Why Your Puppy Has Diarrhea & What To Do About It


Why Your Puppy Has Diarrhea & What To Do About It

Puppies can get diarrhea for a variety of reasons, some harmless and easy to treat and others more sinister. Mild cases can be managed at home, but here’s how to know if a puppy with diarrhea should be seen by a veterinarian.
By Kate Eldredge Basedow, LVT August 24, 2020 Advertisement Pin FB More Tweet Email Send Text Message Print

Even a healthy puppy will probably experience diarrhea at one time or another. Puppies do not have fully functioning immune systems, so they can be a little more sensitive to changes and potential sources of infection than their adult counterparts. Mild cases of diarrhea may go away quickly on their own, but other causes can be a sign of a serious problem. Here's what to watch for and how to know what your next steps should be when your puppy has diarrhea. 

sad looking french bulldog puppy
sad looking french bulldog puppy Credit: Rebecca Nelson / Getty

Why Does My Puppy Have Diarrhea?

Some of the most common reasons for puppies to have diarrhea include:

  • Stress
  • Diet change
  • Parasites
  • Dietary indiscretion
  • Toxicity
  • Bacterial infection
  • Viral infection


While being a puppy can be a lot of fun, there are also a lot of new experiences—and that can be stressful. Moving into a new home, meeting new people and animals, learning to walk on a leash, vet visits and vaccinations, that first encounter with the Roomba. All of these experiences can cause stress, and your puppy may get diarrhea because of that. Diarrhea related to stress usually occurs within hours to a day of the stressful event, and generally resolves quickly on its own. 

Diet Change

Changing foods too quickly can cause diarrhea no matter what your dog's age is. Ask your puppy's breeder or previous owner what brand and formula of food she is used to eating, and start off by using that same diet. If you want to switch to a different food, do it gradually over several days, starting with just a little of the new food mixed in with the old and increasing the ratio of new food over time.

Some dogs may have food intolerances or, less commonly, allergies to specific ingredients. These can also cause diarrhea. Identifying a food allergy or intolerance is a time-consuming process and will require guidance from your veterinarian.


Worms love puppies! Some common parasites that can infest puppies include roundworms, hookworms, whipworms, tapeworms, coccidia, and giardia. Parasites are most commonly transmitted through poop (a dog with worms poops out eggs and/or larvae, a puppy sniffs poop and inhales them). But some, such as roundworms, can be transmitted from mother to puppies through the placenta.

As well as having diarrhea, puppies with parasites may have distended bellies, bloody diarrhea, appear thin, or be lethargic. Sometimes you may be able to see worms in the poop.

Your veterinarian can check your puppy's stool for worm eggs and other parasites. Always bring a sample along if your puppy is having diarrhea. Once the offending parasite has been identified, your vet can prescribe the best deworming medication to resolve the issue. 

Being treated for worms or other parasites does not prevent your puppy from getting them again, however. Remember how parasites are often spread through poop? Be sure to thoroughly clean your yard, removing all poo to minimize the number of parasitic worms living in the soil and environment. Otherwise, your puppy can reinfect herself from her own poop.

All puppies should be on a regular deworming schedule starting while they are with the breeder. Most veterinarians recommend continuing regular, long-term deworming, such as with a monthly product.

Dietary Indiscretion & Toxicities

Like toddlers, puppies love to put their mouths on anything and everything. Eating the wrong thing can cause diarrhea in a couple of different ways. "Dietary indiscretion" is a common veterinary diagnosis, and simply means that your puppy ate something that she shouldn't have. This could range from feasting on the garbage leftover from your cookout to swallowing a chewed-up tennis ball or munching on your amaryllis plant. 

Eating an excessive amount of rich or fatty foods can cause stomach upset. In cases like these, your puppy may vomit or appear uncomfortable as well as having diarrhea. 

