"Although the concept of good and bad fats is appropriate for human health, dogs and cats are able to consume both types of fats in their diets without undue risk of coronary artery diseases, heart attacks, or strokes to which humans succumb. The simplified reason for this is that they have more good cholesterol (HDL) than bad cholesterol (LDL) to begin with, no matter what types of fat they consume. Second, in contrast to humans, dogs and cats typically are resistant to the development of hypercholesterolemia and atherosclerosis, even when they consume amounts of dietary fat that would typically turn human blood into sludge.

The fact that good cholesterol concentrations are higher than the concentrations of bad cholesterol is part of the mechanism that protects them from cardiac diseases that may affect humans. In addition, although saturated fats (and possibly trans fats) may cause modest increases in blood cholesterol concentrations in dogs, these dietary components do not appear to impart any increased risk of arterial diseases in dogs, which is in contrast to their effects in humans.

Thus, it is not advantageous to classify the various types of fats as good or bad in dogs or cats, although definitive data for cats (other than the fact that cats have high HDL cholesterol concentrations) have not been obtained. In view of these metabolic differences, it is proposed that the types of dietary fats for dogs and cats should be classified as functional or facilitative, rather than good or bad, respectively."

Facilitative and Functional Fats in Diets of Cats and Dogs” - Dr. John Bauer, DVM, PhD, DACVN.