Pilot study to evaluate the effect of oral supplementation of Enterococcus faecium SF68 on cats with latent feline herpesvirus 1

Feline herpesvirus 1 (FHV-1) infection is extremely common in cats and is frequently associated with morbidity because of recurrent ocular and respiratory clinical signs of disease. Enterococcus faecium strain SF68 is an immune-enhancing probiotic used as a dietary supplement. In this pilot study, 12 cats with chronic FHV-1 infection were administered either SF68 or a placebo, monitored for clinical signs of disease, monitored for FHV-1 shedding, and evaluated for FHV-1 specific humoral and cell-mediated immune responses and fecal microbiome stability. Fecal microbial diversity was maintained throughout the study in cats supplemented with SF68, but decreased in cats fed the placebo, indicating a more stable microbiome in cats fed SF68. While clinical results varied among individual cats, the overall findings suggest that administration of the probiotic lessened morbidity associated with chronic FHV-1 infection in some cats. Additional study is warranted to determine efficacy in a clinical setting.