Diarrhea in Dogs

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Diarrhea in dogs—commonly defined as loose, runny stool, although any stool that is not firm and fully formed can be referred to as diarrhea—has a wide range of possible causes. Some of the diseases or conditions that produce diarrhea are mild, while others are more serious.

Just like humans, dogs will occasionally have diarrhea. A single episode is typically not something to worry about, as long as your dog is otherwise feeling well. However, if your dog has several episodes of diarrhea in a short period of time or has chronic diarrhea, it is time to call your veterinarian. Frequent diarrhea causes dehydration. This is dangerous for all dogs, but especially for young, old, or immunocompromised dogs.

Knowing what to do when your dog develops diarrhea can make a big difference in their recovery.

Signs and Symptoms of Diarrhea in Dogs

A single case of diarrhea is not usually a cause for concern, but if your dog has several bouts of diarrhea in a short period of time (1 to 2 days), or has chronic diarrhea, contact your veterinarian. Be prepared to describe the diarrhea as well as any accompanying symptoms.

Knowing how to describe your dog’s condition properly will help you and your veterinarian find a solution as quickly as possible. While it may seem unpleasant to examine your dog’s feces, stool provides valuable clues about your dog’s health. Here are some symptoms and descriptions you may want to refer to when speaking with your vet:

  • Loose, liquid stool
  • Watery stool
  • Bloody diarrhea
  • Frequent bouts of diarrhea
  • Appetite loss
  • Abdominal discomfort
  • Bile in diarrhea
  • Mucus in diarrhea

Bloody diarrhea, whether the blood is bright red or black and tarry, is always cause for concern. Red blood in the stool, or hematochezia, is usually due to bleeding or irritation lower down in the intestinal tract. Black, tarry stool, or melena, is due to bleeding in the stomach or upper small intestines. If you see blood of any kind in your dog’s stool, call your vet immediately.

Why Does My Dog Have Diarrhea?

There are many potential causes of diarrhea in dogs. Here are some of the categories:

  • Viral
  • Bacterial
  • Intestinal disorders
  • Cancer
  • Immune disorders
  • Toxicity
  • Diet
  • Environment
  • Parasites
  • Stress

Diarrhea is a symptom of many viruses and bacteria. In puppies, perhaps the most dangerous viral agent is the parvovirus, which is known for producing copious amounts of diarrhea. Distemper, herpesvirus, coronavirus, rotavirus, and other viruses can also cause diarrhea. Bacteria, like Clostridium, salmonella, and campylobacter, often lead to diarrhea as well.

Intestinal disorders commonly share diarrhea as a symptom. Malabsorption, colitis, hemorrhagic gastroenteritis, and inflammatory bowel disease can all cause diarrhea. Some forms of cancer may lead to conditions that create diarrhea, as can some autoimmune disorders.

Diet can certainly be a cause of stomach issues, especially if you have suddenly switched your dog to a new diet. This is why gradually introducing new dog food by mixing it with the old is important. Consumption of toxic substances, such as garbage, salt water, or certain human foods, causes diarrhea in many cases. Occasionally, environmental factors like stress can also cause watery stools.

Many intestinal parasites cause diarrhea. Protozoa cause diseases like giardiasis, coccidiosis, and amebiasis, while intestinal parasites like roundworms, hookworms, whipworms, and tapeworms also cause diarrhea.

Diagnosing Diarrhea in Dogs

Of course, it’s not hard to tell when your dog has diarrhea—but diagnosing its cause requires you to give your veterinarian some information. Vets diagnose diarrhea in dogs based on medical history, the owner’s description of symptoms, a physical exam, blood work, and diagnostic tests like fecal exams (for parasites), radiographs, ultrasounds, and anything else they deem necessary based on your particular dog’s situation.

Getting detailed information from the owner is especially important for cases where a toxin or foreign substance may have been consumed. Knowing that a dog had access to a potentially dangerous substance can save time—and the dog’s life.

In other, less acute cases, it may take time to determine the underlying cause of the diarrhea. Your veterinarian may require follow-up visits and repeat diagnostics, if they suspect the cause is serious.

Treating Diarrhea in Dogs

The treatment for diarrhea in dogs will depend on the cause. In some cases, hospitalization may be required. Other cases may call for antiparasitic medications or antibiotics. Medications designed specifically to treat diarrhea in dogs do exist. Activated charcoal helps absorb some of the toxins that cause diarrhea, while motility-modifying medications like anticholinergic drugs and opiates slow down your dog’s motility, reducing the urgency of the diarrhea and helping to reduce dehydration. (However, the use of activated charcoal or narcotics to control diarrhea in dogs is quite uncommon.)

In other cases, your vet may need to treat your dog for underlying bacterial, viral, or parasitic infections. Sometimes it may simply be a matter of adjusting your dog’s diet.

The most important thing you can do to stop your dog’s diarrhea is contact your veterinarian. Many of the potential causes of diarrhea in dogs are serious and require veterinary care and prescription medications to treat.

Is There a Cure for Diarrhea in Dogs?

In most cases, diarrhea is a problem that can be resolved by your veterinarian. However, there’s no permanent “cure” that will prevent your dog from ever having diarrhea again.

Is Diarrhea Contagious for Humans or Other Pets?

Some causes of diarrhea in dogs may be contagious to other dogs; if you have other dogs in the household, ask your veterinarian about the possibility of contagion.

There are a few causes of diarrhea that are theoretically zoonotic, such as giardia; however, it’s extremely unlikely that other pets or people in the household will contract the cause of your dog’s diarrhea. But of course, it’s always smart to maintain good hygiene around any animal that is sick.

What Is the Cost for Treating Diarrhea in Dogs?

The cost of treatment for diarrhea in dogs will include a vet visit, but can vary after that depending on how many tests are needed to diagnose the cause. (If your vet can pinpoint a reason simply by talking to you, a diagnosis may require fewer tests.) You may incur additional fees if medications and follow-up visits are necessary.

In the most serious cases, hospitalization and supportive care will be necessary. These will add significantly to the costs.

Recovery and Management of Diarrhea in Dogs

The time it takes for your dog to recover from his diarrhea will vary. If the cause is serious, hospitalization and supportive care may be necessary. In mild cases, the diarrhea might clear up in as little as several hours. Your veterinarian will provide you with medication if they feel it is required.

Once you’re back home, be ready to take your dog out to relieve himself at a moment’s notice. Make arrangements for your dog to be monitored and taken out frequently if you will not be home, and consider crating your dog without bedding for easier clean up.

Bear in mind that some causes of chronic diarrhea, like diarrhea caused by a food allergy or intolerance, will take patience on your part as you take measures like elimination diets to determine the irritant.

Preventing Diarrhea in Dogs

Some cases of diarrhea are preventable. Vaccinations exist for viral conditions like distemper and parvovirus. Preventing your dog from consuming toxic substances or substances like garbage, salt water, and human food can reduce their risk of diarrhea from toxicity and indigestion. Keeping your dog up to date on parasite prevention will help reduce the risks of parasites, too.

Other causes of diarrhea, like cancer, immune conditions, or bacterial infections may not be preventable. In these cases, early intervention from your veterinarian is the best way to prevent major complications.


While a single episode of diarrhea in dogs is usually not cause for concern, repeated episodes should always be investigated by a veterinarian, to diagnose and treat the underlying cause, and ensure your dog doesn’t suffer from dehydration. If caught early (and depending on the root cause), diarrhea is usually treatable and dogs will recover well.

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