Research is yielding ever more insights into the gut microbiome, the trillions of microorganisms that inhabit the digestive tract. Exciting scientific progress has been made in this area, with studies revealing the effects of these microorganisms on diverse organs including the skin, heart and kidneys (Blake and Suchodolski, 2016). More recently, new evidence has shed light on the microbiome’s effect on mental well-being, specifically anxiety behaviours in dogs (Trudelle-Schwarz McGowan, 2018). These fascinating new discoveries open up new possibilities for supporting anxious dogs via nutritional means.
The gut microbiome
The gut contains a remarkable number of microorganisms; it has been estimated that there are roughly as many bacterial cells in the digestive tract as there are host cells in the whole body (Sender et al., 2016).
For many years, we have known that these microorganisms are important for gut health, with their roles in vitamin synthesis and mineral absorption, defending against pathogens and directly nourishing enterocytes (Blake and Suchodolski, 2016).
Beyond the digestive tract, however, the gut microbiome has a whole host of other functions. It is important for the health of the immune system and also has a range of effects on other organs including the kidneys, heart and skin. In fact, gut microbiome disruption has been linked with a variety of extra-intestinal diseases including diabetes, atopic dermatitis, impaired immune function and obesity (Blake and Suchodolski, 2016).
Gut microbiome disruption has been linked with a variety of extra-intestinal diseases including diabetes, atopic dermatitis, impaired immune function and obesity (Blake and Suchodolski, 2016).
As well as this myriad of effects on physical health, growing evidence suggests that the gut microbiome can also have an impact on mental well-being. Specifically, it has been implicated in anxiety behaviours.
The gut microbiome and anxiety
A fascinating initial study in this area was conducted using faecal microbial transplantation in a mouse model. Remarkably, the study found that it was possible to pass anxiety behaviours between different mice simply by transferring their intestinal microbes (Collins et al., 2013). This finding highlighted the scope of this field, raising the question of how we can modify the gut microbiome clinically to affect anxiety.
The clinical implications were later explored in a blind placebo-controlled crossover study conducted by Purina PetCare scientists. This study evaluated the impact of a particular probiotic, Bifidobacterium longum (BL999), on behaviour in anxious Labradors. When supplemented with the probiotic for six weeks, dogs showed a reduction in anxiety behaviours which included barking, jumping, spinning and pacing, as well as exhibiting lower salivary cortisol levels and heart rates (Trudelle-Schwarz McGowan, 2018).
When supplemented with the [Bifidobacterium longum] probiotic for six weeks, dogs showed a reduction in anxiety behaviours which included barking, jumping, spinning and pacing
These findings are significant as they illustrate the potential for us to affect anxiety by nutritional means. This will be of great interest to clinicians, especially since anxiety in dogs is becoming a bigger issue in light of the COVID-19 pandemic.
The growing issue of canine anxiety
In a recent survey of over 1,000 dog owners across the UK, carried out by Opinion Matters on behalf of Purina, anxiety was shown to be remarkably common, with nearly half of respondents (48 percent) reporting that their dogs had shown signs of stress or anxiety. Additionally, 28 percent of owners said that their dogs had become more anxious over the last year, suggesting that the upheaval of the pandemic has made this issue even more common. As we return to “normal” behaviours, 36 percent of dog owners stated that they are concerned about their pet’s health and well-being (Opinion Matters, 2021).
Concern about canine anxiety is well founded, as the issue has a number of adverse consequences. Anxiety can be very distressing for pets and can cause physical effects including gastrointestinal disturbances and increased susceptibility to illness (Landsberg et al., 2012; Tanaka et al., 2012). The issue can also place great strain on the pet–owner bond: anxiety has been reported to account for up to 70 percent of canine behavioural disorders (Beata et al., 2007), which are unfortunately a common reason for relinquishing pets to shelters (Salman et al., 2000).
The new research linking nutrition and anxiety could be of great value in highlighting a potential new avenue of support for these patients
Given the potentially serious consequences of anxiety and its high prevalence, the new research linking nutrition and anxiety could be of great value in highlighting a potential new avenue of support for these patients.
Adding to the support for anxious dogs
Addressing canine anxiety often requires a multimodal approach. Behavioural support is key, and owners benefit from advice on how to respond to the issue, as well as how to adjust their routines and the environment to mitigate problems. In some cases, a dedicated support programme from a qualified animal behaviourist can be very helpful. As well as behavioural support, clinicians may choose to factor in the use of pheromones, anxiety-relieving supplements or devices and sometimes medication as appropriate. Alongside these approaches, it is likely that support of the gut microbiome will become increasingly recognised as an element of the management plan as scientists learn more about this fascinating field.
For pets to benefit from the new insights in this field, it is important to raise awareness among owners. Ultimately, the aim is to help more pets enjoy the physical and mental benefits of good-quality nutrition.