Dog: Diarrhea

General information

Diarrhea is the increase in frequency, fluidity or volume of feces or stool. Diarrhea is described as being either acute (less than 3 weeks duration) or chronic (greater than 3 weeks duration). Acute diarrhea is common in dogs due to their indiscriminate eating habits. Diarrhea can be caused by diseases of the small intestine, large intestine or secondary to an underlying condition.

If your dog is bright and alert and only has one bout of diarrhea, it may not be necessary to call your veterinarian. However, it is important to call your veterinarian when:

  • Your dog has continued diarrhea for more than 24 hours.
  • Your dog appears bloated.
  • You suspect your dog may have eaten something toxic or poisonous.
  • Your dog has a fever or is depressed.
  • Your dog is in pain.
  • Your dog is a puppy and has not been dewormed.


Intestinal Causes

Secondary Causes


Intestinal infections which cause vomiting can be spread from dog to dog through fecal material, respiratory secretions and urine.

Cardinal symptom



Depending on the cause, acute diarrhea can present with other clinical signs including lethargy, abdominal pain, vomiting, fever and lack of appetite.

Clinical signs of chronic diarrhea can be described as originating from the small intestine or the large intestine. Dogs with chronic diarrhea from the small intestine may have a slight increase in the frequency of bowel movements but tend to have larger amounts of stool. These dogs may also vomit and lose weight. If there is blood in the stool, it is dark and tarry. Dogs with chronic diarrhea from the large intestine will pass smaller amounts of stool but more frequently, usually more than 5 times daily. These dogs are in good flesh with no weight loss. They will strain to pass stool which may be slimy with mucous. Bright red blood is commonly seen with large bowel diarrhea.


The diagnosis of diarrhea is straight forward. However, finding the cause can be more difficult. It is helpful to know when the diarrhea started, the appearance of the diarrhea and if your dog is acting sick. A complete physical examination plus the following diagnostic tests may be used:

  • Fecal examination: used to detect parasite eggs and Giardia spp.
  • Complete blood count (CBC): used to measure the white blood cells and red blood cells.
  • Serum biochemistry: used to assess internal organ function including liver, kidneys, pancreas and intestinal tract.
  • Electrolyte panel: measures electrolytes, acid-base status and blood pH.
  • Urinalysis: used to detect abnormalities in the urine.
  • Radiography: abdominal radiographs can help identify foreign bodies, neoplasia and assess organ size and structure.
  • Ultrasonography: ultrasonography can obtain a three dimensional image of the internal organs.
  • Endoscopy: uses a flexible tube with a lighted scope which is passed through the esophagus and into the stomach to visualize the lining and lumen of the stomach. Endoscopy can also be used to obtain tissue samples for cell identification.
  • Exploratory laparotomy: abdominal surgery performed under general anesthesia in order to visualize and inspect the abdomen and internal organs. Tissue samples can be obtained from organs and/or the lining of the intestinal tract for cell identification.


Treatment of diarrhea will depend on the cause. Mild cases of diarrhea without an underlying disease are treated by withholding food for 24 hours. Afterwards, a bland diet of rice, boiled chicken and cottage cheese can be fed in several small meals to allow the intestinal tract to heal. Antidiarrheals can be administered to help with diarrhea. Dogs with intestinal parasites should be dewormed. With severe cases of diarrhea, hospitalization and intravenous fluid and electrolyte therapy are indicated. Intestinal obstructions and foreign body ingestion usually require abdominal surgery to remove the foreign object or correct the obstruction. Other treatments and medications may be needed depending on the exact cause of diarrhea.


Most cases of diarrhea in dogs are mild and resolve completely with minimal treatment. However, chronic diarrhea may be an indication of a serious disease requiring intensive treatment or possibly surgery.


Diarrhea due to parasites can be prevented by regularly deworming your dog. Many of the monthly medications used to prevent fleas, ticks and heartworm disease also treat intestinal endoparasites. Veterinarians recommend that most dogs be given these monthly medications year round. All dogs should have an annual fecal examination performed.


Prolonged diarrhea especially when accompanied with vomiting can cause life-threatening dehydration and electrolyte imbalance especially in puppies and older dogs requiring immediate veterinary care.

Update version: 4/24/2014, © Copyright by
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