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Fish oil. Ewww. Sounds super unappealing, right? At least it does to most of us who grew up in the U.S.!  

But we’ve all heard the buzz from health advocates that fish oil taken by mouth is practically a miracle food for humans and dogs. As a veterinarian, I often recommend fish oil for dogs with allergies. 

Fish oil contains an unusually high level of omega-3 fatty acids. Omega-3 fatty acids act as an anti-inflammatory in dogs with skin allergies. And there is a respectable amount of scientific evidence to support the use of fish oil for multiple health conditions in dogs.  

How much fish oil do you need to give to a dog suffering from allergies? You can skip down the article to take a look at the dosage tables I’ve compiled from authoritative sources.

If you believe your dog has a severe inflammatory condition that might respond to fish oil, please get help from your veterinarian. Fish oil can cause side effects at high doses so it’s best to use those only under professional supervision. 

Because it is made and labeled specifically for pets, I recommend Nordic Naturals Omega-3 Pet products.

dog with severe skin allergies
This allergic dog could use some fish oil!

Omega-3 Fatty Acids for Skin Allergy in Dogs

Canine atopic dermatitis is common in dogs. Symptoms of skin allergies include hair loss, sores and scabs, increase scratching, red skin, bad body odor and poor quality of life for affected dogs.

Dogs with allergies develop dry skin resulting from a decreased amount of fat in the outer layer of their skin. Disruption of the outer skin barrier allows allergens to contact the immune system in the deeper layers of the dog’s skin. A 2011 study found that oral administration of omega-3 fatty acids increased the amount of fat in the outer skin layer of allergic dogs. (8) 

Fish oil supplementation may allow an allergic dog to take lower doses of their other meds (like steroids or oclacitinib). 

Researchers in a 2004 study gave either borage seed oil, fish oil or a placebo to 60 dogs over a 12-week period. All of the dogs were also treated with prednisolone (steroid) to control their allergy symptoms. After about nine weeks, the dogs taking fish oil were able to take a lower dosage of prednisone to control their pruritus (itching). (6)

Steroids are great when your dog is in a desperate situation, but they have so many side effects that veterinarians try not to use them long-term whenever possible. 

The fact that a fatty acid supplement can reduce the amount of steroid meds needed to control allergy symptoms is pretty amazing!

liquid fish oil
Mmmm… delicious fish oil!

What Are Essential Fatty Acids?

Dogs need to consume certain fats in their diet in order to survive. These are called essential fatty acids (EFA’s), meaning the animal can’t manufacture these compounds in adequate amounts from other materials. EFA’s must come from their diet.

Dogs have five EFA’s they must obtain from food (7):

  • Linoleic acid (LA, omega 6)
  • Alpha-linolenic acid (ALA, omega-3)
  • Arachidonic acid (AA, omega 6)
  • Eicosapentaenoic acid (EPA, omega-3)
  • Docosahexaenoic acid (DHA, omega-3)

The term “omega” is a description of the fatty acid’s structure and not really necessary to understand for this discussion. You just need to understand that omega 6’s are different from ’s but they’re both important.

A dog’s body works best when he consumes a particular ratio of omega-6 to omega-3 EFAs. An excess of either one can cause health problems.

Scientists believe an optimum ratio of omega-6 to omega-3 is somewhere between 5:1 and 10:1.

Different Omegas Have Different Functions in the Body

Omega 6 fatty acids come from grains, vegetable oils, nuts, seeds, poultry, and eggs. Omega 6 fatty acids promote inflammation, which sounds bad, but inflammation is necessary for healing the body. Dogs need omega-6 EFAs to heal properly. But when there’s an excess of omega 6, there will be excess inflammation.

Omega-3 fatty acids have an anti-inflammatory effect on your dog’s body. They are found in high concentrations in fish and in lesser amounts in nuts and seeds. 

Dogs need to consume enough omega-3 fatty acids to balance out the omega-6 fatty acids present in their regular diet.

Chihuahua with facial hair loss and red skin
Fish oil can help dogs with itchy skin like this poor little guy.

Benefits of Higher Omega-3 Intake

Omega-3 fatty acids added to your pet’s diet can decrease inflammation. Scientific research supports the use of an omega-3 supplement for several canine diseases, including

  • Osteoarthritis (2) 
  • Itchy skin symptoms from allergies (4)
  • Aging changes (3)
  • Aggression (9)

Feed Whole Foods Containing Omega-3 FAs

It’s possible to increase your dog’s omega-3 fatty acid intake by feeding whole foods that are rich in the substance. The caveat is that you risk giving your dog too many calories or causing digestive upset with fatty foods he’s not used to.

Cold-water, fatty fish are high in omega-3 and low in omega-6 fats. You can also consult this list of other foods with lower omega-6: omega-3 ratios

Canned salmon and water-packed canned sardines are convenient and affordable options. They are whole foods with high omega-3 fatty acid content.

canned salmon
  • 3 ounces of canned pink salmon (with skin and bones) contains about 718 mg of EPA and 685 mg of DHA (a total of 1403 mg of omega-3 FAs ).
  • 3.2 ounces of canned sardines contain 430 mg of EPA and 460 mg of DHA (a total of 890 mg of omega-3 FAs ).

