Skip to main content


  • Diarrhea is feces that is looser or more watery than normal.
  • Pets with diarrhea may defecate more frequently than usual, have accidents in the house, and may have blood, mucus, or parasites in their feces.
  • Puppies and kittens with diarrhea, as well as pets showing signs of vomiting and lethargy (tiredness), should be seen by a veterinarian immediately.
  • There are numerous causes for diarrhea, including eating garbage or foreign material, a sudden change in diet, viruses, and bacterial overgrowth.
  • Diagnostic tests may include fecal tests, blood work, abdominal radiographs (x-rays), abdominal ultrasound, and endoscopy with biopsy (tissue sample).
  • Treatment varies with the cause but usually includes special diets and/or medications.

What Is Diarrhea?

A pet with diarrhea has looser or more watery feces than normal and sometimes more frequent stools as well.

Many cases of diarrhea may resolve in a day or two without treatment. Pets that experience diarrhea for more than a few days, or show more severe signs, such as vomiting, loss of appetite, or lethargy (tiredness), should be seen by a veterinarian immediately. Puppies and kittens with diarrhea are especially susceptible to dehydration and require a veterinary exam.

What Are the Signs of Diarrhea?

In addition to loose or watery stools, pets with diarrhea may show signs such as:

  • Mucus or blood in the stools
  • Worms in the stools
  • Accidents in the house
  • Defecating with increased frequency
  • Straining to defecate

Other signs that may indicate a more serious problem:

  • Nausea or vomiting
  • Loss of appetite
  • Lethargy (tiredness) or weakness
  • Abdominal pain
  • Weight loss

What Causes Diarrhea?

There are many causes for diarrhea. Most commonly, it occurs when a pet eats something that is not part of his or her normal diet, such as garbage, or when the diet is changed abruptly. When changing from one kind of pet food to another, it’s best to make a slow transition over a week, gradually mixing in more of the new food and less of the old food. This transition allows the pet’s digestive system to adjust and decreases the likelihood of diarrhea.

Other potential causes of diarrhea include:

  • Bacterial overgrowth in the digestive tract
  • Viruses
  • Parasites
  • Ingestion of foreign objects, such as toys, bones, and fabric
  • Food allergies
  • Inflammatory bowel disease
  • Antibiotics and other drugs
  • Toxins
  • Pancreatitis
  • Diseases in other organs (such as liver disease)
  • Cancer

How Is Diarrhea Diagnosed?

Diagnosis may depend on the severity of the pet’s clinical signs and the length of time the pet has experienced the problem. Diagnostic tests may include:

  • Fecal tests for internal parasites, bacterial overgrowth, and viral infections, such as canine parvovirus
  • General blood tests to check for systemic diseases (diseases that affect the whole body)
  • Specific blood tests, such as thyroid panels, pancreatic tests, or feline leukemia virus tests
  • Abdominal radiographs (x-rays) to visualize possible obstructions and foreign bodies
  • Abdominal ultrasound
  • Endoscopy and biopsy (tissue sample) for chronic diarrhea cases

What Are the Treatment and Outcome for Diarrhea?

Treatment varies depending on the cause. In mild cases, your veterinarian may recommend a bland diet (a diet that will be easy for your pet’s body to digest). If there is bacterial overgrowth, your pet may need probiotics or oral antibiotics to restore the normal balance of bacteria in the digestive tract. Medications to firm the stool or treat parasites may be necessary. Diarrhea caused by ingestion of foreign objects may require surgery.

More chronic cases of diarrhea are often treated with special diets and medications. In some cases, the cause may not be completely cured and may need to be managed throughout the pet’s life.