Diarrhea is one of the most common problems that can pop up for dog parents. While most dog diarrhea cases are acute and resolve on their own, it could also be chronic diarrhea and warrant vet attention.

If you’re asking, “Why does my dog have diarrhea?”, you’re asking the right question. Determining the cause and severity is how to decide if your dog needs to see a veterinarian or not. 

Why Does My Dog Have Diarrhea – 7 Common Causes

Pinpointing the cause of a dog’s diarrhea can be difficult due to the fact there are so many common causes, but here are some of the most likely.

1. Dietary Problems

Not all diets agree with all dogs. Some dogs don’t do well on a high-fat diet (such as dogs with pancreatitis), for example. If your dog has diarrhea, the best place to look and make changes is often their core diet.

This is also true if you’ve switched their food recently. Switching a dog’s main diet abruptly is usually a bad idea, and you should always transition your pup slowly to a new diet. If you’ve moved too quickly, start mixing more of their old food in and gradually increase the amount of new food. 

It could also be a temporary dietary problem that causes diarrhea in dogs, like too many treats in one day. If you notice diarrhea happening after exceeding your dog’s usual treat amount, forego treats for a day or two. 

Breaking treats in half in the future for rewards can prevent you from overdoing it. 

2. Allergies

While food allergies affect just 0.2% of dogs, those allergies can be to very common things—for example, a protein like chicken.

If your dog has diarrhea that just isn’t resolving and seems to have no cause, try moving them to specifically formulated dog foods for a sensitive stomach or having them tested for allergies by the vet. 

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3. Viral Infections 

Contagious viral infections can move from dog to dog, infecting your pup and causing symptoms like gastrointestinal upset—often showing as diarrhea in dogs. These range from relatively harmless viruses that will clear up on their own to extremely dangerous illnesses like parvovirus, which kills 10% of adult dogs it infects.

If your dog has played with other dogs recently, ask the owners if their dogs are exhibiting the same symptoms. If they are, this is a big sign the diarrhea may come from some sort of virus, and it’s a good idea to see your vet to rule out the particularly nasty ones. 

4. Parasites

Parasites are another common cause of a dog’s diarrhea. Gastrointestinal parasites that may cause diarrhea include:

• Roundworms
• Hookworms
• Whipworms
• Tapeworms
• Flukes
• Giardia

These can pass from dog to dog by drinking the same water or ingesting some feces (which, while it sounds gross to us, is very common in dogs). Fortunately, most parasites are cleared up with dewormer, though it’s important to ensure you’ve cleaned and disinfected anything they’ve touched in the house or you may be in for another bout of dog diarrhea.

Your vet may also recommend a second round of dewormer to ensure all of the parasites are truly gone from the environment. When you see healthy poop, it’s usually a sign they’ve cleared up.

5. Stress and Anxiety

Stress is one of the biggest causes of diarrhea in dogs. It causes the large intestine to become inflamed, which then causes the diarrhea.

Stress and anxiety can happen for any reason, and some more nervous dogs could be more prone to it than others. Changing environment is one common reason a dog might become stressed—for example, a new puppy who’s arrived at a brand new home, or a dog who’s been boarded for a week and felt out of their element.

When diarrhea is caused by stress and anxiety, it usually resolves on its own. Create a calm environment for your pup and try to limit anything that might exacerbate that anxiety. 

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6. Ingesting Toxins

Ingesting toxins or poisons can also cause diarrhea in dogs. Many things that seem innocuous to humans are poisonous to dogs, including:

• Grapes
• Garlic
• Onions
• Xylitol, an artificial sweetener
• Chocolate

Dogs often get their paws on these because a well-meaning but uninformed human hands them a toxic treat or because they nose-dive into the trash on walks before their owner can stop them! 

If you know your dog has recently gotten into a toxin and you’re seeing dog diarrhea, it’s time to visit a veterinarian. 

7. A Blockage

Lastly, the cause of diarrhea could also be a painful blockage. It may seem counter-intuitive but If your dog has partially blocked intestines, then the only thing to be expelled is liquid poop. 

If you ever suspect a foreign body, seek the nearest emergency vet, as these can be life-threatening. 

When to Visit Your Vet

Since diarrhea in dogs is generally mild, sometimes it’s difficult to know when it’s time to get your dog in the car and drive to the vet’s office.

Experts recommend that if diarrhea lasts for two days or more, it’s time to visit the vet because of the risk of dehydration, but this isn’t a hard and fast rule. There may be other times when it’s clear you need to go to the vet sooner.

For example, the diarrhea may be coupled with more severe symptoms, like vomiting, lethargy, or a lack of appetite. In this case, the underlying cause of the diarrhea is likely something more serious than stress or anxiety, and a vet should take a look just in case. 

You should also see a vet right away if the diarrhea has blood in it, as this is another underlying sign something is wrong. If your dog is clearly in pain or collapses, it’s time to find the nearest emergency animal hospital. 

How to Treat Diarrhea in Dogs

Many times, diarrhea in dogs can be treated at home if it’s an acute case that doesn’t last more than two days and doesn’t have any other symptoms (but if it’s chronic diarrhea, it’s another story).

Experts recommend feeding a bland diet of boiled chicken and plain cooked white rice to treat diarrhea in dogs. This gives the dog’s stomach a chance to reset without adding too many ingredients to it. If your dog has ever shown signs of an allergy to any of these foods, however, you should forego this option.

Adding a tablespoon of canned plain pumpkin is a great way to firm up your dog’s poop because it’s a good source of fiber.

Additionally, adding natural yogurt to the bland diet can also help because it contains natural probiotics which help to rebalance the dog’s gut biome.

Make sure they get plenty of fluids too and encourage them to drink where possible. Because watery diarrhea forces fluids and food to move through the system quickly, it runs the risk of dehydrating your dog, which can make symptoms much worse and can quickly become dangerous. 

Never give them human medications, as these aren’t formulated for dogs and could also make things worse. 

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Final Thoughts

None of us like to see our dogs get sick, so seeing diarrhea in dogs can be alarming. Fortunately, the vast majority of cases are mild diarrhea and usually resolve on their own with plenty of hydration and love at home.

But if diarrhea lasts for more than two days or comes with other, more severe symptoms, it’s time to see your veterinarian to address the deeper underlying cause and get your best friend back to normal.