of carcinogens and chemicals in fish. What may seem like a good practice when supplementing with fish oil, may turn out being a bad depending on what type of fish oil you give your dog. Dr. Karen Becker recommends using krill oil which doesn't tend to accumulate heavy metals and provides natural antioxidant protection protecting from damage from free radicals.

Fish oil is also quite perishable and prone to getting rancid. It's best to use fish oil that is stored in dark bottles versus fish oil that is stored in clear plastic. Let fish oil get rancid, and you are stuck with a product that does more harm than good due to the accumulation of free radicals.

Fish Oils and Vitamin E: Healthy or Unhealthy?


  • Clinical Veterinary Advisor: Dogs and Cats, By Etienne Cote, Mosby; 3 edition (December 23, 2014)
  • Cummings, Veterinary Medical Center, Tufts University, Important Nutrients for Pets with Heart Disease
  • Dr. Mercola, Krill oil for dogs and cats, retrieved from the web on Sept, 7th, 2016

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


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    • alexadry profile imageAUTHOR

      Adrienne Farricelli 

      3 years ago

      Helo Suhain, I feed my dogs Orijen too, but lately they have been a bit gassy and I hope it's not because the US formula has changed too much. I really miss the Canadian version now. I have never given vitamin E to my dogs either as Orijen Senior has vitamin E as a preservative added already. However, know several people who use it for dogs with skin issues, immune system problems or just aging, but I think it's always best to consult with a vet before starting any supplements.

    • Suhail and my dog profile image

      Suhail Zubaid aka Clark Kent 

      3 years ago from Mississauga, ON

      Very informative and well researched article, Adrienne (alexadry)

      I feed my dog Orijen six pack fish and feed him neither fish oil nor vitamin E. I am not sure if I should. I have asked the breeder and the vet and they both have said that with that high quality dog food, I don't need to worry about anything.

    • alexadry profile imageAUTHOR

      Adrienne Farricelli 

      3 years ago

      The Dirt Farmer, we often tend to think that supplements don't have side effects, but they do too. Most human doctors now ask about all supplements people take because they can interact with other meds or thin the blood which is something that needs to be known before a surgical procedure.

    • alexadry profile imageAUTHOR

      Adrienne Farricelli 

      3 years ago

      Victoria, krill oil is the oil obtained from these small swimming crustaceans that I think come from the Antarctic.

    • The Dirt Farmer profile image

      Jill Spencer 

      3 years ago from United States

      Thanks for this information. We changed our dog's food and cut out all treats except for the ones I make when he developed an allergy that caused him to scratch. The allergy cleared up, but the vet recommended we give him fish oil too for his skin health. I had no idea it about its side effects.

    • Victoria Lynn profile image

      Victoria Lynn 

      3 years ago from Arkansas, USA

      Interesting stuff! What is krill oil? Does it say on the bottle? I'll be more aware from now on--dark bottles! Your hubs are always helpful.


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