What Is The Difference Between Constipation, Obstipation, and Megacolon?

Constipation involves difficulty passing stools, often coupled with reduced frequency. Obstipation refers to complete blockage preventing defecation. Megacolon is characterized by severe dilation and inactivity of the colon, often resulting from chronic constipation or obstipation, although neurological issues can also be involved.

Animals at Risk for Megacolon

Both dogs and cats may experience constipation, but obstipation and megacolon primarily affect cats, particularly middle-aged males. Manx cats appear predisposed to neurological forms of megacolon. Risk factors include mechanical obstruction (pelvic fracture, tumor, polyps, foreign bodies, strictures, perineal hernia), neurological disorders affecting the colon, obesity, lack of exercise, insufficient hydration, or excessive stool production.

Clinical Signs

Common symptoms of megacolon include difficulty defecating, prolonged and painful straining, and the production of small, hard stools. Occasionally, liquid diarrhea may accompany constipation. Without treatment, the condition can worsen, causing loss of appetite, increased fatigue, vomiting, dehydration, and weight loss.

Mechanism of Constipation

The colon reabsorbs water from stools. When stools remain in the colon for too long, excessive water absorption hardens them, making defecation difficult and exacerbating constipation.

Diagnosing Constipation and Megacolon

Diagnosis involves a clinical examination, including rectal palpation. Abdominal radiographs confirm stool accumulation and rule out underlying issues. Blood and urine analyses may be recommended in some cases. To diagnose megacolon specifically, an abdominal lateral radiograph should show the colon’s diameter as at least twice the length of the second lumbar vertebra.

Treatment for Constipation and Megacolon

• Mild to Moderate Cases: Oral laxatives (Lactulose®, Metamucil®) and prokinetic agents (Cisapride®), alongside dietary adjustments, usually resolve the issue.
• Severe Cases: Sedation or general anesthesia may be necessary for repeated enemas. Intravenous fluid therapy often prevents dehydration.
• Advanced Megacolon: As a last resort, subtotal colectomy (partial colon removal) may be considered. This procedure involves risks and must be performed by a specialized surgeon.

Additionally, addressing any identified underlying cause is crucial to prevent recurrence.

Diet and Nutritional Management

Two dietary approaches can aid in preventing and managing constipation:

• High-Fiber Diet: Stimulates colon contractions, reduces transit time, and limits stool dehydration.
• Gastrointestinal Diet: Decreases stool production, reducing accumulation within the colon.

Early intervention and regular veterinary follow-up significantly enhance your cat’s quality of life and minimize complications associated with these digestive conditions.