Recently, I read an interesting study regarding the evolutionary basis for dog and cat feeding behaviors. The author, John Bradshaw studied the physical adaptations of dogs and cats relative to their diets. Here is a summary of what he found:
1) Teeth – Cats have highly specialized teeth that are perfect for catching and eating prey. The teeth are cylindrical in nature which are good for penetration and tearing. Dogs, on the other hand, have rather generic, unspecialized teeth that can be used for a variety of functions.
2) Taste – Cats cannot taste salt or sugar which is why they tend to eat bitter tasting foods. Dogs cannot taste salt but can taste sugar which is probably why many dogs enjoy ice cream and other sweet human foods. Note, I do not recommend ice cream for dogs!
3) Feeding Behavior – In general, dogs have larger stomachs capable of holding large amounts of food. This is ideal for animals who eat infrequently such as when the pack makes a kill. Domestic cats have smaller stomachs as they tend to eat smaller, more frequent meals.
4) Nutritional Requirements – Cats need to eat animal protein to fulfill their nutritional requirements. They cannot metabolize carbohydrates into glucose for energy nor synthesize all their required amino acids from plant based proteins. Dogs, are more like humans as they can metabolize carbohydrates into glucose and metabolize plant based proteins.
So based on these results, cats really are strict carnivores who have evolved to eat a low carbohydrate diet. I now recommend canned pate food for all my feline patients. Avoid foods that contain chunks of meat with gravy because the gravy is loaded with carbohydrates.
Bradshaw, John W.S., The evolutionary basis for feeding behavior of domestic dogs (Canis familiaris) and cats (Felis catus). J. Nutri. July 2006; 136(7 Suppl): 1927S-1931S.