Constipation in dogs can be treated with a stool softener or other laxative, an enema, or with medication that increases the contractile strength of the large intestine. Increasing a dog's exercise or switching to a diet high in fiber can also help to cure constipation.
The various causes of constipation in dogs fall into one of three categories: interluminal, extraluminal and intrinsic. Interluminal constipation is caused by obstruction of the inside of the colon, which occurs when something cannot be properly digested or when a tumor is present. Extraluminal constipation is when the outside of the colon becomes compressed. Intrinsic causes refer to neuromuscular injury or disease.
Signs of constipation include a dog straining or crying when trying to defecate, or a dog not having a bowel movement in two or more days. Sometimes a dog might also appear to be bloated. If the dog is able to release a stool, it may contain blood or mucus or be darker than normal, all of which are signs of internal distress.
Constipation that is left untreated can cause a backup of feces in the dog's colon, leading to lethargy, appetite loss and vomiting. A veterinarian can best evaluate which treatment is best for the affected dog.