What causes diarrhea?
Diarrhea is not a disease; rather, it is a symptom of many different conditions. Many mild cases resolve quickly with simple treatments. Common minor causes include stomach or intestinal viruses, intestinal parasites, and dietary indiscretion — eating garbage, table scraps, or other irritating material. An abrupt food change or stress can do it, too.
Less commonly, diarrhea signals something serious, such as inflammatory bowel disease, pancreatitis, organ disease, or cancer. Even diarrhea from a mild illness can become dangerous if fluid and nutrient losses go unchecked, so persistence matters as much as severity.
When is diarrhea an emergency?
Severity depends on how sick the dog has become as a consequence of the diarrhea. A dog who has one soft stool but is otherwise bright, eating, and playful can usually be watched at home for a day or two. Have your dog seen promptly if you notice any of the following:
- Vomiting alongside the diarrhea
- Dehydration (dry gums, skin slow to spring back)
- Loss of appetite
- Abdominal pain or a hunched posture
- High fever
- Lethargy
- Bloody or black, tarry stool
Puppies are a special case. Small bodies dehydrate fast, and diarrhea is a hallmark of parvovirus in unvaccinated puppies. A puppy with diarrhea should be seen the same day.
What tests are performed to find the cause?
For a dog who seems otherwise well, we start small: a fecal examination to rule out parasites and, when indicated, basic bloodwork. These mild cases are typically treated with medication to calm the intestinal tract, a bland or prescription diet for a few days, and time for the body's own healing mechanisms to work. We expect improvement within two to four days.
If your dog is systemically ill or the diarrhea persists, the workup expands: X-rays (with or without barium), broader blood testing, stool cultures, ultrasound, intestinal biopsies, or — rarely — exploratory surgery. Once the diagnosis is known, treatment may involve specific medications, a long-term diet change, or surgery.
How can I help at home?
Keep fresh water available at all times — restricting water speeds up dehydration. Withhold treats and rich foods, feed the bland diet we recommend in small, frequent meals, and pick up the yard promptly to limit reinfection from parasites. Note the stool's color, frequency, and consistency (a photo helps more than you'd think); it genuinely speeds diagnosis at your visit.
If improvement stalls after a few days of treatment, let us know — a medication change or further testing may be needed rather than more waiting.
Questions about anything here? Contact our team — we’re glad to help.