Table 58-8.

Causes of Constipation

Type	Cause
Mechanical obstruction
Intraluminal	Bones, hair, neoplasia, rectal diverticulum, stricture, deviation/sacculation associated with perineal hernia
Intramural	Neoplasia
Extramural	Pelvic fractures, neoplasia, prostatic disease
Inflammation	Perianal fistula, anal sac disease, perineal wounds
Neuromuscular dysfunction	Lumbosacral disease, cauda equina syndrome, sacral spinal cord deformities (Manx cat) Hypogastric or pelvic nerve disorders–trauma, neoplasia, dysautonomia Colonic smooth muscle–idiopathic megacolon
Metabolic, endocrine	Dehydration, hypokalemia, hypocalcemia Hypothyroidism, nutritional secondary hyperparathyroidism, obesity
Pharmacologic	Opioids, atropine, anticholinergics, diuretics, barium sulfate, phenothiazines, β-agonist drugs
Environmental	Soiled/absent litterbox, inactivity, hospitalization, multicat households, competition

Adapted from Washabau RJ, Hasler AH: Constipation, obstipation, and megacolon. In: August JR, editor: Consultations in Feline Internal Medicine, ed 3. Philadelphia, 1997, Saunders, p 106.