Dogs derive much pleasure from gnawing bones. They have some nutritional value and are useful in helping to keep their teeth clean and their gums healthy.
Bones can cause some problems. Cooked bones tend to splinter into sharp fragments and if these are swallowed some severe complications can result. Sharp pieces irritate the lining of the stomach and small intestine and induce vomiting. If passed further down the intestinal tract, severe discomfort can result.
Usually, the bones progress through the small intestines until they reach the large bowel. The muscle contractions of the large bowel are not as rapid as in the small intestine and the contents of the large bowel are not as fluid. Here the bones tend to be concentrated into a hard mass which is difficult for the muscle wall to expel.
The lining of the rectum becomes inflamed and despite frequent and intense straining the dog cannot pass the mass through the length of the rectum. Small amounts of blood-stained mucous are passed and the dog becomes depressed, refuses to eat, but often drinks water which it vomits.
By the time these symptoms become apparent to the owner, the degree of impaction can be severe. One of the physiological functions of the large bowel is to absorb water. The longer the contents of the bowel take to pass through, the more moisture is removed until the residue resembles concrete.
The treatment of constipation of the dog is not simple. Owners often administer human laxatives, such as castor oil, which act as an irritant to the small intestine and can worsen the dog’s discomfort. Even laxatives that are designed to increase the muscle contractions of the large bowel should not be used. The bowel content is usually hard and often has protruding sharp pieces, and penetration of the wall of the bowel may result from these artificially forced contractions.
Liquid paraffin is the safest substance to administer. It is a heavy mineral oil which is not absorbed and its sole action is to lubricate the passage of the mass over the lining of the bowel.
In most cases, it is not sufficient merely to administer paraffin oil. Anesthesia of the animal is usually necessary in order to administer enemas. Solutions are used which help to break down the hardened mass into smaller fragments which can be removed carefully through the anus. It is not unusual to have to repeat the enemas two or three times over a period of 24 hours, to relieve a severe case of impaction.
Antibiotics are usually administered to prevent infection of the damaged tissues of the bowel and fluids are given intravenously to help combat dehydration and provide some source of energy to the patient, which might not have taken food for some days.
Dogs can become constipated without having eaten bones. Sometimes a long period of inactivity during bad weather or the eating of foreign substances, such as gravel or cat litter, can bring about similar problems.
As dogs age, their ability to cope with large numbers of bones diminishes. One large raw bone a week is probably enough to keep the teeth clean and free of scale.
Avoid at all costs feeding T-bone steak or chop bones, as these are usually chewed into very sharp fragments, which are swallowed. Chicken carcasses are probably the cause of most cases of severe impaction. If your pet inadvertently gets hold of these types of bones, do not wait until the dog is obviously sick. Administer liquid paraffin as soon as possible and repeat in 12 hours. Watch for any sign of vomiting or difficulty in passing a bowel motion and consult your veterinarian immediately.
Bones can become wedged in the mouth. Dogs may become suddenly distressed when eating a bone and make frantic efforts to paw at its mouth. The most common site for the lodgment of long fragments is across the hard palate between the molar teeth. The dog may be so distressed that it is necessary to anesthetize it in order to examine the mouth thoroughly.