Skip to content

Save 20% on your first AutoShip with promo code FAMILY20!Learn More

Common Causes of Diarrhea in Dogs

If you are a pup parent, chances are you’ve dealt with doggy diarrhea at least once. Diarrhea in dogs can be caused by a number of things, ranging from very minor digestive issues to serious illnesses. 

We will discuss the most common causes of diarrhea in canines below, but let’s start with the basics. What is considered diarrhea in dogs?

Diarrhea usually means a loose, unformed, or liquidy stool. It may happen just once, or occur frequently in multiple episodes. It may also be a larger amount than you are used to seeing. This happens when things move through the digestive tract more quickly than usual, resulting in less water absorption (along with reduced nutrient and electrolyte absorption). 

One instance of diarrhea usually isn't a cause for concern, but repeated episodes can be a sign of health issues that require immediate attention. It’s always best to consult your veterinarian for advice if your furry friend experiences diarrhea. 

We’ll break the most common causes of doggy diarrhea into six categories: Food Intolerance, Allergies, and Dietary Changes; Dietary Indiscretion; Parasites; Infection or Illness; and finally, Emotional Upset and Stress. 

Food Intolerance, Allergies, and Dietary Changes

One cause of temporary diarrhea in dogs can be an abrupt change to their diet. If you switch your pet to a new dog food without slowly transitioning, your pup may experience some loose stools. 

To avoid this, gradually switch your pet to their new diet over 5-7 days. Start with a mixture that is 25% new diet and 75% previous diet, then 50%/50%, 75%/25%, and finally 100% the new diet.

Food intolerance and food allergies can also be a cause of canine diarrhea. If your pet is intolerant of an ingredient in the food they eat, they may experience GI upset including diarrhea. Food allergies - where the pet is allergic to a specific protein in one of the ingredients of the food, can cause an immune response, which may include diarrhea as a symptom. 

If your pet is experiencing a food intolerance or allergy, your vet may have you try an elimination diet to identify the offending ingredient. They may also prescribe a hypoallergenic diet, such as Hills Skin/Food Sensitivity z/d Dry Dog Food or Blue Natural HF Hydrolyzed - Food Intolerance Dry Dog Food.

Besides reacting to foods, pets can also react to certain medications. For example, it is not uncommon for dogs taking antibiotics to experience diarrhea. In these cases, a canine probiotic such as VetClassics Protegrity EZ Probiotic & Enzyme Powder for Dogs & Cats can help restore balance to the GI tract.

Dietary Indiscretion

Dietary indiscretion can include your dog woofing down their dinner too quickly, getting into the garbage and munching on some trash or spoiled food, or eating something that irritates their digestive tract in general. Basically, eating something they shouldn’t have. 

Usually, diarrhea caused by dietary indiscretion is temporary and not indicative of a serious problem. However, there are cases where it can become serious. 

If your pup ingests something toxic or poisonous, things can become dire very quickly. Further, if your dog ingests a non-food item, like a toy or a scrap of clothing, it could create an intestinal blockage, which is a very serious issue. 

For these reasons, it is always best to get your canine pal checked out by a veterinarian to rule out anything problematic or life-threatening.


Intestinal parasites are not an uncommon occurrence in dogs and can be a source of diarrhea for your pet. These can include worms like roundworms, whipworms, and hookworms, along with microscopic protozoans like coccidia and giardia. 

It is recommended that dogs have a fecal analysis annually to check for parasites, and it may also be one of the first tests your vet performs if your pup is experiencing diarrhea. 

There are some products available, such as Interceptor Chewables for Dogs, that can actually prevent certain intestinal worms in dogs in addition to treating them. However, your vet is the best place to go for advice on specific deworming agents that would best suit your pet and their circumstances. 

For other parasites like giardia or coccidia, your vet will likely recommend a prescription medication such as Metronidazole or Albon (sulfadimethoxine), respectively. 

Infection or Illness

Sometimes diarrhea can be caused by a viral infection, such as canine parvovirus, canine distemper, or canine coronavirus. 

These viruses are not only highly contagious but can be very dangerous and even deadly - especially parvovirus and distemper. It is extremely important for pets with these suspected illnesses to be seen by their veterinarian immediately.

Bacterial infections, such as salmonella, can also cause diarrhea in dogs.

Besides viral and bacterial infections, there are several other illnesses that can be the culprit. Examples can include colitis, inflammatory bowel disease, irritable bowel syndrome, kidney and liver disease, and cancer.

These issues should be addressed and diagnosed by a veterinarian so a proper course of treatment can be implemented. For example, if a dog is diagnosed with IBS (Irritable Bowel Syndrome), a vet may recommend a medication like Librax to help relieve symptoms. 

Emotional Upset and Stress

Humans aren’t the only species subject to stress and emotional upset. Our furry friends can also experience these unpleasant emotions, and the result can often be acute diarrhea. 

This can be common after major environmental changes, travel, boarding, introduction of a new pet or family member, or even a result of separation anxiety.

For nonspecific diarrhea in dogs, medications like Diawin can be helpful in relieving symptoms. 

You can also talk to your vet about anti-anxiety medications, such as Gabapentin or Fluoxetine, for pets who experience anxiety.

When To Seek Immediate Care

It can be alarming when our canine pals experience diarrhea. Most of the time, the cause is something minor and can be easily treated or may resolve on its own. The main things pet parents want to monitor are how long the diarrhea lasts and if there are any other symptoms. 

If the diarrhea is accompanied by other symptoms, such as vomiting, lethargy, weakness, fever, or pale gums, you’ll want to take a trip to the vet right away. 

Other situations that require immediate medical care can include diarrhea that is very frequent or long-lasting. This can result in dehydration and can also be a sign that something else is wrong. Dogs with certain pre-existing conditions should also be seen by their vet promptly if they begin to experience diarrhea. 

Finally, any time that you feel something isn’t right with your pup it is always a good idea to have them checked out. It is always better to be safe than sorry when it comes to our canine companions. 

Previous article Common Poison Dangers for Pets and How To Avoid Them
Next article Flea and Tick Prevention for Dogs and Cats: Making Sense of All Your Options