Is raw-feeding good for the gut microbiome?

Dr Emma Bermingham has recently completed a review on the effects of raw-meat diets on the gut microbiota of cats and dogs for the New Zealand Veterinary Journal, funded by HPNZ.


The biggest take home message is how little we really know and understand about the gut microbiome and its metabolic and physiologic effects in carnivores such as cats and dogs; so there is significant scope to better understand how we feed our carnivorous companion animals.


The article starts by reviewing the nutritional requirements of domestic cats and dogs, then reviews the nutritional impacts and risks of feeding raw-meat diets. Discussion around gut microbiome diversity, composition, and its metabolic function follows, demonstrating what an important area of study this is.


Several major themes arose around the impacts of feeding raw meat diets to cats and dogs. Firstly, the lack of standardisation of what “raw-feeding” is (diets can vary from incomplete, unprocessed to balanced and processed) impairs the interpretation of the microbial and nutritional effects of these diets. The nutritional and zoonotic risks associated with incomplete, unprocessed diets (both with nutritional adequacy and zoonotic transfer of pathogens) are perceived to be higher compared to commercial, processed diets; however, there is a lack of published information to support this.


Secondly, although studies have shown that raw meat diets promote gut microbial communities dominated by Fusobacterium spp. and Clostridium spp., the metabolic and physiological impacts of these bacterial strains on the host are unclear. In this vein, microbiome data have generally been interpreted in the context of omnivore-derived references, which may not be applicable to the carnivore microbiome.


Thirdly, most studies provide little dietary information (macro- and micro-nutrient composition) or data on physiological impacts (e.g. faecal metabolites, faecal health score) to allow deeper conclusions into the consequences of these diets on the carnivore host.


Thus, there is still significant scope to better understand the interactions between raw meat diets, cats and dogs and their gastrointestinal microbiota to promote better nutrition in carnivorous companion animals.