Dogs

Causes of puppy diarrhea and how you can help a puppy with an upset tummy

Taking care of a little new puppy is awesome… exhausting… and a little stressful, right? ☺️ There are so many things to keep track of – regular vet visits, vaccinations and deworming, potty training, removing shoes and other objects from your furry baby’s mouth… To make matters a even more complicated, many puppies suffer from puppy diarrhea.

The thing is, young puppies have an immature digestive and immune system, which makes them naturally prone to diarrhea and other digestive problems. 

So if you have a new furry family member, be prepared for a few smelly days, because chances are that these days will come sooner or later 🤷‍♀️ 🙂

And if your pup is currently having a digestive problem, don’t worry, I’m here to help you better understand what’s going on, how you can help a puppy with diarrhea, and when it’s time to call your vet. 


While I am a veterinarian, this article is not intended to replace professional veterinary advice. If you have any medical concerns about your pet, consult your vet immediately. Always seek professional assistance if you are unsure of your pet’s health.



This post may contain affiliate links, which means I may receive a commission, at no extra cost to you, if you make a purchase through a link. Please see my full disclosure for further information.


small puppy lying on the floor

Understanding diarrhea in puppies

Diarrhea is a common condition characterized (as you sure know) by frequent, watery bowel movements. It results from disturbances in the gastrointestinal system, where the balance of water absorption and secretion is disrupted.

It can be triggered by various agents, such as infections, dietary intolerances or even stress. The irritant or infection compromises the gut’s ability to absorb nutrients and water efficiently, leading to the rapid movement of food through the digestive tract and loose stools. 

Usually, the immune system of the animal is strong enough to handle these agents. It’s an intricate play between pathogen invasion, immune response, and the physiological defensive mechanisms.

However, puppies have immature immune systems, which make them less capable of combating these disruptions. That’s the main reason why are puppies susceptible to more frequent and severe episodes compared to adult dogs. 

Diarrhea is not a disease per se, it’s a symptom of an underlying pathofysiologal process. Prolonged or chronic diarrhea can lead to dehydration, electrolyte imbalances, loss of appetite, weight loss and even death.

The most common causes of puppy diarrhea

I said before, you need to understand that diarrhea is a symptom, not a disease. Puppies, with their developing digestive and immune systems, are particularly vulnerable to various factors that can disrupt their gastrointestinal health. The signs might range from mild cases of an upset tummy to potentially life-threatening conditions. Knowing and addressing the root causes is essential in choosing the right therapeutic approach. 

We can divide the most common reasons of puppy diarrhea into 8 different categories:

  • diet change
  • food intolerance
  • stress
  • bacterial infection
  • viral infection
  • intestinal parasites
  • ingestion of foreign bodies or toxins
  • anatomical malformations in colon or rectum

Let’s talk more about the most common ones:

Intestinal parasites

Some puppies are already born with parasites. Others pick them up from their environment. Parasitic infections are one of the most common causes of diarrhea in puppies. 

Regular deworming is an important part of pet care, especially for young animals. Your vet will make you a deworming plan tailored to your pup’s specific needs. Please follow it.

! Many pet parents are not aware of this, but you can get parasites from your dog. That’s why is proper parasite treatment really important, especially if you have small children. I’ve written an article about diseases you can catch from your dog. Please read it, especially if you have kids or older people in your family, or if you are pregnant 🙂

Diet change

In young animals, the gastrointestinal tract is still developing, making them sensitive to changes in their diet. A sudden change in what they eat can disrupt their digestive balance, often leading to diarrhea. 

To minimize this risk, transition your puppy to a new dog food gradually, over a period of at least 5 to 7 days. Start by mixing a small amount of the new food with the old, gradually increasing the proportion of new food each day. This slow transition helps your pup’s digestive system adjust without causing a health problem.

It’s also the reason why giving your puppy table scraps is not a good idea.

Bacterial or viral infection

The digestive and immune system of young animals is still sensitive and underdeveloped. That’s why they are more susceptible to various bacterial infections. 

E. coli, Salmonella, Clostridium, and other bacteria can cause more serious illness, often accompanied by other symptoms such as fever, vomiting, apathy…

Perhaps the most dangerous causes of diarrhea in puppies are viral infections, which is why they require immediate veterinary care. Canine parvovirus and canine distemper are life-threatening conditions that need rapid medical intervention. Both are also potentially fatal in non-vaccinated or partially vaccinated animals.

Food intolerance, food sensitivity and food allergies

Some puppies develop intolerance or sensitivity to certain proteins in food. Identifying and managing food intolerances is a complex process that involves tracking food intake and symptoms. If you think that your puppy might be reacting to certain foods, talk to your vet. This is a complicated issue and you will need the help of a professional to manage it properly. 

