The Common Causes of Diarrhea in Dogs

Dog Diarrhea

Almost 50% of all households in the US own a dog. Mild bouts of dog diarrhea are a common occurrence, and many pet owners are familiar with the presenting symptoms of this, such as loose and sometimes watery stools.

This is something that needs to be monitored closely as there can be other serious reasons for diarrhea. If diarrhea persists, then a vet should be consulted for further treatment.

It is advisable to contact a vet immediately if you have a very young or very old dog with sudden-onset symptoms of diarrhea for assistance, as some infections can be contagious and even life-threatening. 

Keep reading to find out more about the common causes of dog diarrhea and what you can do to help.

Symptoms of Diarrhea

There are a few symptoms of diarrhea in dogs that you need to be aware of:

  • Mushy or watery stool
  • More mucus than normal in stool
  • Asking to go outside more than normal
  • Straining during the process 

If your dog has sunken eyes and a dry nose and gums, chances are they aren’t drinking enough water and have become dehydrated. If your dog is presenting with these symptoms with diarrhea seeing  a vet immediately is highly recommended:

  • Excessive drooling
  • Lack of appetite
  • Vomiting
  • Blood in the stools

Change in Diet or Treats

One of the main reasons for diarrhea in pets is a change in their diet.

It is best to introduce a new diet and any new treats slowly. Start by adding the new food to their current food. Slowly decrease the original food while increasing the new food over a few days.  

This will allow your dog time to adjust physically to the changes in his diet. You’ll also be able to notice any issues that the new food may cause early on. If you suspect the food is still causing diarrhea even though you introduced it slowly, you might need to contact your vet.

Food Intolerance or Allergies

Just like humans, dogs may have intolerances to certain ingredients in their food. This can include dairy products, wheat gluten, and proteins from dairy, beef, or chicken. Each time your pet eats food containing a substance that he is intolerant of or allergic to, symptoms such as diarrhea can occur.

An easy way to test this is using an elimination diet. Start by eliminating everything you think may be an issue. Slowly reintroduce these ingredients one at a time, taking note of any changes in your dog’s behavior and bowel movements.

While reintroducing food, you need to give your dog enough time between ingredients so that they can fully digest the ingredients. If you rush this process, you might not be able to identify all the problem ingredients. Once you know exactly which ingredients have been causing issues, you can find dog food that won’t cause any issues in the future. If your dog has Food Intolerance: consult your veterinarian so that they can help you choose the appropriate food. 

Ingestion of Inappropriate Substances

Dogs are known for their curious nature, and they may eat items that are indigestible or toxic, such as toys, socks, string, chemicals, or certain medications. This can irritate the digestive system leading to diarrhea.

If you think your dog has eaten something they shouldn’t, it’s always a good idea to take them to the vet. If it’s something that will pass, you’ll have some peace of mind, but if it’s a more dangerous substance, the vet will be able to prescribe the appropriate medication or treatment to help. 

Stress or Anxiety

When a dog’s circumstances change, such as moving, adding a new pet to the family, or even construction outside of your home, etc., the stress they experience can manifest in diarrhea. Allow them time to adjust to their new environment and provide them with a space where they can retreat to. 

If stress is the main cause of their diarrhea and it doesn’t clear up with time, you need to consider how you can safely reduce their stress levels. 

Eating Garbage or Spoiled Foods

Dogs, especially puppies, explore things by licking, chewing, or eating them. They will eat rubbish that can contain spoiled food, plants, or even dirt if they have access to it. This can cause an upset stomach or even an intestinal blockage.

Most of these cases have mild symptoms, but it depends on what your dog ate and can lead to serious health risks.

Medications or Poisonous Substances

Some medications, like antibiotics, can disrupt the balance of the intestinal flora and lead to diarrhea. Digestion of certain toxins or chemicals can have similar effects. This is one of the reasons you need to keep these items out of reach of children and animals.

Some Types of Human Food

Avoid food and treats with high levels of salt and sugar. Most dogs are not able to digest large amounts of fat. Avoid feeding your pet human food unless directed by your veterinarian. Dogs do not handle human food as well as we do, and can certain foods may contain additives that can cause harm to your pet. 

Items to avoid: 

  • Grapes, 
  • Raisins, 
  • Onions, 
  • Chocolate and 
  • Items containing xylitol

Avoiding items that contain xylitol as dogs can’t digest it, and it can cause issues. A lot of human food uses xylitol or sweeteners to sweeten the food without adding sugar, so simply picking something that says it’s sugar-free isn’t good enough.

If you want to include these foods in your dog’s diet, stick to safe vegetables and fruits like carrots, green beans, and pumpkin.


Intestinal parasites like roundworms, hookworms, whipworms, or giardia can infest a dog’s gastrointestinal tract, leading to diarrhea. Worms can be ingested when your dog licks his paws after being outside. Deworming is important to keep your dog healthy.

Viral or Bacterial infections 

Dogs are susceptible to bacterial or viral infections, such as Parvovirus, coronavirus, and distemper. Parvovirus and coronavirus spread through feces and are highly contagious.

If not treated, these viruses can lead to serious sickness and death. There are vaccinations available against many canine viruses, so keep this updated. 


Pancreatitis, also called ‘Garbage Gut,’ is inflammation of the pancreas that can affect the liver and lead to diarrhea. The dog’s stool might have a greasy look and can be hard to clean up. Some dogs are more prone to this, and feeding human food is a very common cause of pancreatitis.

Certain dog breeds, such as cocker spaniels, miniature poodles, and schnauzers, are known to have a high occurrence of pancreatitis. 

If this condition is suspected, it is advisable to visit the vet immediately as severe cases of pancreatitis can lead to organ failure and, ultimately death of your pet. 

Inflammatory Bowel Disease (IBD)

IBD is inflammation of the gastrointestinal tract. Dogs with a history of IBD present with recurring diarrhea, vomiting, and weight loss.

Treating Dog Diarrhea

In healthy adult dogs, it may be recommended to withhold food for 12-24 hours or start a bland diet (see below). It is always important to make sure your pet stays hydrated. If they do not want to drink as much as normal, sometimes adding ice cubes to their bowl or giving them ice chips will help.

After a fast, slowly introduce bland food such as plain white rice, boiled chicken, boiled hamburger,  boiled potatoes without the skin, pumpkin, or plain yogurt if your dog can tolerate dairy products.

There are also specialized products on the market that can aid dogs with sensitive stomachs that are prone to diarrhea. Your veterinarian may recommend or prescribe anti-diarrheal medications, special food, and/or probiotics to aid in your pet’s recovery.

You should take your dog to the vet if:

  • Diarrhea continues for more than 48 hours, even if your dog does not seem to be sick
  • Symptoms such as lethargy, no appetite, and continuous vomiting
  • The amount of blood in the stool is larger than a few drops, and it does not clear up 

The Common Causes of Dog Diarrhea

It can be incredibly difficult when it comes to dealing with a sick dog. Since you can’t ask them what’s wrong but can see they’re in pain, it’s important to know the common causes of dog diarrhea. Sometimes it’s simply that they ate something wrong, but if they are incredibly sick, you must take them to see a vet as soon as possible.

The All Animal Vet Clinic is here to help guide you through the journey of owning a new puppy.

Contact us to schedule an appointment in our Lebanon, Indiana Clinic.