Why Does My Dog Have Diarrhea? Common Causes and What You Can Do

Dealing with diarrhea is one of the less glamorous parts of pet ownership, but it’s also one of the most common reasons dog owners reach out to their veterinarian. Whether it’s a one-time accident or a sudden mess in the middle of the night, it can leave you wondering: what went wrong?

At Two Rivers Veterinary Hospital, we see dogs with diarrhea nearly every day—and while it’s rarely fun, it can be manageable. Let’s take a look at the most common causes and what you can do to help your dog at home.

Common Causes of Diarrhea in Dogs

1. Gastrointestinal (GI) Parasites
   Even dogs that spend most of their time indoors can contract intestinal parasites from contaminated soil, water, or even sniffing at another animal’s feces. That’s why we strongly recommend a monthly parasite preventative like Simparica Trio, which protects against intestinal worms, fleas, ticks, and heartworm.

2. Dietary Indiscretion
   Dogs are scavengers by nature, and many have no shame in tipping over a trash can to find a snack. Ingesting spoiled food, bones, wrappers, or fatty scraps can lead to digestive upset—and a very unhappy digestive tract.

3. Overfeeding or Sudden Diet Changes
   Even too much of a good thing can be harmful. Overfeeding, sneaking extra treats, or switching foods too quickly can lead to diarrhea. When transitioning diets, do so gradually over 5–7 days to give your pet’s GI system time to adjust.

What Can You Do at Home?

If your dog is otherwise acting normally—eating, drinking, playing—mild diarrhea may be manageable at home. Here are a few simple tips to help firm things up:

• Add a Little Fiber:
  Mix ¼ teaspoon of psyllium husk into each meal (for an average-sized dog) for a day or two. Fiber helps bulk up and normalize stool consistency.

• Add a Probiotic:
  Supplementing with a dog-specific probiotic like Purina FortiFlora can help restore the balance of healthy gut bacteria.

• Use a Diarrhea Support Kit:
  Products like Proviable’s Diarrhea Kit offer a two-step system: a probiotic paste for immediate support and capsules to help rebalance gut health over time.

• Skip the Chicken and Rice
  While traditional, the “boiled chicken and white rice” diet is not a balanced option. White rice may actually increase inflammation in the gut. Instead, we recommend sticking to your dog’s regular diet if tolerated, or switching to a veterinary-prescribed bland but balanced diet like Hill’s Science Diet GI Biome.

When to Call the Vet

If diarrhea lasts longer than 48 hours, if your dog seems lethargic, is vomiting, or if you see excessive blood in the stool (more than just a few drops), it’s time to call us. Diarrhea can lead to dehydration and may be a sign of something more serious.

We’re always happy to talk you through next steps, and when needed, we’ll recommend diagnostic tests or medications to help get things back on track. If you're ever unsure, it's better to check in.

Your dog’s digestive health is important—and we’re here to help when things go south.