Diarrhea In Dogs: Causes & Treatment

Beagle puppy eating

Diarrhea is common in dogs.

Whether your dog is a young puppy, that has not has completed all their vaccinations, or your dog is old, talk to your vet if your dog has diarrhea.

Both very young and old dogs are susceptible to dehydration. Parvovirus can cause life threatening diarrhea in puppies that not have completed their vaccinations.

Diarrhea can either be acute (comes on suddenly and is over in a short period of time) or chronic (comes on gradually (usually) and persists or is recurrent).

Find out;


Causes of Dog Diarrhea

Diarrhea can have many causes, such as;


Some of these categories can overlap. The most common are “dietary indiscretion” and parasites.

Dietary Indiscretion

Eating inappropriate stuff comes with the territory with dogs. Dogs are natural scavengers and will eat all kinds of things. Examples of “bad” choices include trash, dead animals, rotting food, plants, wood, plastic, rubber and pretty much anything you can think of.

Anything that is irritating to the digestive tract of a dog can cause vomiting and/or diarrhea.

If the diarrhea persists, it could be poisoning or there could be a chronic infection developing. Take your dog to a vet.


Dogs can pick up parasites from various sources depending on the particular intestinal parasite. If a dog has chronic diarrhea, parasites may be the cause. When you visit the vet take a stool sample. Once the type of parasite has been identified then the parasites can be killed and eliminated with the appropriate medication.

Some preventative medications such those for heartworm are also effective against some of the intestinal parasites; see Table of common heartworm preventative medications.

Intolerance to One or More Foods

This is not the same as food allergy. When a dog has a food allergy, the body reacts by triggering a hypersensitivity response that involves a particular type of antibody known as IgE. The most common symptom of a food allergy is itchy skin (see Allergies) not diarrhea.

With food intolerance, the result is usually a rapid transit of the food through the intestine and hence diarrhea. There are a wide range of foods that can cause food intolerance. You can try changing the food or eliminate different foods from the diet. There are a range of specially formulated dog foods available, both commercially and at the vet, that can be tried in the case of suspected food intolerance.

If your dog eats foods that contain milk or milk-byproducts, this is one of the first things to try eliminating. Like humans dogs can be lactose intolerant.

Sudden change in diet

Some dogs are very sensitive to changes in diet. A change from one type of dog food to another can upset their digestive tract.

To stop this happening it is recommended not to make a sudden switch but to have a transition period where slowly the amount of the old food is reduced and the new food increased at feedings.

Sudden stress

Stress can give some dogs diarrhea. A trip to the vet or other stress, such as a new owner, can cause a dog to have diarrhea. Once the dog is no longer in the stressful situation or relaxes, the diarrhea will stop.


Though overeating is more likely to cause vomiting, it can occasionally cause diarrhea.


A number of substances, that are poisonous to dogs, can cause diarrhea as part of their symptoms. If you know, or suspect, that your dog has consumed a poison, seek veterinary care immediately. You can check out the Animal Poison Control Center if you are not sure if the substance consumed is a poison – however if your dog is really sick assume they have consumed a poison and get vet help immediately.

Bowel diseases

There are a number of bowel diseases that will cause chronic diarrhea. These include inflammatory diseases and malabsorption syndrome. If bowel disease is diagnosed, your vet may prescribe medications and will often recommend dietary changes.

Chronic infection

Most infections that involve the digestive tract will cause acute (short-lived) diarrhea, but some can also cause chronic diarrhea. Antibiotics may be prescribed by your vet if a persistent infection is suspected.

Side effect of some medications

Some medications may cause diarrhea in some dogs. Read the information provided with medications, so that you are aware of any potential side effects.

Treatment of Diarrhea

As stated above, if your dog is young, old or has any underlying health problems seek veterinary advice.

Very young and very old dogs do not cope well with dehydration. The loss of fluid that accompanies diarrhea can cause problems, or even kill very young and old dogs.

If your puppy has not had all its vaccinations, take your dog to your vet immediately. Parvovirus is a life threatening infection.

Symptoms that require veterinary attention

If the diarrhea in any age of dog

  • contains blood
  • has a black and a tarry consistency
  • episodes of vomiting
  • fever
  • weak or listless
  • gums are pale or have a yellowish look
  • rapid pulse


Also, if the diarrhea persists and is not tailing off by 24 hours or gone by 48 hours, get veterinary guidance.

Treating Acute Diarrhea

In a dog that is otherwise healthy and not a young puppy or very old dog, acute diarrhea can often be treated at home.

Since diarrhea is due to irritation of the digestive tract it is important to rest the tract by not giving any food to the dog for about 24 hours. To reduce the risk of dehydration the dog should be encouraged to drink water. Drinking water does not cause irritation.

Some vets will suggest that if the diarrhea has lasted more than a day, that you can try a half and half mixture of water and Pedialyte, in place of water, if the dog will drink it.

Another treatment for diarrhea is to give your dog Pepto-Bismol.

Pepto-Bismol or Kaopectate are usually recommended at 0.5 -1ml per lb (1 fl oz per 15 to 30 lbs) every 6 to 8 hours. Regular strength Pepto-Bismol – ¼ tablet per 20 lbs every 6 to 8 hours. Liquid is preferred over tablets, if possible. The best way to give the liquid is using a syringe (without a needle!) and squirting the Pepto Bismol into the cheek pouch (inside the cheek, outside the teeth towards the back). It can be a bit messy, so do it somewhere that is easy to clean, such as in the kitchen.

Pepto-Bismol will darken the stool, and may cause constipation in some dogs.

Using probiotics

To help restore the balance of bacteria in the gut during and after diarrhea, probiotics may be helpful. For more information on probiotics see Probiotics; What Are They? Are they Effective For Dogs?.