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Food, Health, and Eco-news
Aggressive Dogs Lack Omega-3s; Heart-Sick Dogs Helped by Fish Oil

Italian study finds low omega-3 and cholesterol levels in angry fidos; Earlier US study found that omega-3s may help dogs with heart failure

by Craig Weatherby

There's good evidence that people with aggression and impulse-control problems tend to be deficient in omega-3s, based on studies in prisoners and mental patients.

But who would have guessed that the problem might extend to our canine companions?

Healthier Dog Food

We recently spoke with our customer and friend, Leilani Laca, founder of the Tazzy Animal Rescue Fund in Burbank, California.

Leilani informed us that she knows many people who purchase Vital Choice No Salt Added canned Sockeye Salmon for their four-legged family members, especially since the extensive pet food recalls in recent months. To visit Leilani's website, click here.

Veterinarians at Italy's University of Pavia wondered whether there might be a biochemical or nutritional basis for aggression in dogs, which they say is one of the most common problems reported by dog owners.

To find out, they studied 18 adult male German Shepherds (average age five years), who were very aggressive but showed no other health problems.

As controls, they studied 18 healthy male dogs with no history of aggression.

The vets tested the dogs' blood levels of fatty acids, including omega-3s.

They found that, compared to normal dogs, aggressive dogs had lower levels of omega-3 DHA, which is critical to brain cell membrane function. DHA deficiency is associated with depression and aggression in humans.

Interestingly, the aggressive German Shepherds also had higher omega6/omega-3 ratios, which are also associated with depression and aggression in humans.

Finally, the “bad” dogs had lower cholesterol levels, compared to their normally behaving counterparts.

As the Italians wrote, “Altogether, our results suggest that low [levels of] omega-3 fatty acids may adversely impact behavior in dogs, resulting in greater propensity to aggression.”

Because of its design, the study could not prove a causal relationship between low omega-3s and canine aggressiveness.

But, as the vets suggested, the results encourage rigorous clinical testing of supplemental omega-3s in aggressive dogs.

Omega-3s May Aid Dogs' Hearts

While researching this story, we came across a study from 1998, which showed that supplemental fish oil can improve several markers of heart health in dogs.

They enrolled 28 dogs with congestive heart failure and 5 healthy control dogs, and measured the canines' levels of key inflammatory chemicals associated with heart disease.

At the outset, the heart-sick dogs had lower blood levels of omega-3s and omega-6s (While high omega-6/omega-3 ratios are not healthful, small amounts of omega-6s are needed for optimal heart function).

The dogs with heart failure were divided into two groups, which received either fish oil or placebo pills for two months.

At the end of the study, the fish oil group showed lower levels of a key inflammatory marker (IL-1) and improved appetite, weight gain, and heart function, compared to the placebo group (Freeman LM et al 1998).

It appears that canines' cardiac health can benefit from fish. Just be sure the fish is boneless, or give your pooch low-sodium canned Salmon with soft, edible bones.


  • Re S, Zanoletti M, Emanuele E. Aggressive dogs are characterized by low omega-3 polyunsaturated fatty acid status. Vet Res Commun. 2007 Sep 19; [Epub ahead of print]
  • Freeman LM, Rush JE, Kehayias JJ, Ross JN Jr, Meydani SN, Brown DJ, Dolnikowski GG, Marmor BN, White ME, Dinarello CA, Roubenoff R. Nutritional alterations and the effect of fish oil supplementation in dogs with heart failure. J Vet Intern Med. 1998 Nov-Dec;12(6):440-8.