Cat constipation can be a real headache. If it is not treated, it could develop internal infections which are much harder to treat.

There are home remedies that we can try before visiting a vet:

Some cats enjoy beans, pumpkin, or even fruits and veggies. If your cat enjoys such, offer cooked vegetables along with soft food to help your constipated cat. - What Should I do for My Constipated Cat?

The cause of constipation could vary in cases. Most of them are due to dehydration which can easily be fixed by introducing more fluid in their diet. Others could be stress or blockages.

The constipated cat may have a slightly narrowed colon, which can cause difficult passage of feces. This condition cannot be treated successfully in most cases, but one can compensate by giving the cat softer or canned food, and by supplementing the cat’s diet with dietary fiber, as per a vet’s directions.

In some cases, cats may suffer from obstipation, defined as total absence of bowel movements. This condition is extremely serious as it may indicate a fatal bowel obstruction. A cat that has had no bowel movements for several days, is vomiting, and seems weak should be seen by a vet immediately for treatment. - What Should I do for My Constipated Cat?

Follow the link below to read the full article regarding cat constipation:

http://www.wisegeek.com/what-should-i-do-for-my-constipated-cat.htm