Evaluation of a Novel Compound Probiotic Paste Containing Canine-Derived Vitamin B12-Producing Limosilactobacillus Reuteri.

Chronic diarrhea in pets features high incidence, often causing vitamin B12 deficiency. Probiotics, which can alleviate or even treat chronic diarrhea by improving intestinal microbial balance, have shown promise. Previously, our laboratory isolated a strain of Limosilactobacillus reuteri (CLAB) with vitamin B12-producing capability from canine feces. However, it had suboptimal palatability and insufficient efficacy against chronic diarrhea and vitamin B12 deficiency. In this study, the CLAB was combined with Enterococcus faecalis and Saccharomyces cerevisiae to formulate a compound probiotic paste. The properties of the paste were comprehensively evaluated via a series of experiments including sensory evaluation, pH testing, microbial colony counting, palatability tests, disease activity index scoring, histopathological analysis, biochemical indicator analysis, and RNA quantification. The results demonstrated that the paste exhibited good stability, safety, and favorable palatability in both dogs and cats. Meanwhile, it significantly alleviated chronic diarrhea and vitamin B12 deficiency in mice. Specifically, the high-dose compound probiotic paste decreased myeloperoxidase and malondialdehyde levels in diarrheic mice from approximately 15.9 and 2.5 nmol/mgprot to about 4.2 and 1.7 nmol/mgprot; increased the total antioxidant capacity content and superoxide dismutase activity from approximately 0.5 nmol/mgprot and 1.0 U/mgprot to about 0.6 nmol/mgprot and 1.6 U/mgprot; and downregulated the relative mRNA levels of interleukin-6, interleukin-1β and tumor necrosis factor-α from approximately 2.1, 2.1 and 2.7 to about 1.2, 1.1 and 1.3, respectively. In conclusion, this study supports the potential use of the compound probiotic paste for preventing and treating chronic diarrhea and improving vitamin B12 deficiency in pets.