Why Does My Dog Have Diarrhea?

By Chyrle Bonk, DVM November 15, 2019

One of the more dreaded doggy ailments is diarrhea. Few other issues have you getting up at different hours of the night, running to the door in hopes of getting your dog outside in time so that you don’t have to clean up the mess of all messes that is about to come. Diarrhea can be caused by everything under the sun, so it’s not always easy to prevent or treat. Since diarrhea is something that you will undoubtedly have to deal with as a dog parent, we’re going to get down and dirty with every messy detail.

What Is Diarrhea?

Simply put, diarrhea is loose or unformed stools. The stools generally occur in larger volumes with an increased frequency. Diarrhea is due to a faster than normal transit time of digested material through the intestinal tract, combined with a decrease in water and nutrient absorption. Diarrhea itself isn’t a disease, but rather a symptom of something else that could be as simple as eating something unpleasant to something as serious as cancer.

Is Diarrhea Common In Dogs?

If your dog is known for their scavenging abilities and dietary indiscretion, then diarrhea may be a fairly common issue for you. Diarrhea caused by eating something disagreeable should be short lived and typically without any other symptoms present. However, diarrhea that is bloody, persistent, or present with other symptoms such as lethargy, vomiting or a fever is not considered common and should be seen by a veterinarian.

How Do I Know If My Dog Has Diarrhea?

I’d like to say, “when you know, you know” to answer this question. However, the truth is that determining if your dog has diarrhea may not always be so easy. As we already discovered, diarrhea is defined as loose or unformed stools. So technically anything that doesn’t form that tubular shape that you’re all too familiar with should be considered diarrhea. But what about when a bowel movement starts out formed and then finishes with a splat? That’s why the second part of the description for diarrhea includes increased volumes and increased frequency.

If your pup is a pretty regular, twice a day kind of eliminator and suddenly jumps to four or five times a day, then suspect diarrhea. Also, if you’re used to picking up their piles with one hand and all of a sudden you have to enlist the help of both hands, then consider it diarrhea.

You may also notice other signs along with softer stools, including vomiting, lethargy, a decreased appetite, increased water consumption, or straining to defecate. For chronic diarrhea, weight loss may be noticeable. Diarrhea may also carry a particularly nasty odor that is associated with certain diseases like parvo. 

Why Does My Dog Have Diarrhea?

You’ve determined that your dog indeed does have diarrhea, now it’s time to figure out why. Diarrhea can come about due to many, many reasons, so figuring out the exact culprit isn’t always easy. Here’s a list of the most common diarrheal causes broken down into two categories: acute (sudden) and chronic (persistent).

Acute diarrhea is any change in feces that lasts no longer than two weeks and can be caused by the following:

  • Stress

Stress can really wreak havoc on all parts of the body, digestive system included. If you’ve just moved, gained a new furry roommate, or even a new tiny human, your dog may break with diarrhea. Diarrhea of this nature is usually short-lived once your dog’s stress levels go down. You can give them probiotics to help balance their unbalanced system and recover faster.

  • Garbage Gut

When your dog ransacks the garbage, consuming rotten food, scraps, and inedibles, it can throw their gut way off-balance leading to diarrhea. This diarrhea is usually self-limiting and clears up once the nasty culprits have cleared their system. Again, probiotics can help decrease the recovery time.

  • Sudden Food Change

If you’ve ever read the label on your dog food bag, you may have skimmed over a section on mixing old food with new food anytime you’re switching between brands, formulations, or even flavors. This is because your dog’s digestive system gets used to those ingredients and any sudden change can put things out of whack causing diarrhea. Always mix old food with new food and gradually switch your dog’s food over the course of about a week to allow their digestive system to adjust appropriately.

  • Infections

Viral, bacterial, and some parasitic infections can lead to acute diarrhea. Any of these illnesses usually present with other symptoms of vomiting, fever, lethargy, or inappetence as well. Be sure to see your veterinarian if any of these symptoms are severe or if they last longer than 48-72 hours.

  • Antibiotics

It may seem a little counterintuitive, but those antibiotics that you gave your dog for their urinary tract infection can lead to diarrhea. Since antibiotics don’t discriminate between good bugs and bad bugs, they kill off the healthy gut bacteria as well. This diarrhea usually clears up once the antibiotics are finished but can be helped along with probiotics.

Chronic diarrhea is diarrhea that lasts longer than two weeks. The changes in feces can either be intermittent or consistent.  The following are reasons for chronic diarrhea:

  • Chronic Stress

Just as a sudden change in your pup’s lifestyle can sprout some sudden diarrhea, anything that stresses your dog long term can cause diarrhea to continue. Sometimes these stressors may not be so evident, like a neighborhood dog that barks constantly while you’re at work. In order to completely rid your dog of this type of chronic diarrhea, you’ll need to find that stressor and then decrease it or cut it out of your dog’s life permanently. If you’re unable to figure out what is causing your dog stress, other medications may take care of the diarrhea.

