This section continues the discussion I began in The Highly Sensitive Dog, 2nd edition.

As I just knew was going to happen as soon as I published the book, I came across a paper  in the veterinary literature that I would have included had I known about it earlier. This article is about that study.

Importance of diet

Who lives there — i.e., the composition of the gut's microbial community — is largely a function of what there is to eat. In other words, it largely depends on the dog's diet.

And yet diet is seldom considered, and never considered in any depth, in these studies of the canine gut microbiota.

Who lives there is largely a function of what there is to eat;

and yet diet is seldom considered in these studies.

When diet is considered, the vast majority of dogs in the study are fed a commercial kibble diet — i.e., a highly processed, high-carbohydrate, and particularly a high-starch, diet that is low in protein for this carnivorous species.

I discuss at length how such diets contribute to behavioral reactivity in horses and dogs in Chapter 8 of The Highly Sensitive Dog. I also spend some time examining the question of whether dietary protein, and particularly tryptophan content, contributes to aggression in dogs.

[More on protein and aggression here.]

Highly processed, high-carbohydrate diets contribute to behavioral reactivity.

Puppyhood

One element that has not yet been thoroughly explored in dogs, but has been examined in horses, is the dog's diet and other influences in early puppyhood.

For example, the Alborada Well Foal study published in 2024 showed that a foal's gut microbiota is established by 2—4 weeks of age.

Leng J, Moller-Levet C, Mansergh RI, et al. Early-life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing. Scientific Reports, 2024; 14: 17124.

It's just a hunch, but I'm thinking that the window may be even shorter in puppies and kittens.

But even if it's similar in dogs and cats, that means the greatest window of opportunity we have to influence health and well-being via the gut microbiota closes before the puppy or kitten has even been weaned.

The greatest window of opportunity we have

closes before the puppy or kitten has even been weaned.

The reason I say that is because the gut microbiota research in other species shows three key things:

1. Every individual has their own unique microbiota that is distinctly different from all others.

2. Every individual's microbiota is not entirely knowable because it is not entirely fixed (i.e., static).

3. Every individual's microbiota is highly conserved, even in the face of massive challenge.

. . .

Notably, the Well Foal study also found that the gut microbiota established in early postnatal life (in the days and weeks after birth) determines disease risk and athletic performance later in life.

The Thoroughbred foals in this study were followed until they were 3 years of age, so the study included the first year of their racing careers. The researchers documented the incidence of respiratory disease, soft tissue injury, and orthopedic disease in these young athletes from birth to 3 years.

Interesting in its own right, this study got me wondering about the gut microbiota in early puppyhood and the risk for musculoskeletal disease in adult dogs, such as cranial cruciate ligament injury. Low microbial diversity in foalhood significantly increased the risk for all examined disease categories as the foal matured and started racing.

. . .

So, what dogs are fed in early puppyhood, and what their mothers were fed during pregnancy and lactation, sets them up for either a healthy, happy life or a troubled one.

What dogs are fed in early puppyhood,

and what their mothers were fed,

sets them up for life.

All is not lost, however, if we've missed that golden opportunity. What goes into your dog's mouth every day profoundly affects the composition of their gut's microbial community over time, and thus their gut-brain axis.

As diet is the topic of Chapter 8, I'll leave it here for now. I may not be able to help myself, though, so I may post some relevant excerpts from that chapter in future articles. Stay tuned…

What goes into your dog's mouth every day

profoundly affects their gut-brain axis.

. . .

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