Dog Diarrhea: Causes, When to Worry and What to Do

My Dog Has Diarrhea but Is Acting Fine

An occasional soft or loose stool in a dog that is eating, drinking and acting normally is usually not a cause for concern.² Most sudden (acute) diarrhea in dogs is mild and self-limiting: in a large study of dogs seen in general practice, 84% had mild signs, and most cases resolved within a week.⁴

If your adult dog seems well, you can usually start with simple home care: keep fresh water available, feed small amounts of a bland diet, and watch closely.^3,1 See our guide to home remedies for dog diarrhea for what to feed. If the diarrhea goes on for more than 2 days, keeps coming back, or your dog develops any of the warning signs above, call your vet.^1,3

What Causes Diarrhea in Dogs?

Common, usually short-lived causes:^3,1

• Dietary indiscretion: eating garbage, table scraps, rich or fatty food, or something found outside
• A sudden change of food or too many treats
• Stress, such as travel, boarding or a vet visit
• Intestinal parasites, such as roundworms, hookworms, whipworms, coccidia and Giardia^2,8,9

More serious causes:^3,1,2

• Viral infections such as parvovirus and distemper
• Bacterial infections and toxins, including poisonous plants
• Food allergies or intolerance
• Pancreatitis or exocrine pancreatic insufficiency (EPI)¹⁰
• Inflammatory bowel disease (IBD)
• A swallowed foreign object, cancer, or liver, kidney or adrenal disease such as Addison's disease^11,3
• Side effects of some medications²

What Your Dog's Diarrhea Can Tell You

Vets often sort diarrhea by where in the gut it seems to start, because that helps narrow down the cause:¹²

• Small-intestine diarrhea: larger amounts of stool, passed at a normal or slightly increased rate, without much straining or mucus. Any blood is digested and makes the stool look black. Weight loss may occur.
• Large-intestine (colitis) diarrhea: small amounts passed very often and urgently, often with straining, mucus and fresh red blood. Weight loss is rare. See our page on colitis in dogs.

Black, tarry stool can mean bleeding higher up in the digestive tract and needs a vet.^11,3 Red blood or mucus usually points to the large intestine. See our guide to bloody diarrhea in dogs.¹²

Watery, foul-smelling diarrhea with mucus is common with Giardia, although many infected dogs show no signs.⁹ Read more about Giardia in dogs.

Diarrhea in Puppies

Puppy diarrhea should be treated as a potential emergency.⁵ Puppies dehydrate quickly, and two common causes are serious:

• Parvovirus mainly affects young, unvaccinated dogs. Signs start with lethargy, poor appetite and vomiting, then diarrhea that is often bloody and foul-smelling. Any puppy with vomiting and diarrhea should be tested for parvo.^6,13
• Worms are common in puppies. Roundworms cause poor growth, a potbellied look and diarrhea, and hookworms can cause dark, tarry diarrhea and life-threatening anemia.⁸ See worms in dogs.

What to Do at Home for Mild Diarrhea

• Keep fresh water available at all times, because diarrhea can cause dehydration quickly.^1,3
• Feed small, frequent bland meals, such as boiled chicken or low-fat hamburger with white rice.³ Some vets suggest skipping a meal first, but feeding early is now known to help the gut recover in some conditions, so ask your vet what's best for your dog.^14,1
• Avoid treats and rich food until stools firm up, then switch back to the usual food gradually.^3,1
• Don't give human medicines such as Imodium or Pepto-Bismol unless your vet tells you to. They can be harmful to some dogs.^3,2

For recipes, pumpkin, probiotics and how long to feed a bland diet, see home remedies for dog diarrhea.

How Vets Diagnose and Treat Diarrhea

Bring a fresh stool sample if you can.^3,11 Depending on how sick your dog is, your vet may run fecal tests for parasites, bloodwork, and X-rays or ultrasound if a blockage is suspected.^3,11 Treatment depends on the cause and may include fluids, dewormers, anti-nausea medicine, a prescription diet or a probiotic.^3,1

Antibiotics aren't needed for most dogs with sudden diarrhea. Current veterinary guidelines recommend against them in mild and moderate cases, even when there is some blood, because they make little difference to recovery. Vets do use them for dogs that are severely ill or whose blood tests suggest a serious infection.⁴ See dog diarrhea treatment for more.

Preventing Diarrhea

• Change foods gradually, over a week or two.³
• Keep garbage, table scraps and toxic foods out of reach.^2,1
• Keep your dog up to date on parvovirus vaccination and parasite control. Some monthly heartworm preventives also control intestinal worms.^13,8

More on Dog Diarrhea

• Home remedies for dog diarrhea: what to feed
• Dog vomiting and diarrhea
• Bloody diarrhea in dogs
• Dog diarrhea treatment and medicines
• Blood in dog stool

Frequently Asked Questions

Why does my dog have diarrhea?

The most common causes are eating something unusual, a sudden food change, stress and intestinal parasites. Infections such as parvovirus, pancreatitis, food allergies and other illnesses can also cause diarrhea.

My dog has diarrhea but is acting fine. Should I worry?

Usually not, if your dog is eating, drinking and behaving normally. Offer water and small bland meals and watch closely. Call your vet if it lasts more than about 2 days or your dog develops vomiting, lethargy, blood in the stool or a poor appetite.

How long does diarrhea last in dogs?

Most mild cases clear up within a few days to a week. Diarrhea that lasts longer, keeps coming back or comes with other signs needs a vet check.

What is the fastest way to stop diarrhea in dogs?

There's no instant fix. Small bland meals and plenty of water help most mild cases settle within a few days. Don't give human anti-diarrhea medicines unless your vet recommends them.

Can parasites cause diarrhea in dogs?

Yes. Roundworms, hookworms, whipworms, coccidia and Giardia are common causes, especially in puppies. Your vet can test a stool sample and prescribe the right treatment.

Is diarrhea in puppies an emergency?

Treat it as a potential emergency. Puppies dehydrate quickly, and parvovirus and worms are common causes. Call your vet promptly, especially if your puppy isn't fully vaccinated, or is vomiting, lethargic or not eating.

What does parvo diarrhea look like?

Parvo usually starts with lethargy, poor appetite and vomiting, followed by severe diarrhea that is often bloody and foul-smelling. It needs urgent veterinary care.