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Constipation means absent, infrequent, or difficult defecation. Most healthy dogs have one or two stools a day. This varies with the individual and the diet. A day or even two without stools is not a cause for concern, if the stools remain normal in size and passes without difficulty. But when feces are retained in the colon for two or three days, they become dry and hard, and require forceful straining to pass.

Note that straining also occurs in dogs with colitis, obstructed bladder, and anorectic obstructions. It is important to be sure the dog is not suffering from one of these other problems before treating them for constipation. Colitis, in particular, is often confused with the constipation. Remember that a dog with colitis will pass many small stools that contain mucus and/or blood.

Causes Of Constipation

Many middle-aged and older dogs are prone to constipation. A common pre-disposing cause is failure to drink enough water. With mild dehydration, water is withdrawn from the colon which dehydrates the feces.

Ingesting foreign materials such as bone chips, hair, grass, cellulose, cloth, paper, and other substances is a well recognized cause of acute and chronic constipation. The indigestible material mixes with feces to form rocklike masses in the colon.

Many drugs commonly used in dogs cause constipation as a secondary side effect. Discuss this possible correlation with your veterinarian. Hypothyroidism is an occasional cause of chronic constipation.

The urge to defecate can also be voluntarily overridden. Dogs develop such inhibitions during housetraining. When left alone in the house for long periods, they often override the urge to defecate. Dogs may also be reluctant to empty their bowels when hospitalised, boarded, or taken on a trip.

Dogs with constipation of recent onset should be examined by the veterinarian. Other reasons to seek veterinary consultation are painful defecation, straining during defecation, and passing blood and mucus.

Treating Constipation

Eliminate or control predisposing causes. Be sure to provide access to clean, fresh water at all times. Constipation associated with ingesting foreign materials such as bone chips can be corrected by eliminating the source and giving dog biscuits to chew on instead. Older dogs with reduced bowel activity can be helped by soaking the kibble with equal parts of water and letting the mixture stand for 20 minutes.

Dogs who voluntarily retain their stool can be helped by providing frequent opportunities for the dog to eliminate. Take the dog outside several times a day, preferably to an area where is accustomed to going. A mild laxative may be needed when a dog is travelling.


A number of laxatives are available for treating constipation. Osmotic laxatives draw water into the intestines and liquefy the feces. Products containing lactulose, which must be prescribed by your veterinarian, are among the safest and most effective.

A mild osmotic laxative effect can also be obtained by adding milk to diet in amounts that exceed the capacity of the intestinal enzyme lactase to break down lactose into absorbable sugars. In other words, enough milk to cause diarrhea in a dog who is not constipated. The lactose molecule pulls into the bowel and stimulates intestinal motility.

Mild saline laxative magnesium hydroxide (milk of magnesia) acts in a manner similar to osmotic laxatives. Magnesium hydroxide is contraindicated in dogs with kidney failure.

Stimulate laxatives increase the force of intestinal peristalsis. They are highly effective in treating constipation, but repeated use can interfere with colon function. A commonly used stimulant laxative is bisacodyl (Dulcolax). The dose for dogs is 5 mg to 20 mg per day.

These laxatives are used for treating constipation only. If they are given to dog with an obstruction, they can do serious damage. They are not the laxatives of choice for preventing constipation and also not be used every day. Consult your veterinarian before you give your dog any laxative.

Preventing Constipation

Good hydration, a non-constipating diet, and regular exercise are the best preventives, along with adding fiber to the diet, if needed. A convenient way to provide the fiber is to feed a commercial food formulated for senior dogs. You can also obtain a high-fiber diet, such as Hill’s prescription w/d, from your veterinarian.

Another way to provide additional fiber is to add a bulk-forming laxative daily to the dog’s food. Bulk laxatives soften the feces and promote more frequent elimination. Commonly used bulk laxatives are unprocessed wheat bran (1 to 5 tablespoons, 15 to 75 ml per day) and Metamucil (1 to 5 tea spoons, 5 to 25 ml per day). Plain canned pumpkin (1 tablespoon to ½ cup, 100ml) depending on the size of the dog, can also help. Bulk laxatives or pumpkin can be fed indefinitely without causing problems.

Dr Sharad Singh Yadav is the Chairman of Advanced Pet Hospital & Research Centre which is open 24 hours throughout the year and located in Bishal Nagar, Kathmandu. He may be contacted on tel: 4422855 or email: aphktm@gmail.com