Discover 5 amazing facts about the canine gut microbiome- the trillions of bacteria influencing your dog's immune, metabolic and intestinal health.
- Gut microbes play a key role in canine health
- Diet shapes the dog microbiome
- The dog microbiome closely resembles the human one
- A dog's temperament may be linked to their gut bacteria
- Dogs share similar skin microbes to their owners
- Article Summary
1.) Gut microbes play a key role in canine health
It is increasingly clear that the microbiome plays a vital role in the health of mammalian hosts- including dogs.
Like ourselves, dogs exist symbiotically with the community of microbes on and in their body.
In return for space and nutrients in the canine gut, the microbiome acts as an "organ" in your dog's body, performing numerous vital health functions, including:
- Protect against pathogenic microbes by taking up space and food
- Train the immune system to discriminate between harmless bacteria and harmful invaders
- Synthesise key vitamins
- Produce metabolites that nourish gut health, called postbiotics
A range of health conditions- intestinal and otherwise- are accompanied by shifts in the canine microbiome, suggesting a link.
For example, the dog microbiome is significantly altered in canines suffering from acute and chronic diarrhoea.
Furthermore, these shifts in microbiome composition are broadly consistent across affected dogs.
Butyrate is the primary fuel source for cells in the dog's gut lining, an important barrier that helps regulate the immune response.
Low levels of this important compound can compromise the gut wall and trigger chronic inflammation.
2.) The dog microbiome is shaped by long-term diet
Macronutrients are the nutrients needed in large amounts for an animal to thrive, including:
- Carbohydrates
- Proteins
- Fats
The macronutrient content of a canine's diet plays an important role in shaping which bacteria colonise their gut and in what proportions.
Several studies have explored the impact of a raw-feeding diet (high in protein and fats whilst low in carbohydrates) vs a kibble-based diet (high in fibre and carbohydrates whilst low in protein and fats).
In short, a kibble diet is linked to an increase in bacteria from the Firmicutes species, a classification that includes most butyrate-producing bacteria.
Conversely, the raw meat diet- high in fat and protein- has been shown to enrich the canine microbiome in Proteobacteria and Fusobacteriota bacteria.
Whilst a predominately meat-based diet is linked to reduced diversity and inflammation in omnivorous humans, there is evidence to suggest that the carnivore microbiome is better specialised to thrive on a protein diet.
For example, Fusobacterium varium is known to produce butyrate from protein sources.
Interestingly, a small study found that dogs fed a raw, meat-based diet for a year saw an enrichment in this species. Likewise, Fusobacterium varium is seen in higher proportions among carnivores such as cats and wolves.
These findings suggest that dogs and other carnivores may have microbiomes able to source butyrate from protein- something the human gut can only make through fibre fermentation.
A raw diet high in animal protein is also observed to boost bacterial species from the Clostridicae family.
Many clostridium species have been linked to inflammation and gastrointestinal disease, most notably clostridium difficile and clostridium perfringens.
Nonetheless, we cannot simply assume that all Clostridium species impact dogs the same way as humans. For a start, the Clostridicae family embodies 15 genera- each containing thousands of species.
It has been suggested that bacteria from the Clostridicae species (such as clostridium) are not detrimental to health but actually aid dogs in digesting protein.
A raw, meat-based diet has also been linked with better faecal health scores in dogs- meaning firmer stools.
Whilst dogs may be better equipped to handle a high protein diet, research shows that plant-based fibre can encourage the growth of beneficial microbes and boost postbiotics in the canine gut.
For example, fibre supplementation with beet pulp has been shown to increase the abundance of fibre-degrading bacteria and boost the production of short-chain fatty acids, including butyrate.
Based on the current evidence, the ideal canine diet will contain plenty of plant-based vegetable fibre in combination with high-quality protein.
If you choose to raw feed your pooch, opt for human-grade meat and practice good food hygiene to minimise the risk of food-borne bacterial infections.
3.) The dog microbiome closely resembles the human one
Humans and dogs share many similarities owing to their parallel evolution, such as the ability to read facial expressions and empathise with others.
As it turns out, our canine companions might also resemble us in another exciting way.
A study published in the journal Microbiome sought to measure the similarity between the dog and human microbiome.
