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Dogs have some similar gut bacteria to humans.

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How intestinal microbiota help a dog's immune system

By Dr Hester Mulhall MA, VetMB, MRCVS Veterinarian

Updated on the

It's normal for a dog to have intestinal microbiota, but what exactly do they do?

Gut microbiota are the microorganisms (such as bacteria) that live on the inside surface of the intestines, particularly in the colon. It is normal and healthy for there to be intestinal microbiota in dogs, just like with people. The microorganisms that live in the gut have co-evolved along with their canine hosts over thousands of years and, as long as the delicate balance is maintained, it is a mutual relationship that benefits your pet’s health.

What exactly do microorganisms do in a dog's gut?

One of the roles of the layer of microorganisms within the gut is to help support the dog’s immune system. It achieves this through a range of different processes, many of which we are still learning about.

One of the ways it supports the immune system is by preventing harmful disease organisms from colonising the gut wall. But there are many other useful ways that these microorganisms may be helping out – ranging from producing natural antibiotics to stimulating cells involved in the body’s natural immunity. Some gut bacteria also help to digest food and can be involved in the availability of vitamins.

Do dogs have the same gut bacteria as humans?

Dogs have some similar gut bacteria to humans, but will have different types as well. In fact, the gut biome is unique to each individual – and it will even vary between two dogs.

What are probiotics?

Probiotic products contain live microorganisms and are sometimes fed to pets with the aim of improving gut health, particularly in the large intestine. The idea is that they will compete with disease-causing bacteria to prevent their growth and will produce short chain fatty acids (SCFAs) beneficial to gut health. It is also thought that feeding live bacteria can alter gut pH, which helps to support the dog’s own ‘good bacteria’.  

There are a lot of probiotic products available and some of these have better research behind their efficacy. Most veterinary probiotics contain a bacteria called Enterococcus faecium, but the strain that is used varies and some of these are thought to be more effective than others. You can speak to a vet to see what product they recommend, based on the science available.

Probiotics should be differentiated from prebiotics, as the two are sometimes confused. A prebiotic refers to a type of fibre that is fermented by the gastrointestinal microbiota to produce SCFAs. These help to nourish the cells that line the intestinal walls, benefitting gut and overall health.

Are probiotics good for dogs?

If your pet is otherwise healthy, then a probiotic is probably unnecessary. Yet some people do feed their pet a daily probiotic supplement and this will not usually cause a problem. A vet may prescribe a probiotic to help restore healthy gut microorganisms, if your pet has been unwell or treated with antibiotics. Some research has shown benefits in the use of probiotics in this way.

What can I give my dog for a healthy digestive tract?

A high-quality complete dog food should contain everything needed to help keep your dog’s digestive tract healthy. If they are experiencing symptoms such as diarrhoea or vomiting on a regular basis, then this may suggest an underlying problem. Having said that, these signs are very non-specific and can indicate a number of issues. Seeking veterinary advice will ensure that these are investigated in the appropriate order, and suitable tests or treatments can be offered.

How can I boost my dog's immune system?

One of the most effective ways to boost your dog’s immune system is through keeping up-to-date with vaccinations. A vaccination stimulates their immune system through triggering a series of natural processes within the body. This includes developing immune cells and antibodies that help to provide protection against diseases. There is some research to show that probiotics may help to support a healthy immune system, but this should not replace vaccinations.

Are pets the new probiotic?

This question refers to the theory that pets will be increasing the variety of microorganisms that you find within your home. Given that humans can pick these up from their environment, it means that people with pets are likely to be exposed to a greater range of microorganisms than those without pets. There is some evidence that this can be beneficial to human health, for example by reducing the occurrence of allergies. But pets can also carry disease-causing organisms that are zoonotic (can be spread to people) and so the advice is to always wash your hands after handling a pet, especially before eating.

How should I talk about microbiota with a vet?

You can make an appointment with a vet to discuss your pet’s digestive health. If your pet is experiencing any symptoms, then it can be helpful to keep a note of when these occur, along with a food diary that details everything your pet is fed (including treats). The vet will be able to discuss any concerns or questions you might have about your pet’s health, and to also suggest any necessary diagnostic tests or dietary trials.

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