Raw versus Cooked Dog Food
One of the hot debates in the dog food world is whether food should be fed raw, or should be fed cooked. There are strong arguments on both side.
As part of this debate, one should consider each of the common foods (meat and bones, fruit and vegetables, grains) separately as the arguments for each vary.
Meat and Bones
In general, I disagree with feeding cooked bones to dogs. To begin with, cooking bones makes them more brittle, increasing the chance of the bones splintering and causing internal injury to the dog. Furthermore, cooking the bone is likely to remove a number of the beneficial nutrients. For more information, click on feeding bones.
The debate over raw meat is less clear. Cooking meat changes it chemically, destroying a number of enzymes and amino acids. In particular, cooking meat destroys most of the essential amino acid Taurine. One research report indicates that two thirds of this essential nutrient is destroyed when baking beef and almost 90% when boiling it. This can lead to various illnesses (including the heart disease 'Dilated Cardiomyopathy') unless the diet contains an additional source of this nutrient. Other nutrients are also changed (or destroyed) by cooking, but less information is available on them than on Taurine.
Cooking also destroys a number of enzymes in the meat. Proponents of raw feeding argue that this makes the meat more difficult to digest and reduces the nutritional values. Opponents argue that these enzymes are not required by dogs. More research into this point is required to settle this debate.
Opponents of raw feeding point out that cooking partly breaks down the complex structures in meat, making it easier to digest. Certainly it is true that humans find cooked meat much easier to digest than raw. However, given that dogs have a different digestive system (in particular, much stronger stomach acids), more research would be required to determine the extent to which cooking aids or hinders meat digestion in dogs.
Another consideration is the possible infection of dogs by bacteria and parasites found in raw meat. Certainly it is true that feeding of raw meat has resulted in a number of dogs becoming ill (in some cases seriously ill). The probability of this happening is related both to the type of meat (pork being more dangerous than beef) and to the source of meat (meat from wild animals is much more likely to be infected with parasites than human-grade meat from the local store).
If you are feeding raw meat to your dog, it is wise to take the same care as you would with your own meat. The meat should be kept in a refrigerator (for a short time) or a freezer, rather than left outside in the heat for long periods of time. The meat should be human grade and raw pork should be avoided.
Fruit and Vegetables
Most ripe fruits are relatively easy to digest without cooking. However, the digestive system of dogs is not suited to raw vegetables. To begin with dogs have carnivore teeth, which can tear meat but are not suited to grinding food into small pieces which are easily digested (herbivore teeth are very good are grinding food). Secondly, dogs have a short digestive system, which is not suited to breaking down vegetables. In addition, dogs lack digestive enzymes in their saliva. Consequently, raw vegetables tend to simply pass through the dog's digestive system, with much of the nutrients not being absorbed.
Cooking vegetables offers two advantages. The first is that it is more easily digested, so more of the nutrients are available to the dog. Secondly, because more of the food is digested, there is less wastage, which means lower food costs.
An alternative to cooking is to puree the vegetables (cutting or grating is not sufficient). This breaks down the vegetables, making them much more digestible. Freezing the vegetables will to a lesser extent also break down the vegetables, making them more digestible.
The digestive system of dogs (and humans) is not suited to uncooked grains. In general, grains must be well cooked in order for a dog to get much nutritional value from them.