Causes of Dog Diarrhea and How to Control It

1 What Diarrhea Is

Diarrhea is hurried bowel movement where the large intestine fails to reclaim water, so stool comes out watery. The dog is dull, off its food, in pain, dehydrated, and may run a fever; some diarrheal diseases also vomit. The stool’s character varies with the cause — loose, watery, or bloody.

2 Reading the Stool

Mucus or pus with a sour smell and straining suggests bacterial infection. Viral causes start as pale, watery stool that turns tomato-like and foul — the hind end badly soiled.

Pale, greasy, rotten-smelling stool points to the stomach or small intestine (low acid, or short pancreatic/bile secretions).

Tar-like stool with stopped defecation suggests obstruction — intussusception, volvulus, or strangulation. Parasites bring mucus, maybe blood streaks, and sometimes worms or eggs.

3 Treatment Principles

The overall plan: anti-infection, rehydration, flora correction, and fixing the cause. For infectious diarrhea use antibiotics (e.g., penicillin, gentamicin) to clear pathogens faster — but don’t overuse them, or resistant strains and flora imbalance worsen the diarrhea.

With severe dehydration, give IV fluids to replace water, electrolytes, and energy; oral rehydration salts work for milder cases.

Diarrhea disrupts the normal gut flora, so a probiotic restores balance and fights off pathogens. Mild cases heal with diet alone: fast at first, limit water, then offer small amounts of warm, easy liquids — broth, vegetable soup, rice porridge — and build back up.