The importance of a healthy microbiome for dogs

Dr Jayne Laycock BVetMed MRCVS

You may have heard the term ‘microbiome’ getting thrown around a lot recently – on TV, in award-winning books, and even just in everyday conversation – and there’s good reason for that.

The term ‘microbiome’ refers to the community of bacteria that live inside of us (and other living organisms), in the gut, but also in the mouth and other areas of the body. Recent research from leading scientists like Tim Spector has suggested that a healthy microbiome plays an immense role in promoting overall health, longevity and wellbeing, and warding off more serious health issues.

Of course, our pets have microbiomes too…

What is your pet’s microbiome?

The right way to think of a microbiome (both yours and your pet’s) is as a living ecosystem that exists inside the body. But instead of lush vegetation, voles, badgers, and maybe the occasional wildebeest, this entire ecosystem is made up of a careful balance of microorganisms, including fungi, bacteria and viruses.

The more we learn about the microbiome, the more incredible we find out it is. Increasingly, the microbiome is even being seen as a functioning organ in its own right.

The gut microbiome is perhaps the one that gets the most attention. It’s made up of all the microorganisms living along the gastrointestinal tract, from the mouth to the tail. In dogs, around 98% of the gut microbiome is made up of bacteria.

These good microorganisms live in harmony with your dog’s body, with dog and microbiome supporting each other in various ways.

Here’s just one example: bacteria in the intestine ferment some types of food, producing important nutrients and ‘postbiotics’ for your dog to use. For example, they break down certain types of fibre into short-chain-fatty-acids (SCFAs). These SCFAs are then absorbed by your dog’s colon and used for energy. In this way, the bacteria help your dog by releasing an energy source from fibre, which your dog otherwise wouldn’t have been able to digest and use.

A healthy microbiome may also be one of the keys to a healthy mind, as it’s now known that a large portion of the body’s serotonin is actually made in the intestine. Serotonin is a very important neurotransmitter, meaning it plays a vital role in the nervous system. It’s also known as a ‘happy hormone’ that influences mood.

All in all, there’s good reason to think that a healthy gut microbiome could also be important for controlling anxiety.

So, what’s your dog doing to contribute to this great two-way relationship? Well, other than providing shelter for those friendly microbes, the cells lining your dog’s intestine also feed the bacteria by producing a mucous that they consume. Everybody wins!

Why is a healthy microbiome important?

The microbiome is important because it’s involved in several bodily functions, including:

- Teaching the immune system the difference between ‘normal’ or ‘good’ micro-organisms and infectious agents (such as harmful bacteria and viruses)
- Protecting against infectious agents
- Metabolism, or converting food into energy.

In a healthy microbiome, the vast majority of bacteria are beneficial, with only a very small number being harmful.

As long as the immune system is also healthy, it will ‘tolerate’ these good bacteria – meaning that it won’t react to them. But if the number of harmful bacteria living in the microbiome increases, the immune system will start to attack the microbiome. Importantly, it will also start to attack the tissues that the microbes are living on.

What would this mean for your dog? Well, let’s take the mouth for example. In your dog’s mouth, an unbalanced or unhealthy microbiome can cause the immune system to attack various tissues, including the gums and the ligaments that hold your dog’s teeth in place.

This can lead to:

- Gingivitis (inflamed, swollen gums)
- Stomatitis (generalised inflammation in the mouth)
- Periodontitis (damage to the ligaments which hold the teeth in place), which affects around 70% of all dogs!
- Tooth loss

Put simply, an unhealthy oral microbiome contributes to progressively worsening dental issues.

You might be surprised to learn that the microbiome also affects many other organs, as well the gut. Changes in the microbiome have been linked with a large number of health concerns, such as:

- Gut issues
- Kidney issues
- Problems with the nervous system
- Diabetes
- Heart problems
- Obesity
- Allergies

While more research is needed into how an unhealthy microbiome may contribute to causing these issues in dogs, or how these issues might negatively alter the microbiome, it’s clear that the microbiome is an important part of your dog’s body!

Signs of a poor microbiome in dogs

There’s no clear-cut, one-size-fits-all list of symptoms of an imbalanced microbiome. That’s because an imbalanced microbiome is thought to have a vast range of potential knock-on effects.

In your dog’s mouth, an imbalanced microbiome may contribute to:

- Bad breath
- Red, swollen gums which may bleed easily
- Red, swollen lips, inner cheeks, tongue, or fauces (back of the mouth)
- Tooth loss

If you’re worried that your dog has any of the above, you should call your vet as soon as possible.

A chronic imbalance in the gut microbiome can lead to a condition called ‘leaky gut syndrome’. This is a condition where the gut’s defence system is damaged, and substances that normally can’t pass through the gut wall are now able to get through and enter the blood stream. Some signs of leaky gut syndrome include:

- Diarrhoea or soft stools
- Excessive gas
- Weight loss
- Sickness

Leaky gut syndrome can also have more serious effects, leading to generalised inflammation in the body. Since the body’s immune system doesn’t recognise the new substances in the blood stream, it reacts to them as if they were harmful.

How can I improve my dog’s microbiome?

Your dog’s microbiome will be affected by many things, such as age, genetics and diet. Currently, there’s lots of ongoing research into how diet can alter the microbiome, and which diets are best for a healthy microbiome. The aim of a microbiome-friendly diet is to support naturally good bacteria while dislodging bad bacteria, in order to restore an optimal balance.

Final thoughts

More research is needed, and plenty is already underway, into the role of the microbiome and how to use diet to change it for the better. However, enough research does already exist to show that the microbiome is important for overall health, and not just for gut health. In the mouth, an unhealthy microbiome can lead to dental issues, which will worsen with time. So, if your dog has red gums or unexplained smelly breath, have a chat with your vet!

Want to learn more about canine dental care? Maybe you’ve been chomping at the bit to find the answer to a burning question? If so, check out our Ask the Vet: Dental Care blog post with Dr Jayne Laycock BVetMed MRCVS.