I mentioned in my opening editorial that I was recently exposed to content well outside of my comfort zone. Hang onto your hats, because I am about to bring small animal medicine into the conversation! A recent article in JAVMA (Volume 263: Issue S2) touched on a topic that I have been interested in for several years. It explores microbiome therapeutics and is entitled “The heroes within: utilizing the gut microbiome, microbiome therapeutics, and fecal microbiota transplant in managing companion animal health and disease.” A few years ago, we conducted a study using fecal microbiota transplants in calves. Although it did not prove to be the panacea we were hoping for calf GI disease, it did lead to some interesting findings. The FMT product made from healthy donor calves was rich in organisms typically known for their beneficial probiotic properties, but it did not prevent or ameliorate GI disease in dairy calves. In fact, calves that received FMT were less likely to recover from GI disease and more likely to die due to GI disease complications, which we think was due to our inability to remove pathogens such as rotavirus, coronavirus, and cryptosporidium from the product. Our results indicated the need to have an established protocol when developing FMT products, based on rigorous inclusion and exclusion criteria for the selection of FMT donors free of potential pathogens, and no history of disease or antibiotic treatment.
But I digress. The JAVMA article mentioned above is a narrative review that provides the current definition of the gut microbiome, the organisms comprising the theater, and their contributions to host homeostasis. It surmises that integrating microbiome therapeutics into clinical practice can be achieved through a multimodal approach that utilizes diet, prebiotics, probiotics, postbiotics, bacteriophages, and fecal microbiota transplant to modulate the microbiome balance and restore eubiosis to patients in dysbiotic states. Whether we talk about small or large animals, emerging research increasingly implicates the gut as a central player in health and disease, identifying the gut microbiome as a key factor that warrants deeper consideration. The author points out that the concept of “microbiome medicine” is not novel, but its integration into mainstream clinical practice has been restricted by a limited number of large-scale research studies validating its efficacy. As a result, it has previously been relegated to the realm of complementary or alternative approaches rather than being adopted as a first-line modality. Furthermore, emerging challenges in veterinary medicine, such as the overuse of antibiotics and the consequent rise in antimicrobial resistance, regulatory bans on the routine use of antimicrobial growth promoters in food-producing animals, and a general shift toward preventive and integrative health strategies, are prompting a reevaluation of this paradigm. Overall, these developments underscore the growing relevance of microbiome-focused interventions in all aspects of veterinary medicine.
I like this JAVMA article because it does a nice job outlining a number of important concepts applicable to all veterinarians. In particular, it highlights a couple of intriguing points that raise some interesting questions.
- Host-microbiome interactions are not limited to immediate physiological outcomes and are the product of long-term coevolutionary dynamics. The composition and diversity of microbial communities have evolved in tandem with their host species, exerting their influence on host gene expression, development, and fitness. Conversely, host genetic, environmental, and behavioral factors impose selective pressures that shape the survival, adaptation, and diversification of resident microbial taxa.
- Species specificity resulting from the coevolution of the microbiota and host may enhance the successful engraftment of key bacterial species and promote greater microbial diversity.
Is it possible that these coevolutionary adaptations go beyond host species to influence farm-level responses? For example, is it possible that farm-specific microbiotas influence outcomes at calf ranches? Are certain farms more or less susceptible to adult cow diseases such as winter dysentery caused by coronavirus because of the prevalent microbiota? Can disease resistance and tolerance be baked into the gut microbiome? Veterinary medicine is still in the early stages of exploring GIT microbiome therapeutics and implementing their full potential. There is no doubt that future research and development efforts will focus on characterizing the microbiome compositions of other body systems as well (such as the blood, lungs, skin, oral cavity, and eyes) and explore how these microbiomes are linked to various disease states.
Although the purpose of this JAVMA narrative review was to present current research regarding the inclusion of dysbiosis diagnosis and the application of microbiome therapeutics in the management of companion animal health and disease, I think it provides useful food-for-thought for the large animal practitioner as well. Those of us with a particular affinity for ruminants are acutely aware of the outsized impact of the gut microbiome, but it never hurts to approach an issue from a different angle. Acknowledging the role of the gut microbiome helps us prioritize this complex ecosystem across both preventative and therapeutic strategies. It is likely that the future advancement of therapies such as synbiotics (combinations of probiotics, prebiotics, and postbiotics) along with the identification of novel bacterial species for next-generation probiotic formulations will offer veterinary clinicians powerful new tools for the prevention and management of a wide range of disease states, further strengthening the promise of microbiome-focused therapies.