A 10-pound dog could benefit from eating half an ounce of salmon or sardines a few times a month. Start with small quantities given infrequently to avoid causing stomach upset.

Commercial Dog Food with High Levels of omega-3 Fatty Acids 

The most convenient way to improve your dog’s intake of omega-3 fatty acids is to simply switch your dog’s diet to commercial dog food with an increased level of the nutrient.

There are several high-quality, nutritionally balanced products with higher levels of omega-3 fatty acids. These foods are adequate s to promote general health as well as quell mild to moderate inflammation.

Dogs with severe inflammation probably need more omega-3’s than what is contained in these special dog foods. Ask your vet for a recommendation.

Omega-3 Fatty Acid Supplements

Salmon oil, krill oil, cod liver oil, flaxseed oil, hemp seeds, chia seeds… All have omega-3 fatty acids but they’re not all equal. What’s the difference?

Salmon and krill oil are similar to regular fish oil and may contain an even higher concentration of EPA+DHA. These are both good options but may be more expensive and less environmentally friendly.

Cod liver oil is not the same as fish oil because it contains significant quantities of vitamins A and D. Dogs can overdose on these vitamins if you give them too much. My advice is to stay away from it

Flaxseed oil, hemp oil, hemp seeds, chia seeds, etc. are plant-based sources of omega-3 and are not the same thing as fish oil. Dogs don’t absorb the ALA present in plant-based foods as well as the EPA and DHA from fish oil. One notable exception to this is algae oil. Algae oil is a plant-sourced product that contains EPA and DHA, but there is little information about its safety or efficacy when fed to dogs.

Golden Retreiver

What is Fish Oil?

Fish oil is an oral nutritional supplement made by extracting and purifying the oil from fatty fish. 

Sardines, herring, mackerel, anchovies, and salmon are used to make fish oil. High-quality fish oil is a fresh, concentrated source of omega-3 fatty acids. It contains the two key omega-3’s dogs need: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Fish oil is available in liquid, capsule or tablet form. You’ll find many different products at pet supply, grocery, and online stores. 

But not every fish oil product is worth buying.

How to Choose a Good Fish Oil for Your Allergic Dog

The “International Fish Oil Standards Program” or IFOS is an independent group that tests and certifies fish oils. 

IFOS has a website that lists the fish oil products they’ve certified. The IFOS certification on a product label verifies a product’s purity, potency, and freshness.

And here’s another news flash: fish oil should not smell horribly fishy. If yours does, it may be rancid (spoiled) and should not be used.

I’ve found that higher-quality products like Nordic Naturals and Carlson’s don’t have a strong fishy odor or flavor. 

Buy only the amount of fish oil you’ll use in a month and store it in the refrigerator to keep it fresh longer.

Read the Label to Find EPA+DHA in Milligrams

The label on fish oil supplements lists both the total amount of omega-3 fatty acids and the amount of EPA and DHA the product contains. 

The important number is the sum of the EPA and DHA in milligrams (mg). Each product has different amounts, so check the label to determine the right amount to give your pet. 

Also, check for the “IFOS” logo as well as the product expiration date.

Fish Oil Dosage for Healthy Dogs

The National Research Council (NRC) is an organization of scientists who provide guidelines on the nutritional requirements of dogs. The NRC recommended allowance for general health is only 30 mg EPA+DHA per metabolic body weight for dogs (7).

I’ve calculated the amount recommended by researchers and veterinary nutritionists for different sizes of dogs in Table 1 below. This dosage is great for dogs who are already pretty healthy but you want to give them a little extra boost.

[See Table 2 below for the dosage recommended for dogs with allergies.]

Table 1: Fish Oil Daily Dosage Chart for Healthy Dogs (7)

Body Weight in PoundsEPA+DHA in mg

Fish Oil Dosage for Dogs with Allergies

The perfect amount of omega-3 fatty acids for dogs with skin allergies is not known. Super-high doses have been used by veterinarians to treat severe inflammatory diseases.  

The dose recommended by researchers and veterinary dermatologists for dogs with allergies is approximately 25 mg of EPA+DHA per pound of body weight once a day. It may take a couple of months before you see a noticeable improvement in an itchy skin condition. See Table 2 below.

Remember to use the sum of EPA+DHA in milligrams (not the milligrams of “total omega-3’s”) to calculate the dose.

Table 2: Fish Oil Daily Dosage Chart for Dogs with Allergies (1)

Body Weight in PoundsEPA+DHA in mg

Table 2 dosages are about the same as recommended on the Nordic Naturals Omega-Pet label. Before trying higher doses of omega-3’s, consult your veterinarian to determine a safe dosage.  

Use caution when giving any oil or fat to animals who are prone to bouts of pancreatitis.

