As with many things, there is no one-size-fits-all answer to this question. Your pet is an individual, and when making a decision about what type of diet to feed, you need to consider, among other things, your pet's age, size, breed, and any existing medical problems. And of course, you also need to consider the nutrient content of the diet you feed. We always recommend feeding a premium-quality diet that meets AAFCO (Association of American Feed Control) guidelines for the lifestage of the dog. We prefer a diet with meat as the first or second ingredient listed, and without any artificial preservatives or colors.
Generally, we do not recommend the semi-moist types of food, because they tend to be quite high in salt and sugar. Cats and dogs do not need this much salt and sugar in their diet. In addition, sticky, sugary foods can contribute to dental disease.
While dental caries (cavities) is related in people to the amount of sugar in the diet, dental caries is infrequent in dogs and unusual in cats. Tooth loss in both cats and dogs is much more commonly associated with gingivitis and periodontal disease, where inflammation and infection of the gum tissue causes loosening and retraction of the gum tissue around the tooth, which eventually leads to tooth loss. Sticky, sugary foods can contribute to the development of gingivitis and periodontal disease. In general, we recommend a premium-quality dry or canned food.
For large-breed dogs, most people choose a dry food, for several reasons. Larger breed dogs require a larger amount of food than smaller dogs, and dry food is easy to transport, store and prepare. Because canned food contains a much larger percentage of water (usually 80-85%) than dry foods (usually 10% or less), dry food is usually more economical to feed on a per-serving basis, especially when feeding a premium-quality food.
Many people also choose to feed their pets dry food in the belief that dry kibble has a significant scraping or wiping action on the teeth and will slow the accumulation of plaque and tartar. Dry food does exercise the mouth during chewing. However, the average dry kibble actually does not provide very much scraping action. When the tip of a tooth comes into contact with regular dry kibble, the kibble shatters before the tooth can penetrate far enough into it for any scraping to take place. There are specially designed dental diets on the market, with a kibble designed to hold together longer, allowing more tooth contact before the kibble breaks apart. This does allow for more of a wiping effect on the tooth, but even these diets are not a replacement for good dental care. While canned foods may promote somewhat faster accumulation of plaque and tartar, plaque and tartar will still eventually accumulate no matter what type of food is fed. Regular home care, yearly dental exams, and professional cleanings as needed will still be essential for optimum dental health.
Smaller breeds of dogs obviously eat less than larger dogs, and so canned foods may be more of an option cost-wise here. However, smaller breed dogs often have more crowded teeth, providing areas where plaque and tartar easily accumulate. Sometimes owners tell us that their dog is used to canned food, and refuses to eat dry food. These dogs can still be fed canned food, but home care needs to be especially emphasized, and these dogs are likely to need a yearly professional cleaning.
Until recently, dry food was usually recommended most often for cats, also. However, recent research in feline nutrition is causing some re-thinking in this area. The typical dry cat food is quite high in carbohydrates (often 45% or more) and there is some indication that this may pre-dispose certain cats to becoming overweight and possibly developing diabetes as they get older. The typical diet of cats in the wild (which usually is mostly mice and other small rodents) is thought to be about 45% protein, 45% fat, and only 4-5% carbohydrates. Dry pet food requires a fairly high carbohydrate content in order for the kibble pieces to stick together. However, canned food is typically much lower in carbohydrate content (about 10%). Some veterinary nutritionists are recommending that cats, especially those with a tendency toward obesity, be fed a canned diet with a protein, fat, and carbohydrate content as close as possible to a 'wild' diet. Interestingly, early reports seem to indicate that a canned diet does not seem to increase dental disease in these cats. More research is needed, but this is a very interesting finding.
It is important to note that specific health conditions may affect the type of diet that is recommended for your animal. For example, cats with urinary tract problems or animals with kidney disease may benefit from increased water in their diet, and feeding canned food can help with this. Always consult with your veterinarian before making any changes to your pet's diet.