Utilizing psychobiotics to improve pet mood

Nutritional scientists believe that good health starts in the gut. This is because the gut is the first point of health impact for all items ingested by a pet. Once in the gut, the animal’s body begins to react to those substances. Importantly, what happens in the gut does not stay localized to the gut. For example, since 70% of the lymph tissue is associated with the gut, the body’s immune system is highly influenced by gut events.

Gut-brain axis

Likewise, there is an association between the gut and the brain which has been termed the ‘gut-brain axis’. Cells that line the gut ‘sample’ what is occurring inside the gut (or lumen) and send signals back to the brain. This occurs indirectly through the production of hormones or directly through the vagal nerve which connects the gut to the brain. This ongoing gut sampling and signaling phenomenon thus affects brain perception.

Examples in humans

A need to understand ways to address mood and psychological addiction in humans has arisen because people struggle with depression, undergo recovery from drug addiction and experience cognitive decline with aging, for instance. As a result, academic research into how to favorably affect brain function has accelerated. This research has produced insights into what have been termed ‘psychobiotics’.

The term psychobiotics usually relates to a group of probiotics that are orally ingested and then result in some effect on the brain. However, other gut-active dietary components (e.g. prebiotics, postbiotics) have also been lumped into this category. As one example, a clinical study in humans demonstrated a blend of probiotics that improved ‘sad mood’. Other examples in humans involve certain strains of lactobacilli having been shown to lessen anxiety or improve cognition and reduce cortisol, which is a stress hormone.

Microbiota composition in dogs

Dysbiosis, i.e. an abnormal/unhealthy composition of intestinal microbiota, has been associated with neuropsychiatric diseases in humans. Dysbiosis of the gut in dogs has also been described and, to date, has been associated with gut inflammation. Differences in microbiota composition have been shown in dogs of varying behavioral types. Since aggressive dogs have been shown to express significantly different microbiota compositions from phobic or normal dogs, it could be concluded that the composition of intestinal microbiota may influence mood and behavior in dogs.

Bifidobacterium longum (B. longum) is one probiotic that has been studied for its effects on various brain-related disorders. In humans, B. longum has been shown to: 1) improve cognition in Alzheimer’s patients, 2) improve sleep during periods of stress, and 3) be associated with reduced stress and anxiety when present in the gut. Recently, Nestlé Purina has promoted a ‘calming’ supplement containing B. longum for dogs and cats. Interestingly, it is purported that the mechanism for why this happens is through the vagal nerve, which communicates between the gut and the brain. B. longum may also impact tryptophan levels in the body, a precursor to a neurotransmitter involved with the gut-brain axis.

Probiotics are not the only means to affect behavior through the biotics route. Researchers have shown that feeding a postbiotic consisting of inactivated L. fermentum and L. delbruekii was able to improve sociability in mice and to lower stress hormones. This change was explained by subtle shifts in the gut microbiota.

Growing evidence

In sum, the evidence for the use of psychobiotics in humans to improve brain function (e.g. cognition, mood, sleep, etc.) by impacting gut-level events as well as communication mechanisms to the brain, is rapidly growing. Early evidence in dogs confirms gut microbiota changes between aggressive and phobic or normalbehavior dogs. As such, it is reasonable to consider the role of psychobiotics in impacting gut-level events that could improve brain function in dogs and cats. Various large pet product manufacturers are already taking advantage of these findings. Is your company?