## 3 Health Benefits of Probiotic Supplementation in Healthy Dogs
### Microbiota Changes and Other Benefits in Healthy Dogs upon Probiotic Supplementation
The results showed that KACC 91563 intervention for eight weeks reduced the harmful bacterial load and increased the beneficial microbes in the dog intestine. Moreover, the SCFA, such as acetic and propionic acid levels, were raised during probiotic supplementation [45]. Similarly, Queso Blanco cheese containing _B. longum_ KACC 91563 (5 \(\times\) 10\({}^{8}\) CFU/10 g cheese/day) altered the fecal microbiota by effectively increasing the Bifidobacterium and decreasing _C. perfringens_, Enterobacteriaceae, _Collinesella_, _Blautia_, and _Fusobacterium_ in healthy beagle dogs. Overall, these results demonstrated that the supplementation of probiotic Queso Blanco cheese could improve the health status of companion dogs [45; 46]. A non-medicated milk replacement containing _Bacillus amyloidateaciens_ CECT 5940 (1 \(\times\) 10\({}^{9}\) CFU/g dry matter of probiotic product/dog/day) was administered to healthy dogs for 60 days, and the changes in microbiota were assessed. The results revealed that the bacillus count increased, and the coliform count decreased, in the probiotic-supplemented group compared to the control. The stool consistency was not affected by the probiotic supplementation. This study showed that CECT 5940 could survive the gastrointestinal passage and colonize in the dog intestine, further positively altering the intestinal microbial composition [47]. A probiotic food additive comprising _Lactobacillus casei_ Zhang, _Lactobacillus plantarum_ P-8, and _Bifidobacterium animalis_ subsp. _lactis_ V9 (equal proportion of 3 probiotic strains in a final concentration of 2 \(\times\) 10\({}^{9}\) CFU/g; Dosage: 2 g/day for each young dog; 4 g/day for each training dog; 10 g/day for each elderly dog) was administered to healthy dogs of different age groups (young, training, and an elderly group) for two months. probiotic supplementation increased the load of _Lactobacillus_ spp. and _Faecalibacterium prausnitzzi_ but decreased the abundance of _Sutterella stercorianisin_ and _Escherichia coli_ in the feces of the experimental elderly dogs. Moreover, the induction of cytokines and antibodies was positively regulated in the probiotic-treated group. Two months of probiotic treatment also shifted the gut microbiota of elderly dogs towards the composition of microbiota found in younger dogs at the end of the experimental study. Changes in some microbial species showed a correlation with some immune factors (such as fecal secretory IgA, serum IgG, TNF-\(\alpha\)), indicating that probiotic intervention governs the immune system by changing the gut's microbial composition in dogs [48]. Kefir, a probiotic dairy product (200 mL of kefir/day; Kefir contains LAB (9.32 \(\pm\) 0.23 log CFU per mL), and yeast (7.12 \(\pm\) 0.36 log CFU per mL)), was administered orally to healthy dogs (n = 6 adult; 2 females, 4 males) for two weeks, and the changes in microbiota were assessed. The load of _Fusobacteria_, _Clostridaceae_, _Fusobacteriaceae_, _Huminococcaceae_, and the _Firmicutes_: _Bacteroidetes_ ratio decreased, whereas quantities of LAB, _Sutterellaceae_, _Prevotellaceae_, and _Selenomonadaceae_ and the LAB: _Enterobacteriaceae_ ratio increased in the group that consumed kefir. This study revealed that kefir supplementation effectively improved the dogs' intestinal microbiota, and that kefir could be used as a functional food to improve dogs' health [49]. _Lactobacillus kefiri_ (10\({}^{7}\) cells per day) was administered to healthy dogs (n = 10) for 30 days. The changes in gut microbiota composition were assessed in the fecal samples of the experimental dogs. The results suggested that the fecal microbiota of the experimental dogs were not influenced upon administration of _L. kefiri_[50]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref. ** & **Model** & **Probiotic Used** & **Dose per Animal** & **Duration** & **Effect of Probiotic Supplementation** \\ \hline \multirow{3}{*}{[41]} & Healthy dogs & _Enterococcus facicum_ & & & Reduced the fecal count of _Clostitrium_ spp.