Constipation is defined as infrequent or absent defecation associated with retention of feces or stool within the colon and rectum. The following circumstances lead to constipation:

1. Ingestion of indigestible material: hair, bones, wool, cloth.

2. Lack of exercise: illness or debility, obesity.

3. Painful defecation: abscessed anal sacs, tumors, draining tracts around anus.

4. Obstruction: pelvic fractures causing narrowing of the pelvis, masses obstructing colon or rectum, congenital lesions such as imperfect opening at anus.

5. Neurological disease: megacolon, paraplegia, spinal cord deformity, dysautonomia (autonomic nervous system disorder seen primarily in English cats), inflammation of spinal cord/brain.

6. Other: potassium deficiency, dehydration, certain drugs, soiled litterbox.