Skip to main content

Why does my dog have diarrhea? (and when it’s time to see the vet)

Your dog has the runs — should you run to the vet?

Valeriia Miller / Pexels

Being a dog parent can be a joyful experience — no matter what your boss thinks of you, you can count on your pup to show you affection when you walk in the door. In exchange for their unconditional love and affection, dogs require that we take care of them and — sigh — pick up their poop (your neighborhood’s code enforcement requires the latter, to be more precise). Cleaning up after a dog also gives pet parents a role they may not have expected when they brought their furry friend home: Poop inspector.

Poop is a sign of a dog’s overall health. Regular, firm stool that resembles a caterpillar is one sign your pup is feeling well. If the stool is loose, you may need an answer to the question, “Why does my dog have diarrhea?” That depends. While we can’t answer the question definitively, we can provide some common causes of diarrhea and what to do.

sick brown puppy sitting by hose
Brixiv / Pexels

Why does my dog have diarrhea?

We can’t tell you for sure. However, diarrhea occurs when a dog’s fecal movement moves through the intestines more quickly, and their body absorbs less water, electrolytes, and other nutrients. The result? Loose stools. Sometimes, a dog’s diarrhea can be completely liquid.

Gross? Yes, but it is true — dealing with doggie diarrhea is part of the nature of dealing with the (lovably) beasts. Understanding the cause of your dog’s diarrhea will help you (and their vet) help them. There are several potential reasons a dog might have diarrhea, including:

  • Ingesting something toxic. Some foods (such as chocolate and garlic), plants, and household items are toxic to dogs. However, your pup doesn’t know that, and curiosity and their natural food drive might get the best of them.
  • Diet changes. If you recently changed your dog’s diet, their stomach may have trouble adjusting. Go slowly.
  • Food intolerances or allergies. Sometimes, a dog is allergic to their food. Other times, the food may be too hard on their stomach, even if no allergy is present.
  • Bacterial infections. Infections like salmonella can cause diarrhea in dogs.
  • Viral infections. Pups can get coronaviruses, too. These infections, along with others like parvovirus, can trigger poop problems.
  • Parasitic infection. Other parasites, like hookworm and ringworm, can invade a pup’s body and affect the stomach, including causing diarrhea.
  •  Stress. Has stress ever caused your stomach to feel like it’s in knots? Ditto for dogs. Remember, dogs can get emotional, too. Stress from travel or even a trip to the vet might upset their tummy.
  • Reactions to medications. If a dog is having trouble tolerating a medication, their body might show you through their poop.
  • Inflammatory bowel disease. Like humans, dogs can experience inflammatory bowel disease, and loose stools are a red flag.
  • Organ dysfunction. In more severe cases, a dog’s diarrhea can be a symptom of kidney and liver disease.
  • Cancer. Sometimes, poop can be a flag your dog has cancer, including in the stomach.
golden retriever looking sad lying on the floor
Bruno Cervera / Pexels

What to do if your dog has diarrhea

The good news is that diarrhea often resolves and has a mild cause. While the issue can be gross and uncomfortable, the prognosis is generally good. However, as you can tell, there are many reasons for doggie diarrhea. Only your dog’s vet can diagnose the cause of the diarrhea. If the regular veterinarian can’t, they can refer you to someone who can. You should always feel comfortable calling your dog’s vet — they’re here to help. However, you’ll want to get a professional on the line if your pet’s diarrhea hasn’t cleared up in two days. Additionally, call a vet if the diarrhea is accompanied by:

  • Blood in the stool
  • Black or tarry poop
  • Vomiting
  • Lethargy
  • Lack of appetite lasting more than two days or a refusal to drink water

Your dog’s vet can run tests, including bloodwork and x-rays, to determine the cause of the diarrhea and help your pet get back to normal. Common treatments include medication, a bland diet, and food switches.

A black and white dog outside
Dids / Pexels

Closing thoughts

Dogs get diarrhea for many reasons, and the issue is often treatable with diet and medication. Common causes of diarrhea in dogs include infections, consuming something toxic, food intolerances and allergies, and inflammatory bowel disease. Sometimes, diarrhea can be a sign of something more severe, like cancer.

You should feel comfortable calling your dog’s veterinarian with any concerns. However, you’ll want to get the vet on the line if a dog’s diarrhea hasn’t improved after two days. A vet can take bloodwork and x-rays to find the precise cause of your pet’s poop problems and prescribe the correct treatment.

Editors' Recommendations

BethAnn Mayer
Beth Ann's work has appeared on healthline.com and parents.com. In her spare time, you can find her running (either marathons…
Why do dogs get eye boogers? What you need to know about this common problem (and when you should be concerned)
Eye boogers are rarely serious but sometimes can indicate an infection
Closeup of dog eye

Eye boogers: The truth is that we all get them. At least both humans and our canine companions. Nearly everyone will experience this at some point in pet parenthood (human parenthood as well, usually), and it's certainly nothing to worry about most of the time.

Standard eye discharge doesn't mean a dog eye infection, but the two can be linked. We'll go through when this isn't an issue and what to look for to figure out if there's more going on. Here's everything you need to know about puppy eye goop.

Read more
Why do dogs eat cat poop? And how you can get them to stop
These tips will stop your pup from eating cat doo-doo
Dog wears a yellow sweater and looks at the camera

Sometimes you might think you hear your cat using their potty, but when you go into check, it's actually the dog eating cat poop. Gross! While it seems pretty revolting to us, dogs sometimes eat poop, the feline variety included. Coprophagia, which means eating poop, shows up reasonably frequently in pups, and certain diets, environments, and even breeds can make this act more likely (research says hounds and terriers are the groups most likely to chomp poop, in general).

So why do dogs eat cat poop, and what should you do about this behavior? Read on for a few things to check and a couple of tips to prevent this extra meal.
Why do dogs eat cat poop?
Theories abound, but it turns out lots of different mammals eat poop, their own and others'. One possibility is that not all nutrients fully digest when they go through our systems, which means there are plenty of vitamins to have by consuming feces. Sometimes, these cravings result from a nutrient-deficient diet that is easy to fix by changing up your dog's food.

Read more
Why does my dog follow me to the bathroom? (It’s not as weird as you think)
Your dog has a reason for this behavior
A Yorkshire terrier sits in the bathroom and is seen reflected in the hallway mirror

If you're wondering, "Why does my dog follow me to the bathroom?" -- you're certainly not alone. Most pet parents are used to having a four-legged shadow no matter what room in the house they're in, but making eye contact with your dog while you're on the pot can feel a little bit strange. So what's behind this canine behavior, and is it a bad thing?

We've looked into this funny phenomenon and what it means to your dog, and it turns out that it's not as strange as you think. Remember -- your pup has a very different way of viewing the world, so while having company in the restroom may seem odd to you, your dog doesn't think twice about it.

Read more