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Can Probiotics Cause Diarrhea in Dogs? A Vet Explains

Wondering, “can probiotics cause diarrhea in dogs?” The answer is yes – diarrhea is a common, usually short-term reaction to probiotics for dogs. A vet explains the link between dog probiotics and diarrhea, and what to do if your dog is effected.

5 min read·Updated: May 29, 2025
Can Probiotics Cause Diarrhea in Dogs? A Vet Explains

Probiotics aren’t just good for people. They’re good for dogs, too! Probiotics offer numerous benefits, including improved dog gut health, reduced sensitivity towards allergens, and enhanced immune system support.

However, as with any dietary change, introducing probiotics to your dog’s daily routine can lead to discomforts like diarrhea. These reactions are typically short-term, while your dog’s microbiome adjusts to the additional healthy bacteria.

If your vet has recommended probiotics for your dog, it’s beneficial to know how probiotics can cause diarrhea and what you can do to manage it.

Can Probiotics Cause Diarrhea in Dogs?

In a word, yes. Gut health is complex and tightly regulated. Adding anything new to the diet, even something beneficial like probiotics, can, at least temporarily, disrupt that regulation and cause short-term reactions.

For dogs just starting on probiotics, mild diarrhea occurs commonly as the digestive system adjusts to the dietary change. Probiotics can also cause loose stools in dogs. 

Why Does This Happen?

To understand why this happens, we need to review some basics about the gut microbiome. A dog’s gut microbiome is the environment within the gut that contains billions of microorganisms, including bacteria, fungi, and viruses. A healthy gut microbiome is crucial not only for good digestive health but also for health in other body systems, such as the immune system.

The beneficial bacteria in the gut, known as probiotics, are critical for a healthy digestive function. They also help to maintain a healthy and well-balanced gut microbiome.

However, an upset stomach and other digestive problems can disrupt the delicate balance within the microbiome and cause an imbalance. Stress or environmental changes can also disturb this balance by affecting the population of beneficial bacteria in your dog’s gut.

Probiotic products help maintain the population of good bacteria in the gut. However, this process can temporarily upset normal digestive functions, which can lead to short-term diarrhea and loose stools.

Although diarrhea with probiotics is common, several factors influence its development:

  • Your dog’s sensitivity to probiotics
  • Specific probiotic strains in the product
  • The amount of probiotic powder or the number of chews your dog receives 
  • How frequently you give your dog probiotics

There are no breed predispositions to probiotic-associated diarrhea.

Can probiotics cause diarrhea in dogs?  The answer is yes - diarrhea is a common, usually short-term reaction to probiotics for dogs. A vet explains what to do.

Should You Worry About Dog Diarrhea From Probiotics?

In many cases, probiotic-associated diarrhea is mild and temporary, and not a cause for concern. You won’t enjoy cleaning up the diarrhea, of course, but it won’t last long.

However, if the diarrhea persists and your dog is visibly uncomfortable and unwell, contact your veterinarian. Diarrhea that persists for more than two days can lead to other health issues, such as dehydration, so it is essential to treat the diarrhea promptly.

What To Do if Your Dog Has Diarrhea After Starting Probiotics

If your dog develops diarrhea after starting probiotics, monitor your dog’s behaviors and contact your vet. Provide your vet with this information:

  • When you started giving your dog the probiotics
  • How much probiotic product you are giving your dog, and how often (e.g., once daily)
  • Probiotic strains in the product
  • When the diarrhea started
  • Any other behaviors (e.g., lethargy, eating less)

Your vet will advise you on whether you can manage the diarrhea at-home or if professional veterinary care is needed. At-home hacks include a continuous supply of fresh water and a bland diet, such as boiled and unseasoned chicken and rice.

They may also advise you to discontinue the probiotic until the diarrhea resolves. Lowering the dose may also be appropriate, but your vet will advise you on this.

Other Potential Discomforts Related to Dog Probiotics

Here are some other potential discomforts that can be related to probiotics for dogs:

  • Gas
  • Constipation
  • Interaction with medications
  • Allergic reactions (rare)

Tips for Giving Your Dog a Probiotic Powder or Chew

First things first: consult your veterinarian about whether to add probiotics to your dog’s diet. Your vet can recommend high-quality probiotic products for dogs that minimize the use of artificial ingredients and contain multiple strains of probiotics.

Follow your vet’s usage instructions. The recommended amount of probiotics to give to dogs is 1 to 10 billion colony-forming units per day. Dogs that are initially given more than this may be more prone to developing diarrhea.

Generally, probiotics should be given with food to support digestion, but dogs with digestive issues may need to take probiotics between meals. Your vet will advise you on whether to give your dog probiotics with or without food.

Introduce probiotics to your dog’s diet gradually, for example, starting with a very small amount. It takes a few days for the probiotics to colonize and populate within the gut, so you don’t want to give your dog too much, too fast, before their gut is ready for it.

Probiotics are available in several formulations, including powder and tablets. You may need to try a few formulations before finding one that your dog prefers, so be patient as your dog decides what they like.

Finally, monitor your dog for any odd behaviors, keeping a close watch for any signs of diarrhea. If diarrhea develops, contact your vet.

JoAnna Pendergrass, DVMJ
Written by

JoAnna Pendergrass, DVM

JoAnna Pendergrass, DVM, is a veterinarian and freelance medical writer. As the founder and owner of JPen Communications, JoAnna is passionate about working with companies like PetLab Co. to educate pet parents and empower them to make informed health decisions for their pets. Since 2016, she has written hundreds of articles on a variety of topics in pet care, including behavior, wellness, and nutrition. In her free time, JoAnna enjoys playing the viola, baking, and seeing the world through the eyes of her fearless toddler.

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The information contained within this site is not intended as a substitute for professional medical or veterinary advice. PetLab Co. is not intended to diagnose, treat, cure or prevent any disease. If your pet has, or you suspect your pet has any medical condition, you are urged to consult your veterinarian. Medical conditions can only be diagnosed by a licensed veterinarian. These statements have not been evaluated by the Food and Drug Administration. Results May Vary. Not intended for human consumption. Please consult your veterinarian regarding any change in treatment or supplementation.
*In Amazon Pet Health Category in 2022
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