Megacolon is an irreversible dilation of the large intestine in cats that develops from chronic, severe constipation, causing permanent inability to defecate normally and requiring either lifelong management or surgical intervention.
Megacolon causes profound suffering. Cats with impacted colons strain for extended periods, passing nothing or small amounts of painful hard stool. The accumulation of feces causes abdominal distension, nausea, loss of appetite, and lethargy. The process of manual disimpaction under anesthesia - required repeatedly in severe cases - is itself a welfare impact, adding anesthetic risk and stress to an already suffering animal. Subtotal colectomy, while major surgery, is genuinely transformative - the dramatic improvement in quality of life for post-surgical cats confirms how severely their pre-surgical existence was compromised. Prevention through early management of constipation before megacolon develops is far preferable to treating established disease.