One of the most common medical problems we treat in dogs is Acute Diarrhea. Acute Diarrhea is characterized by the sudden onset of diarrhea in a patient. The diarrhea can range in severity from a soft stool (mushy), a stool with mucous, a watery stool, a stool with small amounts of blood to a severe explosive diarrhea with lots of bleeding.

The causes of acute diarrhea in dogs can vary. A simple change in diet, a viral or bacterial infection, parasitism like Giardia infection, intoxication, a foreign body, and other less common conditions of the bowel can be to blame.

Causes of Acute Diarrhea

New food/change in treats/ contaminated food Most common
Parasitism – Giardia Less common
Viral/bacterial infection Less common
Intoxication Rare
Foreign objects Less common
Neoplasia Rare


To determine the cause and appropriate treatment of a patient experiencing Acute Diarrhea, your veterinarian will obtain a complete history of both behavior and foods fed in the previous 72 hours. A physical exam will establish the severity of the illness. Is the patient vomiting? Is the patient experiencing abdominal pain, dehydration, lethargy or in appetence? A fecal test will determine the type of diarrhea present and check for parasitism. Significant signs of illness may warrant further diagnostics such as an x-ray and a blood test to rule out a foreign body or intoxication.

Your veterinarian will form a tentative diagnosis as to the cause of the Acute Diarrhea based on the patient history, the physical exam, and diagnostic tests. A specific treatment plan will be recommended based on the presumptive diagnosis and severity of illness.

While some pets have a more dangerous cause of their diarrhea (for example a foreign object obstructing the intestine) or severe symptoms, many patients are healthy, have only mild diarrhea and the cause is a DIETARY CHANGE. A dietary change- new treat, new chew toy, people food and contaminated food cause over 90% of cases of Acute Diarrhea. The treatment for food related Acute Diarrhea will be a cessation of a suspected offending food or chew toy, a bland diet for several days and appropriate medication to correct the diarrhea. The medication is usually Metronidazole and sometimes an antibiotic for certain bacterial infections. Probiotics can also be used.

Some pets have a propensity for recurrent episodes of Acute Diarrhea and a mild change in diet, a new treat, table food or too rich of food, may precipitate diarrhea. In these patients, we commonly recommend feeding a low fat, easily digestible intestinal diet specifically developed for dogs prone to diarrhea and feeding a single type of treat instead of a variety. We also may prescribe daily use of Tylosin to help stabilize the bacterial flora.

Finally, some patients may require more advanced testing such as specialized PCR fecal tests, abdominal ultrasound, and endoscopy to diagnose more unusual forms of diarrhea that are reoccurring or fail to respond to normal treatment protocols for Acute Diarrhea.

Treatment Of Acute Diarrhea

  • Bland diet for 72 hours
  • Anti-diarrheal medication: Metronidazole
  • Antibiotics depending upon the cause
  • Amoxicillin
  • Enrofloxacin
  • Tylosin