Weaning is a stressful time for puppies. Being separated from their mother, brothers and sisters, as well as settling into a new family and getting used to new food rather than milk, there are a lot of big changes happening at the same time. All this whilst being in a phase of huge growth, development, and learning. We know that the brain is directly linked to the gut via the gut-brain-axis and that stress can negatively impact digestion, but diarrhoea and upset digestion is a common occurrence in puppies and young dogs. This can be partly accounted for through adjusting to new or changing diets and partly through the stresses on puppies. But what affects a puppy’s digestion, microbiome health and how does this link to their digestive and immune health?

Why is a puppy’s microbiome development important?

A puppy’s growth period before they reach adulthood is a crucial period where their digestive tract is colonised by microorganisms to develop their microbiome. During this period the microbiome is particularly sensitive to disruption, which may cause dysbiosis (an imbalance of the microbiota) and knock on digestive upset. Dysbiosis in puppies has several effects on health. These effects include intestinal permeability, meaning that the gut is not acting as a barrier to potential toxins and other things in the gut, but allowing them to pass into the bloodstream and the body. Dysbiosis can also mean inflammation and a reduction in the anti-inflammatory factors produced by the body as well as competition for nutrients between the gut microorganisms, and acute diarrhoea. This disruption of the microbiome during puppyhood can impact dog health in adulthood. During the vulnerable stage of weaning and growth in puppies, diarrhoea affects approximately one quarter of puppies! Despite this being such a common occurrence there is very limited data into the puppy microbiota and how this relates to digestive health. There is growing evidence that the microbiota influences a puppy’s health and immunity throughout their life.

From the age of two days old the microbiome is developing, increasing in richness, as the digestive system also develops, increasing its ability to absorb nutrients, produce bile acids and develop immunity. From one to twelve years old no differences were seen in microbiome populations, indicating that populating a healthy microbiome during the first year of life is important.

What affects a puppy’s microbiome population?

Cohabitation with humans can lead to shared bacteria forming within the microbiome. A study in adult dogs found that a close relationship between dog and owner lead to microbial exchanges and shared bacteria within the microbiome, than for dogs and humans with a more distant relationship. As the microbiome of puppies is more sensitive to changes than that of adult dogs it follows that the same is hypothesised to be true in puppies and that this transfer can occur regardless of age.

Environment shapes the microbiome of puppies. City-dwelling puppies are found to have a higher species diversity within their microbiome than rural puppies. This is thought to be due to the variety of environments to which they are exposed, such as parks, streets, etc and the number of other dogs and people met.

Dietary impacts upon the microbiome of puppies have not been studied as it has in adult dogs, however many findings are considered transferable. As puppies’ microbiome is developing and sensitive to influences it also follows that these changes in a puppy’s microbiome population could be long lasting, rather than transient as they are in adult dogs, the microbiome returning to its default when the dietary changes are reversed. These effects on the microbiome population include how dietary changes such as increased fibre leading to increased abundance of particular bacteria species, as well as changes seen for a high meat or raw diet.

The microbiome and immunity

The microbiome is a first defence when it comes to immunity. The mother’s colostrum and milk hugely impact the microbiome and its potential to combat potential pathogens. Puppies with a deficiency of colostrum or milk intake have a greater risk from infectious diseases. In these cases, however, there are alternatives which can be used. Canine colostrum banks and canine serum or plasma supplementation showed beneficial effects upon puppies’ health, growth, and digestive as well as general health. Hyperimmune egg powder supplementation also conveyed benefits of increased growth of newborn puppies and a lessened risk of canine parvovirus infection.

Probiotics can be supplemented to provide support to the immune system, and have shown to stimulate growth also. More studies in puppies are required to understand all of the ways that probiotics effect the microbiome and more general health.

Firming stools

I’ve mentioned already that diarrhoea affects approximately 25% of puppies during this growth period, so how can we avoid this? Firstly, there are many factors which affect digestion, and cases of acute diarrhoea in puppies should be discussed with your veterinarian. Building the health and diversity of the microbiome and wider gut health is beneficial. Due to the direct links which we now know are present between the gut and many other areas of the body, good gut health has benefits to general health. An example of this is the gut-brain-axis. Building microbiome health supports brain health, stress reduction and focus. Digestive upset initiating in stress may be improved through this effect too, helping to end the cyclical nature of stress causing upset digestion.

Supporting digestive health in puppies is an important consideration. As studies found that the first year of life is where the microbiome is receptive to long term changes (rather than short term effects seen in adulthood). Although more research is required in this area it appears that the state of the microbiome during puppyhood sets the tone for adulthood and that a diverse microbiome is hypothesised to be connected with best health in adulthood.

Summary

There are so many factors which impact a puppy’s microbiome, from the type of birth and maternal factors to their environment. Their microbiomes change with age, their diet and the environment and close proximity to other dogs and humans. Antibiotics reduce microbiome diversity, and vaccinations are recommended for puppies as a measure to protect against disease which can cause dysbiosis and illness in vulnerable young puppies. Supporting a puppy’s digestive health is important for their long term health and wellbeing.

References

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