Puppy Diarrhea: Causes, Symptoms and Treatment

Dr. Jason Gagné, DVM, DACVIM
By Dr. Jason Gagné, DVM, DACVIM
Updated: 6/3/20242-4 minutes
A little puppy resting on a person’s knee

Puppy diarrhea can be unpleasant to deal with, especially when you’re trying to house-train your puppy. Aside from the difficulty for you, no owner wants to see their puppy suffer.

It can also be tricky to recognize when puppy diarrhea is a sign of something more serious that requires a vet visit, and when it can be easily dealt with at home. In this article, we provide information about puppy diarrhea, and give you practical advice on treating and preventing puppy diarrhea.  

Puppy Diarrhea Causes

If you’re dealing with this situation, you might be asking, Why does my puppy have diarrhea? There are several causes. A puppy’s stools will be a little soft while he is on a milk diet. As your puppy transitions to puppy food, his stools should firm up. But there may be times when his stomach gets upset and he gets diarrhea. 

If he has been fully weaned, there are several puppy diarrhea causes. Most of these are not serious and can be easily addressed to help your puppy return to normal stools. The most likely causes include: 

  • Diet change or food intolerance 
  • Stress 
  • Infections 
  • Parasites 

It’s not just a puppy thing—some of these items can also cause digestive upsets in adult dogs.

Because puppies are more fragile, it’s important to contact your vet if you see puppy diarrhea with blood or an unusual color, or it is accompanied by vomiting, lethargy, or dehydration.

Changes in Diet

A puppy with diarrhea may be struggling to adapt to a change in food. This normally happens when you first bring the puppy home and offer a different type of food than was offered by the breeder or the adoption facility. If possible, try to feed your puppy the food that was offered at his previous home, or transition to the new food gradually.

The other change in diet happens when your pup reaches one year old (depending on breed size). To avoid stomach upsets at this point, transition to the adult food over the course of seven to 10 days. Your veterinarian may also recommend giving your puppy Purina® Pro Plan® FortiFlora® probiotic supplement when starting these transitions (both to new puppy food and also to adult dog food) to help support the gut microbiome. 

Within a few days of transitioning to a new food, your puppy’s stomach should become used to the new food and the diarrhea should stop. If not, talk to your vet about other possible causes and if a new puppy food for sensitive stomachs and diarrhea is warranted.


Puppies are more likely to be stressed when they first come home. This is because they are in completely new surroundings and do not recognize the people around them. Stress can cause loose stools, but as your puppy gets used to his new home, he should become less stressed, and his diarrhea should clear up.

Bacterial and Viral Infections

Because a puppy’s immune system develops as they grow, it can be much more delicate than the immune system of an adult dog. This makes puppies prone to bacterial infections, like Salmonella, E. coli, and Clostridium, that can cause diarrhea. These serious illnesses are usually picked up from drinking contaminated or stagnant water, tick bites, or coming in contact with infected animals. Bacterial infections may be accompanied by other symptoms, such as loss of appetite, fever, vomiting, and bloody diarrhea.

If a bacterial infection is diagnosed, your vet will prescribe antibiotics. Unfortunately, antibiotics can also lead to diarrhea by upsetting the natural balance of your puppy’s gut microbiome. If that happens, ask your vet about a probiotic or prebiotic supplement to help restore the good bacterium in your puppy’s intestines.

A viral infection is more worrisome for puppies. Parvovirus or distemper are potentially fatal diseases that can affect unvaccinated or partially vaccinated puppies, and both require immediate veterinary care. Parvo symptoms include bloody diarrhea, lethargy, vomiting, fever, and abdominal pain and bloating. Signs of distemper include a cough, vomiting, diarrhea, fever, seizures, and lethargy. If you have a sick puppy or your puppy is experiencing these other symptoms with their diarrhea, see your vet as soon as possible. 


Dog parasites, like roundworms, hookworms, whipworms, coccidia, and giardia, can also cause diarrhea. Parasites are often found in unclean conditions, so keep this in mind when choosing a puppy to take home. They can also be passed on from mother to offspring when the puppy is very young, so if you suspect a parasite could be the problem, arrange a visit to the vet.

These are just some of the most common reasons for puppy diarrhea. There are many other possible causes, including viral infections and a change in water.

