Diarrhea is a prevalent issue in animal shelters, affecting both dogs and cats and stemming from various factors such as stress, dietary changes, and infectious agents like bacteria, viruses, and parasites. This condition can significantly impede the adoption process, strain shelter resources, and in severe cases, lead to euthanasia. While shelters implement enrichment and stress-reduction strategies, the need for additional measures to mitigate diarrhea incidence persists. Probiotics, defined as live microorganisms conferring health benefits, have emerged as a potential solution. Specifically, Enterococcus faecium SF68 is a well-researched probiotic known for its positive effects on the gastrointestinal tract. Studies have indicated its ability to influence gut microbiota, increase beneficial bacteria, and potentially modulate the immune system. Anecdotal evidence suggests shelters use this probiotic to reduce diarrhea, but empirical, controlled research in this specific environment has been lacking. This study aimed to rigorously investigate the hypothesis that dogs and cats in an animal shelter receiving Enterococcus faecium SF68 would experience fewer episodes of diarrhea lasting two days or more compared to a placebo group.
Materials and Methods
Animals and Housing
The study included 217 cats and 182 dogs housed in separate, identical rooms within an animal shelter. The animal population was dynamic, with animals entering and leaving throughout the four-week study periods. Dogs were individually housed in runs, while cats were housed in cages, with specific room assignments for domesticated versus feral or aggressive cats. Signalment data (age, sex, breed) were recorded, though detailed history was often unknown. All animals received a standardized commercial dry maintenance diet and had ad libitum access to water. Daily disinfection of cages and runs was performed.
Experimental Design
This double-blind, placebo-controlled study spanned three periods of four weeks each. Period 1 served as a baseline to establish normal diarrhea rates per room without intervention. In Periods 2 and 3, animals in one room of each species received Enterococcus faecium SF68 (approximately 1g daily, containing 2.1 x 10^9 CFU/g) mixed with a palatability enhancer and food, while the other room received only the palatability enhancer as a placebo. Treatments were administered by a blinded individual. A one-week washout period between Periods 2 and 3 allowed for potential environmental decontamination. Treatment rooms were alternated between Periods 2 and 3 to mitigate any room-specific effects.
Data Collection and Stool Analysis
Fecal scores (FS) were assigned daily using the Nestle Purina Fecal Scoring System (FS 1–3: normal; FS 4–7: diarrhea). Stools with FS ≥4 were saved for analysis. Fecal samples were collected from animals with diarrhea (FS ≥4) and from animals with normal stools (FS ≤3) in the same room on the same day. These samples were transported to Colorado State University for analysis of enteric parasites using sugar solution centrifugation and immunofluorescence kits for Giardia spp. and Cryptosporidium spp.
Statistical Analysis
Data were stratified to include animals housed for 2–7 days, excluding the first day of data collection due to unknown entry times. The primary outcome was the percentage of animals experiencing diarrhea for ≥2 days. A generalized linear mixed model with a binomial distribution was used to compare treatment groups, with treatment as a fixed effect and room as a random effect. Parasitism prevalence rates were compared using Fisher’s exact test. Significance was set at P < .05.
Results
Cats
A total of 222 cats had fecal samples available. Parasites were detected in 14.9% of cats, with no correlation between the presence of parasites and diarrhea. Among cats housed for 2–7 days, 130 received SF68 and 87 received the placebo. While overall diarrhea incidence did not differ significantly between groups (P = .5295), the percentage of cats experiencing diarrhea for ≥2 days was significantly lower in the SF68 group (7.7%) compared to the placebo group (20.7%) (P = .0297). Only a small number of cats in both groups with prolonged diarrhea tested positive for intestinal parasites.
Dogs
Fecal samples from 91 dogs were analyzed, with 15.4% testing positive for at least one infectious agent. No significant difference in parasite prevalence was found between rooms. Of the dogs included in the analysis, 102 received SF68 and 80 received the placebo. Diarrhea incidence was low in both groups, with only one dog in each group experiencing diarrhea for ≥2 days. Consequently, no statistical differences were detected between the SF68 and placebo groups for dogs.
Discussion
The study demonstrated that cats readily consumed both the SF68 probiotic and the placebo without adverse effects. The key finding was the significant reduction in the duration of diarrhea (≥2 days) in cats supplemented with SF68, supporting the hypothesis. While statistical differences were not observed in dogs, this was likely due to the low incidence of prolonged diarrhea during the study period. This low incidence in dogs may be attributed to the consistent feeding of a standardized diet, a change from previous years where variable food donations were used.
The findings in cats suggest that SF68 may exert its beneficial effects through colonization inhibition of pathogenic microorganisms in the gastrointestinal tract, rather than solely through systemic immune enhancement, given the short duration of probiotic supplementation. The study also noted that the presence of gastrointestinal parasites did not correlate with diarrhea in this population, which was not unexpected as many identified parasites can colonize healthy animals and are not always associated with clinical signs.
Reducing diarrhea in shelter animals is crucial for improving their welfare, expediting adoption, and conserving shelter resources. While the cost-effectiveness of probiotic supplementation needs to be evaluated by individual facilities, this study provides evidence for the potential benefit of Enterococcus faecium SF68 in managing diarrhea in shelter cats. Further research, potentially with a larger sample size and longer duration, may be warranted to explore its effects in shelter dogs.
