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What causes Diarrhea in Dogs?

Dr. Kurt Venator, DVM, PhD, Chief Veterinary Officer, Nestle Purina Pet Care

Diarrhea is a relatively common problem in dogs.  Primary causes of sudden onset dog diarrhea include dietary indiscretion – also known as “garbage gut”, sudden change in diet, stress, or viral, bacterial, or parasitic infection.  Often acute diarrhea in dogs can be self-limiting and appropriately managed by consulting your veterinarian.

Tan, large breed dog sniffing close to the grass has diarrhea and searching for a place to relieve himself.

Dog diarrhea is defined as liquid, watery or runny, frequent bowel movements, affecting either the small or large intestine. While most cases of diarrhea will pass within 12 to 24 hours, dogs that display symptoms beyond 24 hours should be evaluated by a veterinarian.


How do dogs get diarrhea?

Acute diarrhea is a relatively common occurrence in dogs and is often self-limiting.  In contrast, chronic diarrhea is often associated with a more serious underlying medical condition.


Acute Diarrhea causes:


Chronic Diarrhea Causes:


While some types of dog diarrhea will resolve naturally in 24 hours, dogs that continue to excrete water-like feces, or feces with traces of blood, for longer than 24 hours, should be evaluated by a veterinarian.  The dog intestine is a sensitive organ that can be easily damaged if a dog ingests something that cannot be digested, for example, sticks, bones, toys.


A number of tests to establish the cause may be recommended, including:  physical exam, urinalysis, blood tests, stool examination, x-rays, an ultrasound, or endoscopy.


What signs will a dog have?

As a pet parent, you’ll likely deal with dog diarrhea at some point; most of the time, there’ll be nothing to worry about as it will resolve on its own. However, knowing what to look for, when to get treatment and how to prevent diarrhea will help you better manage your dog’s health, and ensure he recovers in the least amount of time.


Whether the symptoms of diarrhea are mild or severe, you should always contact your nearest veterinarian for advice within 24 hours if any of these signs persist. Some signs of diarrhea may include:


  1. Liquid stools that look like puddles of mud
  2. Watery stools that are red or black in color, or contain blood
  3. Unformed stools that are slimy or contain mucus
  4. Dried blood or mucus around the dog’s anus
  5. Large amounts of stool being passed with more frequency (5+ times per day)
  6. Loose stools passed in small amounts with more frequency (5+ times per day)


Contact a veterinarian immediately if your dog has diarrhea and is:

  1. A puppy under 6 months, a dog considered senior, or a dog under 10 lbs.
  2. Diagnosed with a pre-existing condition such as diabetes, kidney disease etc.
  3. Struggling to breathe, or has labored breathing
  4. Passing runny stools more than 5 times a day
  5. Vomiting, or retching consistently (3 or more times in 24 hours)
  6. Passing small amounts of blood
  7. Expelling slimy with mucus, or greasy-looking feces
  8. Sudden weight-loss and lethargy
  9. Dehydrated, with a dry, dull, brittle coat
  10. Showing signs of depression, pain


Home remedy vs Veterinarian treatment

If a dog has diarrhea without any of the listed symptoms in this article, you may be able to monitor his progress and recovery at home over 24 hours.  Often, diarrhea is caused by stress, or by the dog ingesting something from the trash that isn’t part of his daily diet.


Home remedy management of acute diarrhea (sudden diarrhea that is likely to pass in 24 hours) could include the following:


  • Withhold food for 24 hours.
  • Provide lots of fresh, clean water.
  • If diarrhea stops, feed regular sized serving broken up into 3 to 6 small, bland meals.
  • Bland meals could be made up of boiled, white rice and chicken without bones or skin.
  • If dog digests first small meal with no side effects, offer a second 3 to 4 hours later.
  • Feed a slightly bigger third meal again in 3 hours if dog seems fine.
  • Serve a fourth, larger meal 2 hours later if dog is doing well.
  • Increase meal size again, and feed an hour after fourth meal.
  • Final meal should be feeding the remainder of the bland food.
  • Continue regular feeding schedule the next day.


Veterinary treatment is highly recommended for any dog experiencing diarrhea for longer than the 24 hour observation period or showing the clinical signs listed above.  At your visit, be prepared to answer some very important questions from the veterinarian that could help determine the cause of the dog diarrhea, such as:


  • Has your dog experienced any big changes that could cause stress?
  • How often during the day is the dog needing to go outside to relieve himself?
  • Has the dog eaten anything other than his regular meal or dog food?
  • When was your dog’s last meal?
  • Did you bring a stool sample to the veterinary practice?
  • Has the dog had diarrhea for more than 24 hours?
  • Does the dog have any pre-existing conditions?
  • What are the current medications for these conditions, if any?


Do not give your dog human medicine, which can be highly dangerous, unless it is specifically prescribed by your veterinarian.


How to prevent dog diarrhea

The simplest way to keep your dog healthy is to be aware that:


  • Objects, such as toys, bones or even small items of clothing lying around can be ingested.
  • Switching a dog’s diet can cause severe stomach upsets.
  • Food transitions should be completed over 7 to 10 days to avoid an upset stomach and diarrhea.
  • Scavenging for food in the trash or elsewhere, and human foods should be discouraged.
  • Meaty treats with bones can cause potentially dangerous obstructions.
  • Regular vaccinations and veterinarian check-ups keep dogs healthy.
  • Food for a sensitive stomach may help your dog avoid diarrhea.

Still have questions about caring for your dog? Find dog health answers.


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