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Ask the Vet: What Causes Diarrhea in Newborn Puppies?

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Causes of Diarrhea in Newborn Puppies

What causes diarrhea in newborn puppies? Your puppies can be affected by a variety of different causes, from simple indigestion to the rather lethal parvovirus. The most common cause of diarrhea in puppies tends to be intestinal parasites. The worry with any of these causes is that it's incredibly easy for your puppy to become dehydrated, making a minor illness something that can rapidly grow detrimental. When your puppy has diarrhea, especially if it lasts for more than a day, it's crucial to get them seen by a local veterinarian to be diagnosed and treated. Following are several potential causes of diarrhea in newborn puppies.

What Causes Diarrhea in Newborn Puppies?

Diarrhea in newborn puppies

Diarrhea in newborn puppies can be due to parasites.

Intestinal Parasites

Your puppy can get intestinal parasites from just about anywhere. One of the most common types are roundworms, which can be transmitted through their mother's milk, across the placenta, and from the environment.

If one puppy gets them, it's easy to share with the others. Other types of intestinal parasites are also possible, including hookworms and Coccidia. Less commonly in newborn puppies, you can also see whipworms and Giardia affect them.

Treatment for intestinal parasites involves diagnosing and treating the parasite appropriately. Pyrantel pamoate or Panacur are commonly used to deworm puppies prophylactically, and these can also be used to deworm against roundworms and hookworms. Other medications are needed to treat different parasites, such as Albon for Coccidia. Your veterinarian will need to run an intestinal fecal exam to diagnose these problems.


Dog Fear of Water

While your puppy is likely not eating anything but milk as a newborn, she can still develop diarrhea from the milk she's consuming. This cause of diarrhea is especially true if you're bottle feeding in addition to their mother nursing them.

Sometimes having a diet that's too rich causes a problem known as rapid transit stools, and some milk sources are harder to digest than others, such as giving newborn puppies cow's milk instead of puppy milk replacer.

Your veterinarian will likely diagnose the cause of diet-induced diarrhea after ruling out intestinal parasites and taking a careful history. Sometimes only one puppy is affected, especially if he's gorging on food. Limiting food intake or changing the source of the milk are ways to treat this diarrhea.


Viral and bacterial infections are both possible in newborn puppies. Bacterial infections often occur as bacterial overgrowth in their gut, secondary to a rich diet or dietary indiscretion.

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Viral infections can be especially dangerous and include parvo, which attacks rapidly dividing cells of the intestines and bone marrow. While only one puppy might get a bacterial infection, all are susceptible to viral infections, especially as newborn puppies.

Your veterinarian will likely treat a bacterial infection with amoxicillin, an antibiotic. While viral infections are not treated with antibiotics, your vet may prescribe them to help with secondary bacterial overgrowth. Viral infections typically need supportive care, with nutritional support and fluid therapy, often intravenously given. Your puppy will need critical support, or these infections can be deadly.

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Stress can give your puppy diarrhea and is often caused by changes in their routine or being exposed to new people or animals.

Traveling with your puppies is not recommended as stress can so easily affect them. Travel can also increase their risk of exposure to potentially deadly infections like parvo, distemper, or adenovirus.

Stress diarrhea is usually one of the easiest causes of diarrhea to treat. First, you'll want to make sure that your puppy's environment is calm and comfortable. You'll want them to have only milk or a prescribed bland diet.

They'll likely also need probiotics, which come in many forms, such as Fortiflora by Purina or BacPak Plus probiotics. Some cases will also need antibiotics to treat secondary bacterial overgrowth that occurs secondary to diarrhea from the stressful event.

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Dietary Indiscretion

When they're itty bitty, your puppies are likely not going to get into too much trouble, especially if they're contained in a whelping box. As they start to get more mobile, they're going to begin to put things into their mouths, from food and trash to toys and socks. All of this taste testing can upset their stomachs and cause diarrhea.

If your puppy might have eaten something harmful, get them to your veterinarian or local veterinary emergency center ASAP. If they might've gotten ahold of their mom's food, you can likely monitor them for a day, offering probiotics, as necessary. If you aren't sure if they got into something, it's best to err on the side of caution and have them evaluated. Small objects can cause obstructions in any puppy when eaten.

When to Worry?

puppy vet

It's hard to determine when you should really start to worry about your puppy's diarrhea. It's always better to be safe and have them evaluated by a veterinarian, but some episodes of diarrhea are require prompt attention.

These include bloody or dark, tarry stools or if your puppy is vomiting while having diarrhea. If your puppy is lethargic or not eating, you should also have them seen.

Another red flag for a problem is if your puppy has pale gums. Get them to a veterinarian immediately as bleeding or parvo could be a culprit.

Preventing Diarrhea in Newborn Puppies

There are several things you can do to help prevent diarrhea in newborn puppies. First of all, make sure that your female dog is dewormed properly prior to delivering puppies to minimize the risk that she will transmit parasites to the pups.

Try to limit the puppies exposure to other pets and outside environments while they are growing, until they're fully vaccinated. At the same time, make any diet transitions gradual and try to limit the stresses that they might encounter. If you know they are going to undergo a stressful period, talk to your veterinarian beforehand about possible probiotic options for them.

About the Author

Elizabeth Muirhead is a practicing veterinarian. She received an undergraduate degree in biological sciences before getting her doctorate in veterinary medicine. She has experience with a variety of household pets, from dogs to guinea pigs. She regularly attends international veterinary conferences to stay abreast of new information.

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