Diarrhea in Dogs

By Ryan Llera, BSc, DVM; Krista Williams, BSc, DVM; Ernest Ward, DVM

Dog owner getting bag out to pick up dog pooWhat is diarrhea?

Diarrhea is unformed or loose stools, usually occurring in larger amounts and/or more often than usual. Diarrhea is not a disease but rather a clinical sign of many different diseases. Diarrhea associated with minor conditions can often be resolved quickly with simple treatments. Diarrhea may also be the result of serious or life-threatening illnesses such as organ system failure or cancer. Even diarrhea caused by mild illnesses may become serious if treatment is not begun early enough.

What causes diarrhea?

Diarrhea is the result of faster movement of fecal material through the intestine, combined with decreased absorption of water, nutrients, and electrolytes. If the main sign of illness in your dog is diarrhea, a relatively simple problem such as an intestinal infection from bacteria, coccidia, or intestinal worms (hookworms, roundworms, whipworms) may be the cause. In dogs, dietary indiscretion (eating garbage or other offensive or irritating materials) or a change in diet are common causes of acute (sudden) diarrhea. Stress, especially following travel, boarding, or other changes in the environment, can also cause acute diarrhea

Diarrhea can also be a sign of a more serious underlying disorder such as allergies, bacterial or viral infections (such as parvovirus), inflammatory bowel disease, organ dysfunction, or other systemic illnesses.

How serious is diarrhea in dogs?

The seriousness of diarrhea depends on how long it persists and how many other clinical signs accompany it. If your dog has severe bloody diarrhea or is showing more generalized signs of illness such as weakness, fever, vomiting, abdominal pain, loss of appetite, or dehydration, the cause may be more serious and medical attention should be sought as soon as possible. For example, diarrhea is one of the first signs seen in parvovirus, a viral infection that can cause life-threatening illness in susceptible dogs.

"...diarrhea is one of the first signs seen in parvovirus, a viral infection that can cause life-threatening illness in susceptible dogs."

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How is the cause of diarrhea determined?

The nature of the diarrhea, such as its color, consistency, smell, and frequency, is important in determining the cause. Your veterinarian will usually request a sample of fresh fecal material be brought to your appointment. You may also be asked to provide answers to a series of questions. To help you prepare this information for your veterinarian, see the handout "Diarrhea Questionnaire for Dogs".

In mild cases of diarrhea, further diagnostic testing may be deferred unless initial treatment fails, or the condition worsens. Additional tests may include blood work, stool and rectal swab samples for parasite examination, DNA testing, bacterial culture, radiographs (X-rays), ultrasound, and endoscopic exam.

What is the treatment for diarrhea?

For otherwise healthy adult dogs, your veterinarian may advise you to withhold food for up to 24 hours or to feed small quantities of a veterinary diet for gastrointestinal problems. These diets are specifically formulated with a balance of fibers that feed the good bacteria found in your dog’s intestine and with certain antioxidants that support your dog’s immune system while recovering.

"Anti-diarrheal agents, de-wormers, and/or probiotics may be prescribed."

Anti-diarrheal agents, de-wormers, and/or probiotics (bacteria that support intestinal health) may be prescribed. There are several probiotic products that may be helpful in dogs with diarrhea. As the quality and effectiveness of these products are not always known, consult your veterinarian before offering anything to your dog. Many cases of acute diarrhea respond quite readily to this conservative treatment, allowing the body's healing mechanisms to correct the problem, without the initial cause ever being established. As the stools return to normal, your dog’s regular diet can usually be transitioned from the prescribed veterinary diet over seven to ten days.

If your dog is not improving within two to four days, further tests or more aggressive treatment may be necessary. Severe or prolonged diarrhea can result in significant dehydration and metabolic disturbances due to fluid loss and your dog may require hospitalization for intravenous fluid therapy or other, more intensive, treatments.

What is the prognosis?

The prognosis depends upon the severity of the diarrhea, the specific diagnosis, and your dog's response to treatment. Most cases of simple diarrhea will make a full recovery, while dogs with chronic diarrhea may require dietary management or medication to keep the condition under control.

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