Something Fishy

Dietary supplementation with fish oil has become all the rage these days as a means for maintaining a “well oiled machine”. Admittedly, I swallow fish oil capsules daily based on their proven health benefits. Not only do the fatty acids found within murine oil help protect the body against cancer, they may also benefit heart function, blood pressure, arthritis, autoimmune diseases, and gastrointestinal disorders. Additionally, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), the fish oil fatty acids responsible for the greatest health benefits, are potent mediators of inflammation, reducing deleterious or damaging inflammatory responses within the body.

So, how might fish oil benefit our furry family members? Here’s a rundown of what we know about the proven benefits of fish oil supplementation. (Our poor kitties always seem to play second fiddle- the studies performed to date pertain to dogs.)

Itchy Skin: Studies have documented that dogs with allergic skin disease who were treated with DHA and EPA experienced significant reduction in the degree of itchy discomfort along with improved appearance of their haircoats.

Heart Disease: Dogs with heart failure tend to have lowered blood levels of EPA, so it makes sense that fish oil supplementation may create benefit. Studies have documented that dogs suffering from heart failure who were treated with fish oil along with other standard medications showed decreased vulnerability to development of heart rhythm abnormalities, weight loss, and heart muscle damage.

Kidney Disease: Fish oil supplementation has been documented to reduce the potentially damaging loss of protein in the urine of dogs with kidney disease. Because of their anitinflammatory effects, fish oil appears to create some protection against ongoing damage when kidneys are diseased.

Arthritis: The antiinflammatory effects of EPA and DHA have been proven to significantly alleviate discomfort associated with arthritis in dogs. In fact, prescription diets formulated specifically for the treatment of canine arthritis are loaded to the gills with fish oil (pun intended).

As mentioned above, completed studies in kitties are lacking. Hopefully this will be changing in the near future. Studies are underway to determine if fish oil supplementation is indicated in cats with arthritis, kidney disease, allergic skin disease, cancer, and obesity.

Current canine studies are evaluating the benefit of EPA and DHA as part of the therapeutic regimen for inflammatory bowel disease, cognitive dysfunction (dementia), behavioral issues, and cancer.

Wow! Fish oil is pretty amazing stuff, don’t ya think? Talk with your veterinarian about whether or not fish oil supplementation makes sense for your little snookums. Perhaps it’s also time to talk to your own doc about “getting fishy” yourself!

Are you already adding fish oil to your pet’s diet? If so, why are you using it and what have you observed?

Best wishes,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.

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23 Comments on “Something Fishy

  1. Oh, and I also have to add, that if fish oils can help fix all this stuff, whatever the critters were eating must not have had enough.

  2. Don’t have time for a full out search, but I had read once that tissues are the best source for determining PUFA status. It appears that is true for E also.
    Good monograph on E:
    “Vitamin E is located primarily within the phospholipid bilayer of cell membranes.”
    Vit E status is often determined by serum or plasma values, which may not be accurate. This study showed normal plasma values (in men) but oxidative damage to red bloods cells.
    So quite frankly all studies which report on E levels using plasma values are suspect.
    The Vit E in fish oil caps is there to prevent oxidation of the oil in the capsule and I don’t think it is enough to prevent oxidation in the body.
    Vit E is an excellent anti-oxidant in the body and can protect from poisonings also.
    Vit E in dogs and cats:
    “Immune function is altered in vitamin E-deficient dogs and can be used as an additional indicator of vitamin E status. Vitamin E-deficient dogs had significant reduction in antibody titers to canine distemper and infectious canine hepatitis vaccines compared to normal dogs (Sheffy and Schultz, 1978). Dogs deficient in vitamin E had severe impairment of lymphocyte function as assessed by in vitro blastogenic responses to concanavalin A, phytohemagglutinin, pokeweed mitogen and streptolysin O”

    As for oversupplementation:
    “It is possible that excessively high levels of vitamin E could compete with the other fat soluble vitamins resulting in lower absorption of these necessary nutrients. For example, excessively high levels of vitamin E intake in normal dogs resulted in bleeding disorders due to an induced vitamin K deficiency (too much vitamin E “squeezed out” the vitamin K and prevented it from being absorbed at the amounts required for normal blood clotting.) Excessive levels of vitamin E have also been associated with nausea.”