Puppy Diarrhea Color: Explaining Healthy and Concerning Colors

What does healthy puppy poop look like? Normal puppy poop should be brown in color. If your pup’s poop is one of the colors listed below in our puppy diarrhea color chart, see your vet as soon as possible. It can be a sign of a serious condition that may require immediate medical attention.

  • Puppy diarrhea streaked with blood – Indicates blood in stool. 
  • Puppy with black diarrhea – Usually indicates bleeding high in the stomach. 
  • Puppy with yellow diarrhea – Almost also a sign of bacterial imbalance in the bowel. With diarrhea, it may be related to coccidia
  • Puppy with green diarrhea – This could be mucous or if your puppy has eaten grass. 
  • Puppy with white diarrhea – Highly unusual color indicating too much calcium in the diet, a severe imbalance or infection in the bowel. 
  • Mucus – Yellowish, white, or clear slimy substance indicating bowel irritation. 
  • Brown with white spots – Likely this is a sign of intestinal parasites.

Use this handy puppy poop chart to check your puppy’s poop for color and consistency regularly.

To diagnose your puppy’s loose stools, your vet may take a stool sample to look for intestinal parasites, worms, or any signs of infection. They may even take an X-ray to look for other causes. Although it’s not very pleasant, it can also be useful to take a photo of your puppy’s diarrhea to show your vet.

Puppy Diarrhea Treatment

So, what do you feed a puppy with diarrhea? Your veterinarian can recommend a therapeutic puppy food designed to help settle their digestive system. Avoid giving treats, snacks, or human food. 

If your puppy’s condition does not return to normal or seems to worsen, you should let your vet know as soon as possible. Your vet may recommend different medicines that can help treat your puppy’s diarrhea and give you tips on how to hydrate a puppy with diarrhea.

For puppies that experience diarrhea on a regular basis, a diet specially formulated for sensitive stomachs may help. Pro Plan Sensitive Skin & Stomach Puppy Food contains a special combination of nutrients that support puppies with sensitive digestive systems. In addition to highly digestible ingredients, these formulae contain natural prebiotic fiber that nourishes specific positive intestinal bacteria that supports digestive health and helps maintain a good stool quality. If serious enough, your vet may also recommend that your puppy remain on the therapeutic food designed to help with digestive upset.

Can dehydration cause diarrhea in puppies? Not really; it’s the other way around—diarrhea and vomiting can cause dehydration. If your puppy is dehydrated, your vet may recommend a supplement to help in his recovery.

How to Prevent Puppy Diarrhea

How can you stop puppy diarrhea? Puppies and adult dogs will occasionally experience diarrhea. Most causes of diarrhea in puppies are very preventable, and there are a few steps you can take to avoid it happening again.

First, feed a consistent, puppy-specific diet that contains everything he needs. If you want to change his food, make sure you do it slowly over a period of several days. Second, always make sure you’re keeping on top of their regular deworming and flea treatments. Last, stay up-to-date with their puppy vaccinations and boosters as this can prevent certain infections and viruses that can be deadly. 

If you’re concerned about your puppy’s digestive health, the Petivity Microbiome Analysis Kit can analyze your pup’s poop and provide tailored nutrition and supplement recommendations. 

When to See a Vet About Puppy Diarrhea

If your puppy has diarrhea, it can be tricky to know whether you should bring him to the vet or treat him at home. However, there are number of signs you can watch out for. 

  • Is there blood in his poop? Blood in diarrhea is a sign that something else is wrong and should be taken seriously. If you see this, take your puppy to the vet as soon as possible. 
  • Is his poop black and tarry? If so, this could be the sign of a more serious problem, because it means there is digested blood in the intestines. It could mean there is some type of internal bleeding going on in their body. 
  • Is your puppy lethargic or not interested in food? This can mean he is fighting an infection and needs medication from your vet. 
  • Is your puppy vomiting, too? This can be a sign of a serious illness or that he ate something toxic. Your vet should be consulted. 
  • Is your puppy not eating? If he’s missed two feedings or gone 24 hours without eating, it may be a sign of a serious condition and you should contact your vet.

If your puppy has not displayed any of the above signs, it’s likely he doesn’t need to see the vet – unless the diarrhea is frequent or has lasted longer than 24 hours. However, you should always contact your veterinarian if you are concerned.

For more expert tips on the health of your puppy, explore our other puppy health articles.

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