Use of Fish Oils as a Therapeutic/Preventive Supplement


Fish oils have better evidence in human and pet literature than practically all other supplements combined. These claims have been substantiated by good studies and put them in the lead of the evidence based supplements. The challenges are finding the correct dose and the best way to deliver it in a convenient cost effective way.

  • Decreases inflammation throughout the body at 20mg/lb EPA & 12mg/lb DHA
  • Helpful for arthritis, skin conditions, cognitive, heart & kidney disease
  • Wide concentration range between products
  • Dose is the critical issue to allow effective treatment or prevention
  • More evidence based studies than any other supplement and most new ingredient being added to pet foods

High doses are used to treat and may prevent skin conditions, heart problems, kidney disease, osteoarthritis, cancer, “inflammation associated with daily activity” and improved cognitive function.
Eicosapentanoic Acid (EPA) & Docosahexanoic Acid (DHA) or fish oils
[Also referred to as Omega 3’s, polyunsaturated fatty acids (PUFA’s) and Free Fatty Acids (FFA’s)]
20mg /lb EPA & 12mg/lb DHA per day.

Concentration varies widely among products but typical fish oil capsules contain 1000mg of oil of which 180 mg is EPA and 120 mg is DHA. (So a 60lb dog requires 7 capsules per day) Read labels closely for mg of EPA per capsule, serving size etc. Almost all label doses require doubling or tripling to reach the 20mg/lb per day. Skin inflammation can require much higher dosing.

Please use our handy Dosage Calculator, below.

Sardines, anchovies, deep ocean fish which all convert plankton a natural source of EPA.
Fish Oil has no drug interactions.

Fish Oil can cause diarrhea at higher doses (start at a lower dose and increase slowly and use newer high concentration products to prevent GI upset)

What You Need To Know


EPA (Eicosapentanoic Acid) is most active for skin, joints, and heart. DHA (Docosahexanoic
Acid) is most active for brain and retina. The combination, if given at 40mg/kg & 25mg/kg respectively has been proven to turn off inflammatory mediators that cause damage throughout the body (1).


Fish oils are highly prone to oxidation so they need to be protected from light and need adequate levels of Vitamin E or other antioxidants to preserve them.

Flax Seeds

Flax seeds (and other Omega 3 fatty acids) are NOT readily converted to active forms (EPA/DHA) in pets, therefore are probably ineffective for preventing inflammation. (They may do other good things)


There is CONSIDERABLE variability in the amount of EPA & DHA per capsule or ml in both human and pet products. Dosing is vital to achieve desired effects. (See dosing info on this page). Finding a convenient way to dose to achieve daily compliance can be a challenge!

Pet Weight

In overweight pets you need to account for additional calories (10 cal per 1 gm capsule, so this adds 70 cal to an overweight pet’s daily intake). High potency formulations can cut the calories by 2/3.

Prescription Foods

There are now 5 prescription dog foods and 2 prescription cat foods (see below) that deliver at least 20mg/lb of EPA. They range from 290 to over 600mg EPA per cup. Although “fish oil” is now the most commonly added pet food ingredient the amount of EPA per cup must be established to determine if therapeutic and to know how much to supplement.

Omega 6/3

The ratio of Omega 6 to 3 appears much less important (if at all) than previously believed.

DHA Importance

DHA may be more important in cats (bladder & joint disease), and cognitive issues in both older dogs & puppies-where it is now been proven to increase learning.


Bioavailability of triglyceride, ethyl ester and free form now being debated.

Pet Fish Oil Dosage Calculator

Suggested Fish Oil Sources

Typical Human Products:
  • Fish oil capsules. Usually 180mg of EPA per capsule (Walgreens, Costco etc).
  • High potency human products (Carlson, Nature’s Bounty & others range from 300 to 700mg EPA per capsule).
  • Liquid fish oil. Up to 180mg of EPA per ml) Need to make sure it is NOT citrus flavored, for pet taste buds!
Veterinary Products:
  • DVM Free Form Snip Tips® 515mg EPA/capsule
  • Omega AllerG3 ® 180 mg EPA/ml
  • Omega-3 Ascenta TM 148mg EPA/ml
Prescription Dog Foods:
  • Purina Prescription JM ® (290mg EPA/cup)
  • Hills Prescription J/D ® (394mg EPA/cup)
  • Royal Canin Joint Mobility (330mg EPA/cup)
  • Royal Canin Prescription Joint Mobility Large Breed (500mg EPA/cup)
  • Purina DRM ® Trout & Salmon Allergy Diet (640mg EPA/cup)
Prescription Cat Foods:
  • Hills Feline J/D (605.7mg EPA/cup 388 mg DHA/cup)
  • Royal Canine Feline Mobility JS (440mg EPA/cup 222 mg/DHA-also contains Perna green lipped mussel)

This information provided based on the scientific papers listed below as well as seminars, and evidence based sources. More information on the human nutraceutical site

Evaluation of a Therapeutic Diet for Feline Degenerative Joint Disease
  – Duncan Lascelles J Vet Intern Med 2010, 1-9

Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis
James K Rousch DVM,MS,DACVS; Alan R. Cross DVM ,MS,DACVS et al JAVMA Vol236, No.1, January 1, 2010

Freeman, Lisa OSU Waltham 2002 Nutritional Conference
 – Mueller RS, et al. J Sm An Proc 2004, 45:293-297.

Simopoulos AP. J Amer Coll Nutr 2002, 21:495-505

Bauer JE. I Am Vet Med Assoc 2006, 229:680-684.

Caterson B, et al. Hills European Symposium Genoa, Italy, Apr 2005:14-18.

Brown SA, et al. J Nutr 1998, 128:2765S-2767S. Smith CE, et al. J Vet Inter Med 2007, 21:265-273.