The study found that a dog microbiome bears more similarities to the human microbiome than either mice or pigs- animals commonly used to predict how something will influence gut microbiota in humans.
Much like a human biome, the dog microbiome is primarily composed of five bacterial species, including:
- Firmicutes
- Bacteroidetes
- Fusobacteria
- Proteobacteria
- Actinobacteria
Whilst the dog microbiome shares numerous species with the human microbiome, they differ at the strain level.
A healthy dog microbiome also contains higher proportions of Fusobacteriota relative to humans.
Nonetheless, the study strongly suggests that a dog microbiome is a better research model for humans than the two most popular animals currently- pigs and mice.
4.) A dog's temperament may be linked to their gut bacteria
In a much-cited study, researchers were able to make a timid mouse bold and vice versa by transplanting them with each other's gut microbes.
The implication is that animal behavioural traits- including anxiousness and boldness- are somehow shaped by the gut bacterial community.
Interestingly, several studies have identified a link between a dog's microbiome makeup and behavioural traits like sociability and aggressiveness.
Whilst these studies fail to demonstrate causation, they hint at a potential role for the microbiome in shaping a dog's temperament.
For example, one study sequenced faecal samples from 42 dogs split into three groups- phobic, aggressive and "normal".
Upon analysis, the researchers found that a "peculiar gut microbiome structure" accompanied aggressive behaviour in canines.
More specifically, the aggressive dogs exhibited high biodiversity and enrichment in sub-dominant species. Conversely, anxiousness was associated with an enrichment of Lactobacillus- unexpected considering its beneficial properties.
A study published in the journal Nature earlier this year also found a statistically significant correlation between a dog's microbiome composition and certain behavioural traits.
Moreover, the researchers could predict behavioural traits such as motivation and sociability with moderate accuracy based on a dog's microbial profile.
A study on rescue dogs also found unique microbial patterns linked to aggressiveness. Interestingly, some of the species identified were also tied to gastrointestinal diseases.
All of these studies fall short of proving causation, but they certainly warrant further investigation.
If it turns out that a dog's behavioural traits are shaped by microbiome composition, then it opens the possibility of tailoring their temperament via microbiota-targeted treatments.
Currently, that's purely hypothetical, and the jury is out pending further studies.
5.) Dogs share similar skin microbes to their owners
It is often said that owners look like their dogs, and that's precisely the case when it comes to the skin microbiome.
According to multiple studies, dogs are more likely to have similar oral, faecal, and skin microbes to their owners than other people, with skin microbes boasting the greatest similarity.
Evidence suggests that this microbial exchange benefits humans, particularly in early life; children raised in a pet-owning household experience lower levels of allergies than children raised in pet-free households.
Researchers theorise that exposure to animal microbes improves your immune education, which is conducted by your gut microbiome during infancy.
Article summary
-
Dogs are colonised by trillions of microbes living on and in their bodies. The largest community of microbes can be found in the large intestine, predominately made up of bacteria.
-
A dog's microbiome composition is shaped by its long-term diet and certain medications, particularly antibiotics.
-
The community of bacteria in a dog's gut plays a crucial role in canine health, influencing their metabolic, immune and intestinal health.
-
Many disease states are accompanied by disruptions to the canine gut microbiome, which researchers call dysbiosis.
-
The dog microbiome contains many of the same bacterial species as the human microbiome but differs at the strain level.
-
Emerging research has found correlations between a dog's microbiome composition and behavioural traits such as aggression and sociability. Whilst compelling, they fall short of proving causation.
-
A kibble-based diet is linked to increased fibre-degrading bacteria and higher butyrate levels. Conversely, a raw, meat-based diet is associated with enrichment in Proteobacteria and Fusobacteriota species.
-
There is evidence to suggest that the dog microbiome is better equipped to handle a high-protein diet, with the ability to make butyrate from protein sources.
-
Feeding your dog a diet rich in indigestible plant-based fibre can help cultivate beneficial bacteria and increase butyrate levels. If you choose to raw feed, opt for human-grade meat and practice proper food hygiene.
☝️DISCLAIMER☝This article is for informational purposes only. It is not intended to constitute or be a substitute for professional medical advice, diagnosis, or treatment.