If your puppy has eaten something toxic, exact symptoms will vary depending on what and how much she ate. If you suspect your puppy has eaten something toxic, or are unsure about the potential threat of her illicit snack, contact an animal poison helpline such as the ASPCA Poison Control Center or the Pet Poison Helpline, (855) 764-7661, immediately. These services do charge a fee, but it's well worth it to have access to the most up-to-date information on toxicities in dogs. 

Even nontoxic non-food items can be problematic if they get stuck in your puppy's gastrointestinal tract and cause a blockage. Besides having diarrhea, a puppy with an obstruction may vomit, be lethargic, refuse to eat, and/or have abdominal pain.

Viral & Bacterial Infections

Parvovirus, often referred to as simply "parvo," is a diagnosis that strikes fear in any puppy owner's heart. This virus is highly contagious and wreaks havoc on your puppy's immune system and body, causing severe diarrhea, vomiting, weight loss, anorexia, fever, and lethargy. Treatment consists of supportive care to help your puppy fight the disease and target symptoms. A puppy with parvo will likely be admitted to the hospital for intravenous fluids (to keep her hydrated), medications, and round-the-clock supervision from her veterinary team. Parvo is often fatal, especially if treatment is started too late.

Thankfully, there is an effective vaccination for parvo, and it is included in the routine puppy series. Your puppy will receive several rounds of the vaccine depending on her age. It's essential to get your puppy to her booster appointments on time; even one missed vaccination can leave her unprotected. Once she has finished her puppy series, the following year she can either get a one-year or three-year vaccine. 

Avoid places with other dogs, such as dog parks, boarding kennels, and popular dog-walking spots until she is fully vaccinated. Only allow her to interact with dogs that you know are vaccinated. If your puppy does get parvo, she will need to be kept away from unvaccinated dogs and puppies to prevent spreading it to them.

Besides viruses such as parvo, your puppy can also get bacterial infections in her G.I. tract that can cause diarrhea. Common culprits include Clostridium, E. coli, and Salmonella. Your puppy can pick these up from eating rotten food or poop from an infected animal. As she matures and her immune system finishes developing, she will be less susceptible to these tiny invaders.

Vomiting & Diarrhea

Vomiting and diarrhea are a dangerous combination. Both cause your puppy to lose water from her body, leading to dehydration. Dehydration can cause permanent damage to her internal organs in a matter of days. If your dog is experiencing this one-two punch of vomiting and diarrhea, you'll want to call your vet right away. 

When to Call Your Vet

If your puppy has just had a couple bouts of loose stool and is otherwise happy and doing great, there is no need to panic. It will likely resolve on its own.

Signs to call your veterinarian to schedule an appointment:

  • Diarrhea that lasts more than a day
  • Bloody or black stool
  • Vomiting and diarrhea
  • Lethargy
  • Pale gums
  • Fever (normal for a dog is 100 to 102 degrees Fahrenheit)
  • Painful behavior—hunched posture, tense, or crying out
  • Known ingestion of a non-food item (such as hair ties or toys) or a toxic substance


If your puppy is overall healthy, your veterinarian may simply instruct you to feed a bland diet (such as plain boiled chicken, plain cooked hamburger, or rice) for a few days to give her digestive system a break. Probiotics intended for use in dogs can also be beneficial.

Your vet may also prescribe a medication such as metronidazole, tylosin, or Endosorb to help normalize the G.I. tract and stop the diarrhea. 

If your puppy is also acting ill, exact treatment will depend on the symptoms and cause of the diarrhea. She may be given fluids under the skin to help keep her hydrated.

Preventing Puppy Diarrhea

There are several things you can do to minimize the risk of your puppy having diarrhea:

  • Make diet changes gradually over several days
  • Avoid feeding table scraps
  • Follow a regular deworming schedule
  • Pick up all dog poop promptly
  • Keep your puppy crated when unsupervised to prevent her from eating something she shouldn't
  • Keep human foods out of reach
  • Only use dog-friendly plants in your yard and keep toxic houseplants out of reach
  • Don't skip or delay any part of the puppy vaccination schedule
  • Avoid unvaccinated dogs until your puppy is fully vaccinated
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