Dog digestion starts at the mouth. The teeth that are useful for ripping an animal apart and cutting the tissue off are longer and sharper than the equivalent teeth in our mouths. Our back teeth (molars) are flatter and more useful for grinding foods into powder. Dogs’ habits of eating consist of tearing their food apart, cutting off pieces with the back teeth, and gulping them with only sufficient chewing to make them small enough to swallow.
The next difference is in the saliva. Dogs, on the other hand, have very little of that starch-digesting enzyme, ptyalin. It was this discovery years ago that caused people studying dogs’ eating habits to say that they couldn’t digest starch. Probably these people never saw a human wash down a huge mouthful of a doughnut with a gulp of coffee – and stopped to think that too is digested.
Our pets’ stomachs secrete somewhat stronger juice than ours. For example, a bone ingested into a healthy dog’s stomach becomes soft and pliable in less than an hour. This bone is acted upon by this stronger juice which is rich in hydrochloric acid and pepsin, and it dissolves in the stomach. The same thing might happen in the human stomach, but it would take much longer. Upon leaving the stomach the food in a dog is mixed with the same kind of juices – pancreatic enzyme and bile – which affect our food. Here, then, is where most of the digestion of starch takes place.
The human who washes down the half-chewed doughnut and the dog who gulps its starchy meal both live and thrive because digestion takes place in the small intestine. When the pancreatic enzyme (amylase)works on these starches in our case, they are so fine that the enzyme has little trouble breaking them down. In the dog, when starchy foods are fed in too large lumps, the enzyme cannot do its work effectively. To some degree the same thing happens in the human digestive tract if a person fails to chew a nut or a kernel of sweet corn – neither is digested any more than it would be by a dog.
Occasionally a dog will regurgitate any such indigestible material but inure often it will not. In feeding dogs, it has been found that it indeed pays to feed either very finely ground raw starch or precooked starches. Cornmeal fed raw is an inefficient food, but cornmeal that has been boiled until the starch granules have been cracked open so that they are vulnerable to the attack of the amylase is efficient if incomplete food. Another point of difference between dog owners and their dogs is the length of the small intestine. Food travels through it more quickly in dogs and there is less time for absorption – another reason for feeding easily digested foods. Cereals, vegetables, and fruits should be cooked to facilitate digestion. Meats are digested as easily as raw.
Now, certain known requirements must be met in the diet of every dog of every breed. These are the essentials without which our pets develop nutritional deficiencies. First of all, a dog must have enough food. This is another way of saying that there must be sufficient food to furnish energy for daily life. We measure this energy in the food by burning it in a device called a calorimeter to see how many heat units it holds. The heat units are called calories. It is knowing how many calories any resting animal of a given size requires.
An animal needs more, of course, as it exercises or works more. Living, exercise, or work all require energy, and this energy is extracted from food. If a dog gets too few calories it will live on its fat; in other words, it’ll get thin. If it gets too many, it may discard the must be cautious. Some very fat dogs become so inactive that their hearts cannot stand exercise. Their spirits are willing, but their hearts may be weak, their muscles flabby, and their lung capacity greatly reduced. In cases like this gradual daily increase in the pets’ activity is important.
Thyroid extract, which causes a dog to burn up its food and fat more rapidly, should be used with great care, if at all. Owners have been known to kill their pets by giving human doses of thyroid extract. Drugs are not necessary if common sense and willpower are used. Some people find it easier to pamper a dog by overfeeding it than to take care of its health by regulating its diet. This may be easier for a time, but only for a time. The wise owner knows that obesity is dangerous to the dog and that in the long run firmness in matters of diet is perhaps the greatest kindness he or she can show the pet.
See more: Dog Digestive System