    Don’t have time to read this now, but worth checking out I think:…/LeBlanc_dis.pdf
    Immunological, Hematological and Serum Biochemical Effects of High Level Dietary Fish Oil and Vitamin E Supplementation in the Dog

    ……….so I DO supplement with Vit E when I give fish oils.

  3. My 10 yr Rott, 8 yr Pom, 7 yr Yorkie and 3yr BC all get a little salmon oil once each day. A vet in Santa Barbara whose passion is nutrition in pets, Dr. Bill Campbell, told me back in the 80’s to give my dogs fish oil for the fatty acids. He pointed out the weaknesses of kibble and canned foods to me. HOWEVER, concerned about salmon and Fukushima, I am wondering what to switch to. Any suggestions? I understand the fourth tower is now on fire. Radiation continues to leak into the ocean.

  4. My 9 1/2 yo golden has kidney disease so he is taking Mega Red Plus. I am hoping after a month it will help stop the loss of protein. The other option of adding an ACE Inhibitor is a last resort. I’m trying to avoid that.

  5. Hi Amy,
    Those 3V capsules are still around- not sure why more veterinarians are not prescribing them. As much as I would love to provide you with a dosage for fish oil, without having examined your pets and learned about their complete health histories, it would not be in their best interest to do so. I strongly encourage you to pose the dosage question to your veterinarian- prescribing fish oil is so common these days that I’m sure he or she will be able to provide you with appropriate does for your dogs.

  6. My former vet used to sell 3V capsules for my foster & adopted cocker spaniels. Then I moved and none of my vets (I’ve had a series) have recommended them. They’ve been discontinued and I’d buy regular fish oil but I wouldn’t know the correct amount for my current bunch. The youngster with GI problems is 4-1/2 & weighs 22 lbs and my two oldies are 15, one of whom has arthritis. They weigh 27 & 32 (but should both weigh 30 – one lost 5 lbs after a dental & two very bad fistulae took their time healing, but he’s regained 2-1/2 lbs now). How much should they get? (all cocker spaniels of course, none of which has ear infections)

  7. I’ve been wondering if the dogs’ daily fish oil capsules are necessary, given the amount of pastured chicken and eggs that they consume. (From our own farm.) The chicken and eggs should cover the omega-3 FAs pretty well, but I don’t know about the additional benefits. They also get a lot of beef scrap and organ meat, from home-raised cattle slaughtered at our local custom locker, but I don’t have reliable information on the grass/corn ratio for those cows. (Given how fatty the carcasses can be, I think they get a lot of grain on average.)

    Anyway, they get 2-3 capsules a day, depending on size. I am also curious about vitamin E supplementation. Should I be adding that?

  8. Hi Elizabeth,

    I am unaware of any downside to using fish oil products made for human consumption. So pleased to hear that fish oil has provided benefit for your Labbie’s arthritis.

  9. I have been using it with GREAT results for my 12yr old Labrador with arthritis. I have been able to completly stop her metacam. It took about 4 months before I really saw a difference in her and then I slowly weaned her from the metacam and I was pleasantly surprised to see how well she did without it.

    I know the fish oil robs the body of Vit E but was wondering how big an issue that is? The fish oil I use has Vit E included so I don’t give additional Vit. E.

    Also if you are using human grade Fish Oil with with EPA, and DHA is there any reason/benefit to using Veterinary specific fish oil products?