If your dog has a sensitive stomach, start with 50% of the dose from the table for two weeks and stop if you notice diarrhea or an upset stomach. A high-quality, fresh, refrigerated product should help minimize potential side effects.

Results Are Not Immediate

Keep in mind that you might not see the full effect of giving your dog more omega-3 fatty acids for a couple of months. It takes time for them to build up in a dog’s body. If you give the amount recommended every day,  you should see some positive changes within 60 days. 

Most people give their dog a fish oil supplement long-term as long as they don’t notice weight gain, digestive upset or other adverse symptoms.

Don’t Go Overboard! Side Effects from Too Much Fish Oil 

Most animals do great with conservative dosages of fish oil. But more is not always better. Overuse of fish oil can cause serious harm to your pet.

According to a paper published in the Journal of Veterinary Internal Medicine (5), excessive doses of fish oil can cause:

  • Abnormal platelet function
  • Gastrointestinal symptoms
  • Decreased wound healing
  • Damage to lipids (fats) in cells of the body
  • Oversupply of nutrients and potential toxin exposure
  • Weight gain
  • Changes in immune system function
  • Changes in blood sugar regulation
  • Alteration of drug metabolism

Vet-Recommended Fish Oil Supplements

I recommend Nordic Naturals Omega-3 Pet. It is labeled specifically for dogs and doesn’t have any flavoring as many human-targeted fish oil products do. 

Although many of Nordic Naturals’ products have no IFOS rating, you can find extensive safety testing information on the company’s website for each batch of fish oil they produce.

The label-recommended dosage on Nordic Naturals  Pet products is between an anti-inflammatory and nutritional dosage. Most dogs should tolerate this moderate dosage, but it’s still a good idea to introduce it gradually.

To avoid the stress of pill administration, buy liquid fish oil and mix it with your dog’s food. Most dogs like the taste.

Nordic Naturals Omega-3 Pet is high quality and inspected to ensure purity. It’s even available in a 2-ounce container for small dogs so it won’t go rancid before you use it all.

Store your fish oil in the refrigerator to maintain freshness!

Related Products to Avoid

  • Oils with vitamin D or other compounds added. 
  • “Burpless” capsules. Your pets don’t need them and since they’re made for human stomachs, they may not dissolve in a dog’s stomach.
  • Cod liver oil. It’s different than regular fish oil and should not be used as a substitute.
  • Plant-sourced omega-3 supplements. Pets can’t absorb these the way humans can. They’re not a substitute for fish oil.
  • Cheap fish oil capsules in large containers. Buy small containers and store them in the refrigerator! Use up the entire container within a couple of months, or at the latest, by the expiration date on the product label. Discard any product that has a strong fishy odor.

photo credits CC/BY 2.0: Chris Barnes, Anne Worner

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Related Posts:


  1. Bauer, J. E. (2011). Therapeutic use of fish oils in companion animals. Journal of the American Veterinary Medical Association, 239(11), 1441-1451.
  2. Fritsch, D., Allen, T. A., Dodd, C. E., Jewell, D. E., Sixby, K. A., Leventhal, P. S., & Hahn, K. A. (2010). Dose-titration effects of fish oil in osteoarthritic dogs. Journal of Veterinary Internal Medicine, 24(5), 1020-1026.
  3. Hall, J. A., & Jewell, D. E. (2012). Feeding healthy beagles medium-chain triglycerides, fish oil, and carnitine offsets age-related changes in serum fatty acids and carnitine metabolites. PLoS One, 7(11), e49510.
  4. Harvey, R. G. (1999). A blinded, placebo-controlled study of the efficacy of borage seed oil and fish oil in the management of canine atopy. The Veterinary Record, 144(15), 405.
  5. Lenox, C. E., & Bauer, J. E. (2013). Potential adverse effects of fatty acids in dogs and cats. Journal of Veterinary Internal Medicine, 27(2), 217-226.
  6. Saevik, B. K., Bergvall, K., Holm, B. R., SAIJONMAA‐KOULUMIES, L. E., HEDHAMMAR, Å., Larsen, S., & Kristensen, F. (2004). A randomized, controlled study to evaluate the steroid sparing effect of essential fatty acid supplementation in the treatment of canine atopic dermatitis. Veterinary dermatology, 15(3), 137-145.
  7. National Research Council (NRC). (2006). Nutrient requirements of dogs and cats. National Academies Press.
  8. Popa, I., Pin, D., Remoué, N., Osta, B., Callejon, S., Videmont, E., … & Haftek, M. (2011). Analysis of epidermal lipids in normal and atopic dogs, before and after administration of an oral omega 6 /omega 3 fatty acid feed supplement. A pilot study. Veterinary research communications, 35(8), 501-509.
  9. Re, S., Zanoletti, M., & Emanuele, E. (2008). Aggressive dogs are characterized by low polyunsaturated fatty acid status. Veterinary Research Communications, 32(3), 225-230.
  10. US Department of Agriculture (USDA). (2005). National Nutrient Database for Standard Reference, Release 28.


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