Stress-induced diarrhea

Sometimes the stress of adjusting to a new home, new people… can be the trigger. Stress in dogs, just like in humans, can and often does manifest as diarrhea.

Ingestion of foreign bodies or toxins

When puppies ingest foreign objects or toxins, the situation can quickly become critical, necessitating immediate veterinary care. These items can obstruct their digestive tract or poison their system. 

Consuming spoiled food from the garbage is a common culprit behind digestive upset in puppies. Such food is often contaminated with harmful bacteria and toxins that disrupt the delicate balance of their gastrointestinal system, leading to symptoms like vomiting and diarrhea. 

Please monitor what your puppy eats and to keep potentially dangerous items out of reach 🙂

Here’s a list of human foods that are toxic to puppies and what a list of alternative healthy snacks

What to do if your puppy has diarrhea

If your puppy is playing, drinking enough water, seems generally happy and the diarrhea doesn’t last more than 12- 24 hours, you should be fine. However, since diarrhea is such a broad general symptom, I would recommend calling your vet and letting him decide.

Please see a vet immediately if your pet shows any of the following symptoms:

  • profuse, severe diarrhea
  • bloody diarrhea
  • yellow, green or dark brown diarrhea
  • black stool
  • vomiting
  • pale gums
  • lethargy (pup doesn’t want to play, just want to sleep or lay down…)
  • signs of discomfort or pain
  • doesn’t drink water
  • isn’t vaccinated or hasn’t received all their vaccinations
  • isn’t dewormed
  • might have swallowed a foreign body
  • might have swallowed toxic substances (toxic plants, rat poison…)
  • has a diarrhea that’s been going on for more than 1-2 days

If your pup is showing any of the above mentioned signs, please take them to a vet clinic. You can also bring a stool sample, your vet will need it for diagnostic tests. 

Bloody diarrhea in puppies

Bloody diarrhea is always a reason to bring your puppy (or your adult dog) to a vet clinic as soon as possible. The causes can be different – parvovirus, bacterial infection, hemorrhagic gastroenteritis… It needs further diagnostic and immediate treatment.

Infographic, puppy diarrhea - why does puppy stool color matter

How to help a puppy with diarrhea

Since puppy diarrhea is a symptom, treatment depends on the cause. 

What I need to highlight first – please never give your dog human medications.

Puppies with mild intestinal distress caused by abrupt change of food or stress can profit from a special veterinary diet for gastric problems or home-cooked bland diet (for example plain-cooked white rice). If you want to cook for your puppy, talk to your vet about proper recipes.

You might have read about letting your dog fast for one or two days. While it can be a helpful method for adult dogs, I don’t recommend it for puppies without getting your vet’s approval first.

Fresh and clean water is very important. Just like babies, puppies are prone to dehydration. Dehydration can lead to collapse and is potentially life-threatening. So make sure your pup is drinking enough. If not, please contact your vet.

If you suspect your puppy has a food intolerance, make an appointment with your vet. He might discuss with you the possibility to run an elimination diet to determine which proteins are problematic.

As mentioned before, in case of infections, parasites, or toxin ingestion… you need to take your puppy to a vet for proper diagnostics. Depending on the cause the treatment will vary from parasite management, antibiotics, and medications to surgery or hospitalization.

In all cases, I would recommend a few days of rest. No long walks, no long and/or rough play… that tiny body is dealing with health issue and needs a bit of rest. I know it’s extremely hard to force an otherwise healthy playful rumbustious puppy to rest. Maybe you can try to switch to mental stimulation. Instead of a long walk, you can try to teach him a few new commands 🙂

How to prevent diarrhea in dogs and puppies

Puppies are naturally prone to digestive sensitivities due to their immature and underdeveloped digestive system. However, here are a few tips that might help prevent upset stomach and bowel problems:

  • vaccinate your puppy at appropriate ages 
  • have proper parasite management and prevention plan right from the start
  • if you have house plants – google if some of them are poisonous
  • transition your puppy to a new diet slowly (over at least 5 days)

Diarrhea is the body’s response to some problem, it’s a signal that something is wrong. Observing your dog’s bowel movements is one of the best ways you can monitor your pet’s health ( I know, I know, but I stand by this statement 😃 )

In any case, it’s better to play it safe and contact your vet if your puppy has any bowel problems.

If you cannot take your pup to a vet, but still want a professional opinion, you can talk to a licensed vet via Vetster👇☺️

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So, that’s all from me. Happy pet parenting! ❣️🐾

If you have a new puppy, check my printable puppy planners in my shop ☺️

cute printable puppy planner

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