  • Food Sensitivities Or Allergies

With the vast expansion of grain-free dog foods springing up on the market, you’ve probably heard something about food allergies and sensitivities in dogs. When dogs with food allergies or sensitivities come across a known problem ingredient, their body mounts a response that brings lots of fluids and immune cells to the gut. This can lead to chronic inflammation of the digestive tract causing chronic diarrhea. This diarrhea will normally clear up once the dog is no longer fed the ingredient they are allergic to. Contrary to popular belief, the most common allergens aren’t to grains, but rather proteins. Feeding a novel protein diet, like venison, buffalo, salmon, or a hypoallergenic diet may help clear up diarrhea related to food sensitivities or allergies.

  • Infections

Parasitic infections like Giardia, whipworms, and hookworms can cause chronic diarrhea. Make sure your dog is dewormed regularly. Bacteria and viral infections can also cause chronic diarrhea. These are usually low-grade infections that tend to smolder rather than burst into flames and may take an extended course of treatment.

  • Health Conditions

Inflammatory bowel disease, pancreatitis, pancreatic insufficiency, and cancer are all chronic diseases that have chronic diarrhea as a symptom. This list is in no way comprehensive, so be sure to take your dog to the veterinarian for any chronic diarrhea.

What Can I Do If My Dog Has Diarrhea?

Some forms of diarrhea warrant a trip to the veterinarian, but not every case. Here are some possible treatments for diarrhea, including things that you can do at home.

Home treatments for diarrhea should only be undertaken if your dog is otherwise healthy and the diarrhea is mild. This means no blood, no black tarry appearance, no dehydration, and nothing lasting longer than 48 hours. Here is a list of what you can do at home:

  • Fill Up The Fluids

The main concern with your dog having diarrhea shouldn’t be maintaining the cleanliness of your carpet, but managing dehydration. Diarrhea contains a lot of fluid that your dog usually resorbs and uses in their body. So make sure that there is always plenty of fresh clean water available to them. If your dog isn’t drinking much on their own, you can try to coax them with some low-sodium chicken broth that is slightly watered down or Pedialyte.

  • Blend It Bland

Feeding a bland diet will kind of give your dog’s GI a break while it heals and repairs. Boil some chicken with white rice without any seasonings, and then feed that to your dog for a couple of days until the diarrhea is better. Afterwards, slowly transition them back to their regular dog food.

  • Vomiting And Diarrhea

If your pup has vomiting issues as well, withhold food for 8-12 hours. You can still offer water, but do so in 1/8-1/4 cup amounts every couple of hours. This just gives the stomach a break. After that, offer very small amounts (a couple of tablespoons) of the bland diet every couple of hours as long as the vomiting doesn’t continue.

  • Other Helpful Foods

Probiotics are always a great option as long as your dog is holding down their food. Feeding plain yogurt can help get those healthy gut microbes back on track and most dogs like it, so it’s win-win. Just feed a couple of tablespoons with every meal. Moreover, since canned pumpkin is a great fiber booster, a couple of teaspoons can be given with every meal.

There are times when you need to take your dog to the vet for diarrhea. Some scavenging dogs may present with diarrhea once a week. As long as it clears up within 48 hours and no other symptoms are present, it’s usually no big deal. However, some dogs may only present with diarrhea when it’s a real problem, so let’s determine when a veterinarian needs to come into the mix.

  • Other Symptoms

Anytime your dog has diarrhea and a fever, lethargy, or the diarrhea is bloody or has a black, tarry nature, see your vet.

  • Dehydration

Dehydration is a dangerous side effect of diarrhea. Check your dog’s gums. If their gums are pale, dry, or sticky, see your vet.

  • Duration

If the diarrhea lasts longer than 48 hours even after using the above home remedies, or if it gets worse since you first noticed it, then see your vet.

  • Preexisting Conditions

If your pup suffers from any preexisting conditions, such as diabetes, Cushings, is prone to pancreatitis, etc, a stop at the vet should be first on your list.

  • Owner’s Intuition

You know your dog best and sometimes things just don’t feel right. What may seem like a simple case of diarrhea that is just setting off alarms in the back of your mind should be seen by a vet.

How To Prevent Diarrhea In The Future

No dog parent wants to have to deal with diarrhea or taking a sick dog to the vet, so prevention is key. To look into preventing diarrhea, we need to revisit the causes in first place. For diarrhea associated with garbage gut, or indiscriminate eating, proper supervision can help prevent this type of problem. Keep watch of your dog so that they don’t eat anything other than their dog food. When you’re not at home, make sure they are in a safe enclosure, free from trash, food items, and potentially hazardous items like fertilizers and pesticides. When you’re on a walk, keep your dog on a leash so you always know what is in front of them.

For infectious causes, always make sure your dog is up-to-date on vaccinations and dewormings. Exercise special precaution when you are at the dog park to make sure your dog isn’t eating feces. Moreover, never let them mingle with dogs that you know are ill.

Decrease stress by making any lifestyle changes as gradual as possible, including changes in diet. Consider giving probiotics when you know that something’s coming up that might cause diarrhea.

Have your pup checked out by a veterinarian on an annual or biannual basis. Report any suspicious behavior or symptoms and discuss normal aging to best keep on top of diarrhea from other health conditions.


Diarrhea in our best friend is a stinky situation at best. The better prepared you are at identifying the cause and preventing dehydration, the better off your pup will be. Remember, if your dog’s diarrhea has other symptoms present and last longer than a couple of days, then don’t hesitate to contact your veterinarian. Furthermore, anything that doesn’t seem normal to you should be a cause for concern.

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