In dogs, some evidence exists for supplementing in heart/skin/kidney/inflammatory and auto-immune joint disease, and in hyperlipidemia (not high blood cholesterol). Additional areas being researched right now for the use of omega-3 in dogs are: cognitive function disorders, IBD (inflammatory bowel disease) and cancer.
In dogs, the NRC (National Research Council) recommended allowance dose of omega-3 has been set, as well as a safe upper dose limit (over 10 times the recommended allowance). From the research done, doses for different disease process have been calculated, and are in excess of the recommended NRC daily dose. Actually, most people would be surprised at how large the doses are. The maximum safe dose of omega-3 has not been established in cats, and large doses in kitties need to be supervised by your veterinarian. In cats, you need to weight the risk of immunosuppression vs the benefit of the anti-inflammatory effect.
If you wish to add fish oils to a diet already containing omega-3, it is important to bring the ingredient list with the guaranteed analysis to your veterinarian. Some diets do not include the amount of omega-3, and you might need to contact the manufacturer to get the information. When diets have some omega-3 included, it is important to calculate how much your pet is already receiving, so we can figure how much omega-3 need to be supplemented to the existing diet. Of great importance too is the exact amounts of all the different omega-3 parts, since in fish oils, these are present: EPA, DHA, ALA and other probably minor omega-3. ALA (α-Linoleic Acid) also comes from flax, corn, canola and soybean oil. However, the amount of conversion of ALA to EPA and DHA is usually very low, with flax seed having the best conversion. It can take 2.3 times more flax seed oil to have the same effect than fish oil.
Too much might be detrimental; they also add calories and fat to digest. I always recommended to start with a low dose as some dogs and cats cannot tolerate fish oils.
This is only a small window into fish oil supplementation in dogs and cats. They are a great adjunct in certain disease process; however they are not for all dogs and cats. Consult your veterinarian to know which dose is best suited for your dog or cat’s condition.
References:“Therapeutic use of fish oils in companion animals”, JAVMA, Vol 239, No.11, December 1, 2011, p.1441-1451