Veterinarians and pet owners have long advocated dry food as the best choice to promote dental health in pets. The common belief is that because kibble is hard it requires more chewing, which promotes dental health. It could be argued that these are desperate beliefs to alleviate any guilt about feeding an inexpensive, convenient diet. Simple observation of canine eating behavior would confirm little chewing of a meal. In fact the cat has anatomical limitations that prevent it from chewing. Also research does not favor dry over wet for teeth health.
The Dog’s Teeth in the Wild
As pack hunters dogs compete fiercely with each other over a carcass. They tear and gulp and dive back in for more. Taking time to chew would decrease overall food consumption, which is not an effective survival technique. The modern, domestic dog exhibits the same “grab and swallow” feeding behavior with only minor cracking of larger kibble bits. Observation of the physical form of dog vomitus confirms that little chewing occurs during eating. The vomit looks exactly like the food, only wetter.
Interestingly, studies of African wild dogs revealed these animals have significantly less dental tarter than their kibble eating domestic relatives. Yet these wild dogs suffer the same incidence of periodontal disease as domestic dogs eating commercial food. This seems to contradict the early studies in dogs and cats that suggested kibble was better than soft food for tooth health. These early studies focused on plaque and tarter accumulation rather than periodontal disease and other more serious oral problems, and inadvertently overstated the case for dry food and dental health.
Even more interesting are studies in dogs with access to bones for chewing. Despite significant protection from plaque formation and gingivitis, bone chewing does not significantly decrease the incidence of periodontitis, especially around the premolars and molars at the back of the mouth.
The Cat – At Home and in the Wild
As with the dog, anyone who has looked at their cat’s vomit knows that cats don’t chew. In fact they can’t. Felines have an anatomically fixed lower jaw. This means they have limited lateral or side-to-side movement of the jaw that is necessary to really chew. That is why kibble eating cats tilt their head and use gravity to move food to the side so it can be cracked, not chewed, by sharp teeth. The absence of flat teeth like molars and only sharp tearing teeth alone is evidence of a species that does not chew. I am amazed that years of examining the mouths of cats do not alert veterinarians to the lack of chewing capabilities of the cat.
Again studies of feral and wild cats in Africa and Australia confirm that these cats have less dental tarter than domestic cats fed canned and dry diets, yet suffer the same incidence of periodontal disease.
The Plaque Disconnect
So we have wild cats and dogs that rip and tear soft carcasses with less dental tarter than domestic cats and dogs that don’t chew their hard kibble, yet both groups exhibit the same incidence of periodontal disease. What this means is that the relationship of tarter and dental disease is still to be defined. It also means that the relationship of chewing and dental disease has yet to be defined.
This does not build a case for dry food over wet food for preventing dental disease. Dental health is far more complex than the consistency of food and chewing activity of the animal. All pets, no matter what their diet, require regular teeth brushing to prevent periodontal disease. I am sure your pet will welcome the addition of canned food to its diet.
Dr. Ken Tudor