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EPA + DHA (Long-chain Omega-3 fatty acids) in dog and cat diets

A short guide to the role of EPA + DHA (Long-chain Omega-3 fatty acids) in dog and cat nutrition.

EPA + DHA (Long-chain Omega-3 fatty acids)

EPA (eicosapentaenoic acid) is one of the strongest natural anti-inflammatory factors — it modulates the production of prostaglandins and leukotrienes, "extinguishing" inflammation in the joints, gut, kidneys and skin [1]. DHA (docosahexaenoic acid), in turn, is the main building block of the brain and the retina of the eye, key for the nervous system and vision — especially in the young and in females during pregnancy [2]. Both are extremely susceptible to oxidation (rancidity), which is why fish oil supplementation must always go hand in hand with an appropriate dose of vitamin E (unless the manufacturer has already added it to the bottle).

This is one of the most important nutrients to keep an eye on in BARF: the meat of land animals is flooded with omega-6 (an omega-6:omega-3 ratio on the order of 10:1–20:1), and has practically none of the long-chain omega-3. A diet without a sensible source of EPA+DHA is therefore chronically tilted pro-inflammatory, even if the animal looks healthy — the damage accumulates over years [3].

Where it's found: Small fatty sea fish (sardines, sprats, herring, Atlantic mackerel) served raw and whole 2–3 times a week — the best choice, because they have low thiaminase activity and also contribute protein, iodine, selenium and vitamin D. Next, fish oil from fish meat (preferably from sardines or anchovies, in triglyceride form), oil from sea algae (Schizochytrium — a rescue in case of fish allergy, rich in DHA) and krill oil. Cod liver oil is NOT a good source of EPA+DHA — it contains too much vitamin A and D to use as a tool for topping up omega-3.

Deficiency: Developmental disorders in puppies/kittens (brain, retina), aggravation of allergies, atopic dermatitis, a dull dry coat and painful joint degeneration [1] [4]. In cats there is additionally a deterioration of kidney function (and chronic kidney disease is the most common cause of death in older cats) and a tendency to IBD.

Excess: At extreme doses (a multiple of the norm) EPA and DHA inhibit platelet aggregation and prolong clotting time — it is worth discontinuing the oils a few days before planned procedures (neutering, spaying). Too large a single dose causes fatty diarrhea. At normal dietary doses an overdose is very difficult; a more realistic problem is lipid peroxidation in the absence of vitamin E [5].

Species difference

Vegetable oils (linseed, hemp) contain ALA — plant omega-3. Dogs convert ALA to EPA/DHA very poorly (below 5–10%), and cats in practice not at all, because they have almost zero delta-6-desaturase activity [3]. That is why linseed oil is not a substitute for fish oil, and for a cat vegetable oils as a source of omega-3 are completely worthless — carnivores must receive EPA/DHA exclusively from marine sources.

In cats there is an additional risk: an excess of unsaturated fats without vitamin E leads to pansteatitis (inflammation of the fatty tissue), classically in cats fed mainly tuna. Tuna should not be the base of the diet — it accumulates heavy metals and threatens pansteatitis. Fish is to be a tool for delivering EPA+DHA, not a daily main component [5].

What to watch for

Always supplement vitamin E with long-term administration of fish oils. Fatty fish brings a lot of vitamin D — keep an eye on the total supply, especially if you are simultaneously using cod liver oil or a separate vitamin D supplement. Just as important as raising omega-3 is limiting the excess of omega-6 (chicken skin, poultry fat) — fish oil alone will not fix a diet flooded with poultry fat [3]. Regularity is more important than one-off large doses — saturating the cell membranes requires 8–12 weeks of steady supply. Store fish oil in the refrigerator; if it has a sharp, unpleasant smell — throw it out.

Standards

NRC 2006: dog RA = 0.11 g/1000 kcal ME, SUL = 2.8 g/1000 kcal; cat RA = 0.025 g/1000 kcal ME (a lower minimum than in the dog, but the clinical requirement is higher due to the lack of conversion) [6].

Sources

  1. Bauer JE (2011). Therapeutic use of fish oils in companion animals. JAVMA 239(11):1441-1451. https://doi.org/10.2460/javma.239.11.1441
  2. Zicker SC, Jewell DE, Yamka RM, Buber NA (2012). Evaluation of cognitive learning, memory, psychomotor, immunologic, and retinal functions in healthy puppies fed DHA-rich fish oil. JAVMA 241(5):583-594. https://doi.org/10.2460/javma.241.5.583
  3. Bauer JE (2016). The essential nature of dietary omega-3 fatty acids in dogs. JAVMA 249(11):1267-1272. https://doi.org/10.2460/javma.249.11.1267
  4. Roush JK, Dodd CE, Fritsch DA et al. (2010). Multicenter veterinary practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs. JAVMA 236(1):59-66. https://doi.org/10.2460/javma.236.1.59
  5. Lenox CE, Bauer JE (2013). Potential adverse effects of omega-3 fatty acids in dogs and cats. J Vet Intern Med 27(2):217-226. https://doi.org/10.1111/jvim.12033
  6. National Research Council (NRC) (2006). Nutrient Requirements of Dogs and Cats. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats