## 3 Health Benefits of Probiotic Supplementation in Healthy Dogs  
### Microbiota Changes and Other Benefits in Healthy Dogs upon Probiotic Supplementation  
The supplementation of _Enterococcus fiecium_ NCIB 10415 (derived from healthy adult canine feces) (9.2 \(\times\) 10\({}^{9}\) CFU/dog/day) for 18 days reduced the fecal count of _Clostridium_ spp. in healthy dogs. _E. fiecium_ NCIB 10415 lowered the fecal count of _Campylobacter_ spp. and _Salmonella_ spp. in a few healthy dogs and insignificantly increased the fecal count of _Campylobacter_ spp. and _Salmonella_ spp. in the majority of the healthy dogs, indicating that _E. fiecium_ NCIB 10415 was not effective in inhibiting the growth of _Campylobacter_ spp. and _Salmonella_ spp. in the majority of healthy dogs. Although the study results suggested the beneficial effects of _E. fiecium_ NCIB 10415 in inhibiting the pathogenic _Clostridium_ spp., the effects of probiotics should be evaluated with caution [41] (Table 1). [PERSON] et al. [42] studied the effects of _Lactobacillus animalis_ LA4 (derived from healthy adult canine feces) on the composition and metabolism of dog intestinal microbiota under both in vitro and in vivo conditions. The in vitro evaluation showed that upon exposure of _L. animalis_ LA4 to adult dog fecal cultures, _L. animalis_ LA4 increased the count of _Lactobacillus_ and reduced the _Clostridium perfringens_ count. Moreover, LA4 increased the level of lactic acid in fecal cultures. LA4 reduced the ammonia concentration under in vitro conditions, while fecal concentration of ammonia was not influenced by LA4 under in vivo conditions. When healthy dogs (n = 9 adult) were fed with _L. animalis_ LA4 (10\({}^{9}\) CFU/g; 0.5 g per dog per day) for 10 days, the count of _Lactobacillus_ was increased, and the enterococci count was reduced. The in vivo evaluations of _Lactobacillus_ count also supported the findings of the in vitro experiments. The in vivo results showed that the strain LA4 could withstand the gastrointestinal environment and proliferate in the intestines of the studied adult dogs [42]. The supplementation of _Bacillus amploliquefaciens_ CECT 5940 and _E. fiecium_ CECT 4515 (0.2 g of a probiotic blend = 1 \(\times\) 10\({}^{8}\) CFU of each probiotic strain per dog per day; each strain = 5 \(\times\) 10\({}^{8}\) CFU per gram food) in the food of healthy dogs for 39 days did not affect the nutrient digestibility coefficients, fecal scores, or microbiota, whereas reduction was observed in the pathogenic clostridia count in the feces of healthy dogs administered probiotics. This study revealed that the supplementation of CECT 5940 and CECT 4515 reduced the pathogenic clostridia count without influencing food digestibility in healthy dogs [43]. A probiotic preparation (daily dose: 1 g of probiotic supplement/10 pounds of body weight) containing _Lactobacillus_ (>64 \(\times\) 10\({}^{9}\) CFU/g), _Bifidobacterium_ (30 \(\times\) 10\({}^{9}\) CFU/g), and _Bacillus_ species (24 \(\times\) 10\({}^{9}\) CFU/g) was orally administered to healthy female dogs for 14 or 28 days. The study results showed that probiotic supplementation orally for 14 or 28 days did not increase the vaginal lactic acid bacteria (LAB) in the healthy dogs [44]. [PERSON] et al. [45] investigated the effect of the supplementation of Queso Blanco cheese containing _Bifidobacterium longum_ KACC 91563 (5 \(\times\) 10\({}^{8}\) CFU/10 g cheese/kg of body weight/day) on intestinal microbiota and short chain fatty acids (SCFA) in healthy companion dogs. The fecal samples were collected at different stages such as before intake of cheese (week \(-\)2 and 0), during cheese intake (week 4 and 8), and after intake of cheese (week 10). The microbiota analysis revealed that the cheese containing KACC 91563 supplementation effectively reduced the Enterobacteriaceae and _Clostridium_ count and increased _Bifidobacterium_ in the feces of the companion dogs.