Clostridium hiranonis was first identified for its ability to perform bile acid 7α-dehydroxylation [1] - this is a chemical modification of primary bile acids produced by your dog’s liver into physiologically crucial secondary bile acids. These secondary bile acids are how bacteria communicate with each other in the dense ecosystem of the mammalian gut. At least nine, independent, peer reviewed studies have correlated a lack of Clostridium hiranonis with canine GI problems [2-10]. Beyond correlation, a recent study revealed that Clostridium hiranonis and the secondary bile acids it produces are responsible for the improvement in symptoms from dogs suffering from chronic enteropathy [11]. In 2020, advances in molecular biology led to a proposal to reclassify this organism into the novel genus Peptacetobacter, so you may see this organism called “Peptacetobacter hiranonis” in more recent literature [12].

1. Hirano, S. E. I. J. U., et al. "Isolation and characterization of thirteen intestinal microorganisms capable of 7 alpha-dehydroxylating bile acids." Applied and environmental microbiology 41.3 (1981): 737-745.
2. AlShawaqfeh, M. K., et al. "A dysbiosis index to assess microbial changes in fecal samples of dogs with chronic inflammatory enteropathy." FEMS Microbiology Ecology 93.11 (2017): fix136.
3. Pilla, Rachel, et al. "Effects of metronidazole on the fecal microbiome and metabolome in healthy dogs." Journal of veterinary internal medicine 34.5 (2020): 1853-1866.
4. Giaretta, Paula R., et al. "Comparison of intestinal expression of the apical sodium‐dependent bile acid transporter between dogs with and without chronic inflammatory enteropathy." Journal of veterinary internal medicine 32.6 (2018): 1918-1926.
5. Chaitman, Jennifer, et al. "Fecal microbial and metabolic profiles in dogs with acute diarrhea receiving either fecal microbiota transplantation or oral metronidazole." Frontiers in veterinary science 7 (2020): 192.
6. Stone, Nathan E., et al. "Domestic canines do not display evidence of gut microbial dysbiosis in the presence of Clostridioides (Clostridium) difficile, despite cellular susceptibility to its toxins." Anaerobe 58 (2019): 53-72.
7. Cigarroa A, Suchodolski JS. Assessing the development of the postnatal canine gastrointestinal microbiome utilizing the dysbiosis index. In: Proceedings of the National Veterinary Scholars Symposium. College Station, TX (2018).
8. Li, Qinghong, et al. "Gut Dysbiosis and Its Associations with Gut Microbiota-Derived Metabolites in Dogs with Myxomatous Mitral Valve Disease." Msystems 6.2 (2021).
9. Tysnes, Kristoffer Relling, et al. "Pre-and Post-Race Intestinal Microbiota in Long-Distance Sled Dogs and Associations with Performance." Animals 10.2 (2020): 204.
10. Vázquez-Baeza, Yoshiki, et al. "Dog and human inflammatory bowel disease rely on overlapping yet distinct dysbiosis networks." Nature microbiology 1.12 (2016): 1-5.
11. Wang, Shuai, et al. "Diet-induced remission in chronic enteropathy is associated with altered microbial community structure and synthesis of secondary bile acids." Microbiome 7.1 (2019): 1-20.
12. Chen, Xiao-Jiao, et al. "Characterization of Peptacetobacter hominis gen. nov., sp. nov., isolated from human faeces, and proposal for the reclassification of Clostridium hiranonis within the genus Peptacetobacter." International journal of systematic and evolutionary microbiology 70.5 (2020): 2988-2997.

Megamonas funiformis was first isolated in 2008 [1] and has since been identified as a native canine gut organism in healthy dogs [2]. Megamonas funiformis readily ferments glucose into the short chain fatty acids propionate and acetate [1], which directly stimulate the canine smooth muscle tissue in the intestine to improve digestion [3]. In addition to this direct effect on digestion, there is evidence that Megamonas creates carnitine which may help protect your canine from leaky-gut [4]. Megamonas is depleted in dogs with inflammatory bowel disease [5,6] - the same was also found for cats [7] and humans [8], showcasing the long history of Megamonas in gut health.

