An introduction to the canine microbiome

Did you know that your dog is basically made of microscopic critters? Ok, that’s not exactly true, but scientists estimate that the average dog has around the same number of microbial cells as it does cells in its entire body – and most of these are concentrated in their digestive systems, where they play an essential role in the digestion of food, and also contribute to a wide range of other important bodily functions.

The community of these organisms that live within the digestive tract, or gut, are known as the gut microbiome, and there are literally trillions of them. Most of the bacteria in the gut are completely harmless, with many being classified as ‘good’ bacteria which are involved in aiding digestion, boosting immune system health, or supporting brain health. There are less welcome bugs in the mix as well, with many species of ‘bad’ or disease-causing/pathogenic bacteria usually present, but if these are balanced out with ‘good’ bacteria then they don’t usually cause active disease. There are also bacteria that are known as opportunistic pathogens – this means that most of the time they are harmless, but if given the opportunity, they can become pathogenic. This means that your dog’s body is performing a continuous balancing act within the gut biome to ensure that the ‘bad’ bacteria don’t start to dominate and overwhelm the ‘good’ ones. 

The gut microbiome is involved in lots of essential processes for health, including helping to digest food, manufacturing vitamins (like vitamins B12 & K), transforming indigestible fibre into short chain fatty acids, and many more. Some of the compounds the bacteria produce are essential for health but cannot be produced by the body itself, so dogs (and ourselves) depend upon the ‘good’ bacteria to produce them. In addition, the canine microbiome has an essential role in the dog’s immune system and overall health; it can educate the immune system, protect against pathogens, and through these, and its metabolic actions, it directly or indirectly affects most physiological functions.

There are lots of factors that can influence the health of your dog’s microbiome, from their diet and lifestyle to their age and social lives – but the biggest impact often comes from diseases, particularly those affecting the digestive system, such as gastroenteritis, which can lead to inflammation of the gut wall. Digestive disorders can lead to changes in the balance of bacteria in the gut, known as dysbiosis, which can then lead to secondary health problems linked to the products that the gut microbes produce. And it’s not just the disorders themselves that can cause problems – the treatments that vets and doctors often prescribe, such as antibiotics, can also have negative effects on the microbiome, leading to a vicious circle of ever worsening gut diseases such as colitis, inflammatory bowel disease and ulcerative colitis. On the other hand, a stable, balanced microbiome, undisturbed by antibiotics, can help prevent excessive inflammation and also help the immune system to respond appropriately to infections.

A lot is still not fully understood about the microbiome, and we are learning new things about it all the time. For example, we are starting to appreciate how important the preparation of a dog’s diet is to the health of their gut microbes, with significant differences in the microbiome make-up of dogs fed dry foods versus those fed fresh cooked or raw diets.

Despite all the unknown unknowns surrounding canine microbiome science, it is clear that the microbes in our dog’s tummies hold many of the keys to health and wellbeing, and by analysing them, we can potentially transform the future of pet healthcare.