  10. Hi Tegan,

    Great question. Most fish oil supplements contain Vitamin E which prevents the product from becoming rancid. Additionally, high quality, balanced diets should contain ample Vitamin E. I am always a bit reluctant to recommend Vitamin E supplementation (other than for specific Vitamin E responsive diseases) because, as a fat soluble vitamin, any excess cannot be excreted from the body. This is unlike Vitamin C, a water soluble vitamin, the excess of which is readily eliminated in the urine.

  11. Great question Tegan. Most fish oil supplements contain vitamin E to prevent the fish oil from becoming rancid. Additionally, if your dog is eating a high quality diet, it should contain plenty of Vitamin E. I am always concerned about supplementing fat soluble vitamins such as vitamin E because the body is unable to get rid of any excess (unlike vitamin C which is water soluble- any excess is eliminated in the urine). So, assuming you are feeding a well balanced, high quality diet, vitamin E should not be an issue.

  12. I have heard that dogs who are on fish oil also need to be supplemented with Vitamin E. Is this true?

  13. I’m using fish oil with an Aussie X who came with a history of skin problems, previously he was shaved each summer. So far, fingers crossed, this is the second summer and he has no issues. Of course, he also has flea/tick meds now, but I think the fish oil is the frosting on this cupcake.

  14. I’ve been feeding my eldest dog fish oil capsules for years. Joint health was the initial reasoning behind it and at one point he was getting six per day (80 lb Lab/Shepherd). These days he gets three per day and my border collie gets two. My little dog can’t handle the size of the capsules so I don’t bother for him.

  15. I recently had a dog come into rescue, noticed that she wasn’t seeing well in low light and she was diagnosed with PRA. The veterinary opthomologist recommended fish oil. It wouldn’t stop the progression of the disease but there had been some indications that it could slow the vision loss.

  16. Hi Carolyn,

    No need to give fish oil to an overtly healthy young dog. Enjoy that youngster of yours!

  17. I gave fish oil to my elderly dog suffering congestive heart failure and arthritis. I like to think it helped her. Now I have a new young dog — is fish oil recommended for your adult dogs with no discernible health issues?

  18. I have been adding fish oil to my dogs raw food diet for the past almost 20 yrs now. My dogs have all lived to be 14 yrs and older. The whole raw diet started for me w/ a dog who had severe skin problems. Within a week of the raw diet and oils, her skin cleared up. As a result I’ve been feeding raw ever since.

    Thanks for this post.

    jill breitner
    aka: Shewhisperer

  19. I used to feed my dog fish oil and I noticed a marked difference in her skin and coat within a couple weeks. I stopped feeding it when I switched her to dog food with fish-based protein (Wellness) for her gluten allergy (all skin conditions and GI issues solved, yay)! I know fish oil isn’t water soluble like some other vitamins and supplements, and it is possible to overdose. Should I still be feeding her fish oil, or is the DHA and EPA content in the kibble sufficient?

  20. I have included fish oil in our dogs’ food ever since we started feeding a raw diet in 1998. My dogs are incredibly healthy, live very long lives, and we seldom see our vet. Annual check ups, spay neuter surgeries, and an occasional other need. Their teeth never ever need cleaning.

    So I cannot point to fish oil and say that it has done any particular thing. It is part of their overall diet. We use salmon oil. The dogs are standard size Airedales and they get about a teaspoon a day.

  21. We had a team member pass, recently, old age.

    Before he left he would have mild to moderate seizures.

    Gave him human grade fish oil, that I take and the seizures nearly stopped, very minimal. Of course, not the same for all dogs.

    Grain free food and fish oil, well know we;re talking. As a part time pet food educator, giving supplements to counteract the food ingredients is counter productive.

  22. The cheapest fish oil capsules I have found are from Costco and Aldi. I give the dogs two a day. I feed it because Steve Brown thinks proper fats are the next frontier in pet health.

  23. Yeah, I have been following the research regarding omega-3, very interesting. Yes, Jasmine is on fish oil supplement.