Improving pets’ well-being via the brain-gut axis

An animal’s gut plays an important role in pet health and well-being.

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“Well-being” can be described as the main concern of any pet owner. But what does well-being mean, and how can we define pet well-being? There are four main principles commonly used to assess animal well-being: good feeding, good housing, good health and appropriate behavior. Some of these parameters can be linked to a central organ that is often underestimated — the gut — and its billions of inhabitants: the microbiota. Is there a way to improve pets’ well-being by shaping their gut microbiota with natural feed ingredients?

The microbiota: a key player

The digestive tract of dogs and cats harbors a complex community of microorganisms, called the gut microbiota, that plays a crucial role on the host’s overall health. Recent developments in the field of sequencing techniques, with the “omics” revolution, have considerably enlarged our understanding of the microbiota and its potential functions.

The gut microbiota is a dynamic system with great intra- and inter-individual variations. Its three main functions are keys to ensuring the maintenance of the overall health of the host’s gastrointestinal tract (GIT): 1. metabolic function, 2. protective function and 3. structural function.

The complex interactions among the microbiota, the host immune system and the host’s genetics influence the balance between health and disease. Genetics, age, environment, antibiotics and diet are some of the factors recognized as affecting the microbiota. For example, it was shown in dogs that a relatively small amount of dietary fiber was able to detectably change the structure of the gut microbiota. In the same way, functional ingredients such as prebiotics and probiotics — well documented to influence the microbiota of many species — have shown effects on pets’ microbiota too, as illustrated by a positive study in dogs with live yeast S. cerevisiae var. boulardii on the prevention of antibiotic-associated diarrhea (Aktas et al., 2007).

Probiotics studies in pets are still scarce, but the amount of literature on the mode of action of many probiotic strains and effects in humans and other mammals are fairly good indicators of their potential for dogs and cats. One can only expect this area of study to grow.

Some GIT disorders, both acute and chronic, are well known to be associated with alterations of the microbial communities, but it is now increasingly documented that disorders beyond the GIT such as obesity, atopic dermatitis or central nervous disorders can also be linked to changes in the microbiota. In this context, functional ingredients that are known to influence the microbiota composition such as prebiotics, probiotics and other nutritional interventions could represent alternative approaches to tackle these issues.

The second brain: control of well-being

The brain-gut axis: This is certainly one of the newest and most promising areas of research in microbiota and probiotics. In 2013, the team of John Cryan coined the term “psychobiotics” to translate this idea, defining this new class of probiotics as a “live organism that, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness” (Dinan et al., 2013). In a world where an estimated 29 percent of pet dogs exhibit signs of anxiety (probably a gross underestimate), and where the great part of up to 70 percent of dogs’ behavioral disorders can be attributed to some form of anxiety (Beata et al., 2007), the psychobiotic approach certainly makes sense for pet well-being too.

The crucial role of the microbiota in the brain-gut communication axis has now been demonstrated, as well as its role in anxiety behavior, in humans and rodents. The potential of probiotics to influence this brain-gut axis is a growing field of evidence with first animal study published in 2006 (Zareie et al., 2006). A few years later the first human studies showed a probiotic supplement can effectively alleviate both physiological and psychological symptoms of chronic stress (Diop et al., 2008; Messaoudi et al., 2010). To date, more than 50 published studies have evaluated the link between probiotics supplementation and the brain-gut axis, including at least 17 human clinical studies.

A recent study in dogs indicates that 90 percent of dogs supplemented with the probiotic B. longum showed improvement in day-to-day anxious behavior including reduction of barking, jumping, spinning and pacing as compared to a placebo. In addition, around 80 percent showed a decrease in heart rate and an increase in heart rate variability, indicating a more positive response to anxiety (McGowan, 2016). Such a preliminary study is very positive in showing a positive effect on both behavioral and physiological signs of anxiety in dogs.


Shaping the intestinal microbiota through supplementation with specific functional ingredients could be a way to optimize pets’ overall health and, consequently, improve their well-being.

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