1. Sakon, Hiroshi, et al. "Sutterella parvirubra sp. nov. and Megamonas funiformis sp. nov., isolated from human faeces." International journal of systematic and evolutionary microbiology 58.4 (2008): 970-975.
2. Hand, Daniel. Exploring the breadth and depth of diversity within the canine gut microbiome. Diss. University of Birmingham, 2011.
3. McManus, Catherine M., et al. "Effect of short-chain fatty acids on contraction of smooth muscle in the canine colon." Journal of the American Veterinary Medical Association 63.2 (2002): 295-300.
4. Li, Qinghong, et al. "Gut Dysbiosis and Its Associations with Gut Microbiota-Derived Metabolites in Dogs with Myxomatous Mitral Valve Disease." Msystems 6.2 (2021).
5. Maldonado-Contreras, Ana, et al. "Dysbiosis in a canine model of human fistulizing Crohn’s disease." Gut Microbes 12.1 (2020): 1785246.
6. Vázquez-Baeza, Yoshiki, et al. "Dog and human inflammatory bowel disease rely on overlapping yet distinct dysbiosis networks." Nature microbiology 1.12 (2016): 1-5.
7. Suchodolski, Jan S., et al. "The fecal microbiome in cats with diarrhea." PloS one 10.5 (2015): e0127378.
8. Zhang, Xu, et al. "Widespread protein lysine acetylation in gut microbiome and its alterations in patients with Crohn’s disease." Nature communications 11.1 (2020): 1-12.

Enterococcus faecium is a highly prevalent and widely studied commensal in both animals and humans that was originally discovered in feces [1]. In vivo studies have shown that Enterococcus faecium can bind to mucosal surfaces in the intestine [2] and outcompete pathogens leading to reduced pathogenic load after as little as one week of probiotic use [3]. Enterococcus faecium has also been shown to reduce the severity of diarrhea in shelter animals [4,5]. Dogs fed a daily probiotic of Enterococcus faecium had higher fecal IgA levels and a higher proportion of mature B cells [6]; in other words, daily dosing with this commensal bacteria creates a more robust canine immune system. The beneficial effects of Enterococcus faecium on the host immune system have also been observed in mice [7], pigs [8] and cats [9].

1. Holzapfel, Wilhelm, et al. "Enterococcus faecium SF68 as a model for efficacy and safety evaluation of pharmaceutical probiotics." Beneficial microbes 9.3 (2018): 375-388.
2. Strompfová, Viola, Andrea Lauková, and Arthur C. Ouwehand. "Selection of enterococci for potential canine probiotic additives." Veterinary Microbiology 100.1-2 (2004): 107-114.
3. Marciňáková, M., et al. "Oral application of Enterococcus faecium strain EE3 in healthy dogs." Folia microbiologica 51.3 (2006): 239.
4. Bybee, S. N., A. V. Scorza, and M. R. Lappin. "Effect of the probiotic Enterococcus faecium SF68 on presence of diarrhea in cats and dogs housed in an animal shelter." Journal of Veterinary Internal Medicine 25.4 (2011): 856-860.
5. Fenimore, Audra, Laura Martin, and Michael R. Lappin. "Evaluation of metronidazole with and without Enterococcus faecium SF68 in shelter dogs with diarrhea." Topics in companion animal medicine 32.3 (2017): 100-103.
6. Benyacoub, Jalil, et al. ""Supplementation of food with Enterococcus faecium (SF68) stimulates immune functions in young dogs."" The Journal of nutrition 133.4 (2003): 1158-1162.
7. Sun, Peng, Jiaqi Wang, and Yanmei Jiang. "Effects of Enterococcus faecium (SF68) on immune function in mice." Food chemistry 123.1 (2010): 63-68.
8. Szabó, István, et al. "Influence of a probiotic strain of Enterococcus faecium on Salmonella enterica serovar Typhimurium DT104 infection in a porcine animal infection model." Applied and environmental microbiology 75.9 (2009): 2621-2628.
9. Veir, Julia K., et al. "Effect of supplementation with Enterococcus faecium (SF68) on immune functions in cats." Veterinary therapeutics: research in applied veterinary medicine 8.4 (2007): 229-238.