Occasional cat constipation which resolves itself in a day or two is not a cause for alarm. If the constipation happens frequently or does not resolve itself, that should cause alarm and a call to action because your cat has a problem.
Causes of Cat Constipation
The most common cause of cat constipation is a dietary issue, usual the cat is not getting enough fiber in her diet. Some cats do not have access to enough water and that too can cause hard, difficult to pass stools. Long-haired cats are also predisposed to constipation because of all the hair they swallow when grooming.
If a cat’s litter box is dirty or moved to a different location the cat may refuse to use it and become constipated. Certain types of feline medications can cause constipation. A pelvis which has been recently fractured or fractured in the past may leave behind nerve damage that impedes healthy, normal defection for the cat. Any obstruction within the colon will involuntarily block the passage of feces and cats may voluntarily hold in their feces if they have an infected anal sac or other rear-end issue that makes defecating painful.
Cures for Cat Constipation
Since the most common cause of cat constipation is a dietary issue, often a change in the diet resolves the issue. Switching your cat to a diet high in fiber helps keep things moving along normally. Sometimes the simple addition of a high fiber food, like a spoonful of canned pumpkin or crushed psyllium, to the cat’s existing food intake is all that’s needed. A high fiber diet helps keep loose hair moving along so it does not become an impaction in the colon or a hairball on the floor. Some veterinarians take a different approach to treating cat constipation and recommend only feeding a low fiber diet which consists of wet, canned food to the cat to resolve current bowel issues and prevent future constipation.
When diet change alone is not enough, your veterinarian may prescribe a laxative or stool softeners for the cat. For extreme cases involving impaction, a cat may require hospitalization so the veterinarian can administer enemas, and if that does not relieve the problem, surgical manipulation of the colon may become necessary.
Source: http://pets.webmd.com/cats/cat-constipation-and-fecal-impaction