Speaking of salmon oil, why limit it to dogs? Humans should probably be considering taking fish oil too, for its omega-3 fatty acid content. Doesn't do anything for your coronary arteries, by the way; doesn't prevent heart attacks or strokes; isn't much good for anything healthwise except keeping folks from dropping dead. Assuming you think that's a good thing.

(Really. Cuts the sudden-cardiac-death rate by about a third.)

Better than Vitamin E; it actually does something for you. Better than CoEnzyme Q-10; much cheaper, and does something good. (There are no large peer-reviewed studies about Q-10 because the smaller pilot studies showed that the promise of its anti-oxidant properties in-vitro failed to transfer to live humans..) refer to the Harvard Heart Letter, Feb 1992 or so I think