It is not nice to experience diarrhoea in your canine friend and there can be many causes of diarrhoea in your dog. As their owners, you will understandably want the diarrhoea to stop as quickly as possible! Oral supplements including probiotics can help in these cases and this article will discuss what they are and how they work in supporting diarrhoea patients.

What causes diarrhoea in dogs?

There are many causes of diarrhoea in dogs, ranging from very minor causes to very severe causes. Below are some of the more common causes of diarrhoea in dogs (this list is not exhaustive):

Dietary indiscretion

Dogs (especially puppies) are well known for scavenging and eating things that they shouldn’t e.g. human food scraps. Sometimes eating certain foods that they are not normally used to can upset their digestive system, usually resulting in acute, short-term diarrhoea.

Allergies/intolerances and inflammatory bowel disease (IBD) 

Dogs with food allergies or intolerances can often develop diarrhoea. In these cases, the diarrhoea commonly occurs quite soon after ingestion of food and signs can be quite acute. In inflammatory bowel disease, it tends to be chronic, ongoing and often low-grade diarrhoea, along with other signs, although acute episodes are also seen.


Pancreatitis is ‘inflammation of the pancreas’ and one of the clinical signs can be diarrhoea, usually along with vomiting and abdominal pain. Often this condition occurs following ingestion of a very fatty meal.


Dogs are prone to picking up infections and ‘bugs’ from other dogs or their environment. These infections may be bacterial, viral, fungal etc. Depending on the infectious agent, it may spread quickly between animals, sometimes affecting multiple dogs in the same household for example (similarly to norovirus outbreaks in humans!)


A common cause of diarrhoea, especially in younger dogs, is parasite infection with species including Giardia and Tritrichomas. These parasites can be the underlying cause in dogs with chronic or acute diarrhoea, and diagnosis is made via lab faecal analysis. Beware that certain parasites (such as the protozoan parasite giardia) are zoonotic, meaning that they can be spread from dogs to humans and vice versa. Therefore, it goes without saying that in ANY diarrhoea case in your pet, it is advised that strict hygiene protocols should be followed.


Gastroenteritis means inflammation of the stomach and small intestine, whereas colitis means the inflammation of the colon. Both of these conditions can lead to diarrhoea in your dog.

In all of the above conditions, your vet may recommend a diarrhoea supplement for your dog. But why, you may ask?

What are diarrhoea supplements?

There are many supplements now on the market for diarrhoea patients and these products expand beyond the small animal field over to horses, poultry and more! Often these supplements come in a powder or a paste form for you to easily administer to your pet and, from experience, most dogs tolerate these really well.

These supplements, which are used with a view to improve your dog’s gastrointestinal function, can be categorised into 3 groups: probiotics, prebiotics and synbiotics.  

Probiotics are live microorganisms 

They are administered and delivered in a specific amount. These live microorganisms are isolated from gut commensals (normal gut bacteria, occasionally called “good bacteria”) or fermented foods. Their overall aim is to maintain gut health by promoting and adjusting the population of favourable gastrointestinal tract microflora.

Prebiotics basically provide the food for bacteria

They contain non-digestible (to mammals!) food ingredients that selectively aid the growth of specific gut microorganisms.

Synbiotics are a combination of both of the above, pro- and pre- biotics

Using a combination of the two can be beneficial because the prebiotic will ensure there is an optimum environment and food source which allows the probiotic to flourish and work as effectively as possible.

How do they work?

The gastrointestinal tract encloses an extremely complex ecosystem and the way that it works is absolutely fascinating to say the least! Most pathogens and bugs enter the gastrointestinal tract via ingestion in the mouth. As a result of this, the gastrointestinal tract needs to have an extremely good defence barrier to cope with these pathogens to protect the body from harm. In order to support the gastrointestinal tract, especially when it is challenged by disease and certain conditions, supplements are often used and recommended for this reason. 

Some studies have shown that with the intervention of probiotics the gut bacterial population can be altered. One study revealed that by introducing a probiotic supplement, the abundance of ‘good’ microbes such as lactobacillus increased and the growth of ‘bad’ microbes such as clostridium were suppressed. It is important to understand that in many disease processes where the patient has diarrhoea, the use of a diarrhoea supplement acts only as therapeutic management, meaning that there are often other treatments and medications required to cure or manage the underlying condition. The diarrhoea supplement aims to treat and manage the clinical signs of diarrhoea. Depending on the scenario, supplements can be used both short and long-term as required.


In answer to the question, ‘how good are supplements for diarrhoea in dogs?’ I would say ‘pretty good’ and I (and many others) feel they provide support to diarrhoea patients. Additionally, scientific evidence is still lacking in this area but there are lots of emerging interest and research within the field of probiotics. I regularly dispense veterinary probiotics to canine patients as a symptomatic treatment for diarrhoea, especially in patients that are otherwise well and anecdotally, I often see a good response and a quicker resolution to normal gut function.

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