Sessions

A balanced microbial ecosystem is vital for maintaining host health and homeostasis. Disruption of microbiome structure, composition, and function (dysbiosis) plays a key role in the development and persistence of numerous pathological processes. Fecal microbiota transplantation (FMT) is one of the most effective methods for restoring eubiosis. Although rectal enemas are the most common in veterinary medicine, oral capsules make this procedure not only simpler but also more widely accessible.

Our study aimed to investigate the effects of lyophilized FMT capsules, produced following human medicine protocols, in healthy dogs. Our study included the selection and screening of donor and recipient dogs, incorporating antimicrobial susceptibility testing, which represents a unique, new additional criterion to the internationally used guideline. During the trial, animals received one FMT capsule daily for 30 days. Throughout this period, clinical health status and the potential occurrence of side effects were assessed through regular consultations with the owners. Furthermore, changes in gut microbiome composition were analyzed by determining the dysbiosis index (DI) and minimum inhibitory concentration (MIC) values from fecal samples.

During pre-screening, two out of 13 potential donors and 21 out of 34 recipient candidates met the inclusion criteria. Donors and recipients were clinically healthy, free of gastrointestinal parasites and enteropathogenic bacteria. Additionally, the donor did not carry multidrug-resistant (MDR) bacterial strains. At baseline, all recipient dogs had DI values within the reference range. Although mean DI values showed a slight increase during the study, they remained within the reference range throughout, indicating no clinically pathological shift. A total of nine dogs showed a DI value of zero or above at least at one time point, however, severe dysbiosis was not observed at any sampling point in any animal. Furthermore, MIC values did not indicate the transfer of antimicrobial resistance genes. The animals tolerated capsule administration well, and no side effects were observed.

In conclusion, the encapsulation method developed for human medicine can be successfully applied in dogs, without causing clinical side effects or inducing dysbiosis in animals with a healthy gut microbiome. Our results provide the foundation for the safety assessment of this FMT formulation, promoting the production and routine therapeutic use of the first FMT capsule manufactured in Hungary for canine patients.

Keywords: gut microbiome, dog, dysbiosis, fecal microbiota transplantation (FMT), lyophilized, capsule