Constipation in dogs is a common digestive issue that can lead to discomfort and serious complications if left untreated. Straining to defecate, hard stools, or absence of stools are warning signs. This article explains the main causes, symptoms, and effective solutions for canine constipation.

What Are Constipation, Obstipation, and Megacolon?

• Constipation refers to difficulty passing stools, often with reduced stool frequency.
• Obstipation is a more severe form in which the animal cannot pass any stools.
• Megacolon is an excessive dilation of the colon, resulting in a loss of intestinal motility. It usually follows severe constipation or prolonged obstipation and may, more rarely, have a neurological origin.

Causes of Constipation and Obstipation in Pets

While both dogs and cats can suffer from constipation, obstipation and megacolon are more commonly seen in cats, especially middle-aged males. A neurological predisposition to megacolon has also been reported in Manx cats.

Various factors increase the risk of constipation or obstipation:

• Mechanical obstruction (pelvic fractures, tumors, polyps, foreign bodies, strictures, perineal hernias)
• Neurological disorders (traumatic injury or degenerative disease of the caudal spinal cord)
• Environmental factors (sedentary lifestyle, obesity, low water intake, poor diet)

Symptoms of Constipation in Dogs and Cats

Pet owners may notice:

• Prolonged, painful, or unsuccessful defecation
• Small, round, very hard stools
• Occasionally, watery diarrhea alongside hard stools
• In chronic cases: loss of appetite, lethargy, vomiting, dehydration, abdominal pain, and weight loss

How Is Constipation Treated in Dogs and Cats?

The colon plays a key role in reabsorbing water from stool. If stools remain in the colon too long, they become too dry and difficult to pass.

Diagnosis:

• Physical examination, including rectal palpation
• Abdominal radiographs to rule out underlying causes and confirm megacolon
• Blood and urine tests when necessary

Megacolon is diagnosed when a lateral abdominal X-ray shows the colon diameter exceeding twice the length of the second lumbar vertebra.

Treatment:

Mild to moderate cases:

• Combination of laxatives (e.g., Lactulose®, Metamucil®), prokinetic agents (e.g., Cisapride®), and a high-fiber diet

Severe cases:

• Enemas under sedation or general anesthesia, possibly repeated
• Intravenous fluid therapy is often needed

Extreme cases (end-stage megacolon):

• Subtotal colectomy (removal of part of the colon) may be considered as a last resort. This delicate surgery, prone to complications, should be performed by a specialist.

Note: If an underlying cause is identified, it must be addressed to prevent recurrence.

Prevention: How to Avoid Constipation in Your Pet

• Choose a high-fiber diet
• Encourage adequate hydration
• Promote regular physical activity