What causes diarrhea?

Diarrhea is not a disease; rather, it is a symptom of many different diseases. Many mild cases of diarrhea can be resolved quickly with simple treatments. Others are the result of fatal illnesses, such as cancer. Even diarrhea caused by mild illnesses may become fatal if treatment is not begun early enough to prevent severe fluid and nutrient losses.

How serious is diarrhea in dogs?

We attempt to determine how sick the dog has become as a consequence of the diarrhea. When the dog is systemically ill (i.e., more than one body system is involved), some of the following may be noted:

  • Vomiting
  • Dehydration
  • Loss of appetite
  • Abdominal pain
  • High fever
  • Lethargy
  • Bloody and/or watery diarrhea

What types of tests are performed to find the cause?

If diarrhea is associated with several of the above signs, we perform a series of tests in the hope that a diagnosis can be made. This permits more specific treatment. Diagnostic tests may include radiography (x-rays) with or without barium, blood tests, stool cultures, biopsies of the intestinal tract, and exploratory abdominal surgery. Once the diagnosis is known, treatment may include special medications and/or diets, or surgery.

If your dog does not appear systemically ill from diarrhea, the cause may be less serious. Some of the minor causes of diarrhea include stomach or intestinal viruses, intestinal parasites, and dietary indiscretions (such as eating garbage or other offensive or irritating materials). A minimum number of tests are performed to rule out certain parasites and infections. These cases may be treated with drugs to control the motility of the intestinal tract, drugs that relieve inflammation in the intestinal tract, and, often, a special diet for a few days. This approach allows the body’s healing mechanisms to correct the problem. We expect improvement within 2-4 days; if this does not occur, a change in medication or further tests are done to better understand the problem. Please keep us informed of lack of expected improvement so that we may manage the situation properly.