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Common Causes of Diarrhoea in Dogs

Diarrhoea is a common problem in canines. It can be acute or chronic and may be caused by a variety of different things.

If your dog has diarrhoea, you might notice that they’re asking for more trips outside. They could be standing by the back door more often so that they can relieve their bowels.

When your dog does have a bowel movement, its stool will be loose and watery. This may last for a few days or several weeks.

Short-term diarrhoea indicates an upset stomach, likely due to something that your dog has eaten. However, ongoing diarrhoea can be a cause for concern and can indicate an underlying health problem.

If your dog has had diarrhoea for more than a week, it’s worth taking them to the vets to get checked so that they can identify any potential problems that might be causing the issue. The vet may also recommend a diet with specialised dog food for diarrhoea that will help to tackle the issue and keep your dog healthy until they recover.

Signs and Symptoms of Diarrhoea in Dogs

Some of the key symptoms of diarrhoea in dogs include:

  • Loose, watery stools
  • Increased frequency of bowel movements
  • Mucus or blood in the stool
  • Dehydration
  • Weight loss
  • Pale gums
  • Lethargy
  • Muscle weakness
  • Vomiting
  • Lack of appetite

Common Causes of Diarrhoea in Dogs

If your dog has diarrhoea, it may not always be a cause for concern. Diarrhoea can often be caused by something simple like eating spoiled foods or it can indicate a more complex issue.

Here are six of the common causes of diarrhoea in canines.

Eating a Different Diet

If a different brand of dog food was on offer at the store and you decided to buy that instead of the usual brand, it might be the main culprit of diarrhoea. Your dog’s stomach will be used to a certain diet and suddenly switching to another diet can cause upset.

If you are switching to another kind of dog food, make sure to do so gradually. This will allow your dog’s digestive tract time to adjust properly to the new diet.

Eating Contaminated Foods

Contaminated food that contains bacteria and viruses can irritate the lining of your dog’s digestive tract and may lead to diarrhoea. Most of the time, diarrhoea caused by the consumption of contaminated food will disappear after a week.

However, it’s still important to get your dog checked at the veterinarian clinic. Some contaminants can lead to more serious issues for your dog, such as pancreatitis.

Certain bacteria and viruses can enter your dog’s body through spoiled, rotting, or uncooked foods. Common viral diseases include Zoonoses, Parvovirus, rotaviruses, and coronaviruses. 

These viruses may cause ongoing diarrhoea as well as other symptoms, such as vomiting, weight loss, coughing, and fever. They can be life-threatening so it’s essential that your dog receives immediate care. 

Intestinal Parasites

Intestinal parasites can be found in contaminated water or animal faeces. If your dog drinks puddle water or licks faeces that have been left on the road when you take them for a walk, they may ingest parasites.

The ingestion of parasites can cause diarrhoea that has a very wet, foamy appearance. It may contain a lot of mucus and have a noticeable smell.

Your dog may need to take medications to get rid of the parasites. These medications can be supplied by your vet.

Certain Medications

Speaking of medications, if your dog has been prescribed certain drugs by the vet, this may be the cause of your pet’s diarrhoea. 

Common medications that have diarrhoea as a side effect include non-steroidal anti-inflammatory drugs (NSAIDs) and NMFA receptor blockers. The mechanism of action for these drugs disrupts the digestive tract and causes frequent, loose stools.

If you suspect that it’s your dog’s medications that are causing diarrhoea, speak to your vet. They may prescribe alternative medications to treat the problem.

Ingesting Foreign Objects

Dogs have a knack for eating unusual objects. When they ingest something that they aren’t supposed to, it can lead to diarrhoea.

If the objects that they ingest are hard and large, they can become lodged in their digestive tract, causing a lot of issues in their bowels. Not only can these foreign objects cause diarrhoea in your dog, but they may also be life-threatening.

There are other symptoms that can indicate the presence of foreign objects in your dog’s stomach or bowels. Loss of appetite, vomiting and a swollen abdomen can all be tell-tale signs that something has become lodged in your dog’s digestive tract.

It’s very likely that your dog will require surgery to remove the foreign object. The quicker the object is removed, the better the outcome for your dog so it is in your best interest to take them to the vets immediately.


Another fairly common cause of diarrhoea in dogs is toxicities. When your pet eats something that is toxic or poisonous to them, it can cause harm to the digestive tract, leading to diarrhoea and other symptoms.

There is a huge range of different things that are known toxins to dogs. Common toxic substances to dogs include chocolate, bluebells, daffodils, holly, some mushrooms, multivitamin tablets, and silica gel packs that are often used in the packaging of moisture-prone products.

As a dog owner, it’s almost impossible to keep all of these things away from your dog. A lot of the time, you won’t even know that your dog is eating a toxin until it is too late.

Dogs often sniff and lick different flowers and shrubs while they are out on a walk. It’s difficult to know exactly what they are ingesting.

Diarrhoea caused by the ingestion of a toxin may last a couple of weeks and in some cases, it will clear up by itself. However, if your dog’s diarrhoea persists for several weeks, you must take them to see the vet.