Hagyard Unveils Creation of Novel Salmonella Vaccine

Approximately fifteen years ago, in response to emergent disease conditions within the central Kentucky thoroughbred herd, lead researcher Dr. John Timoney of the Gluck Center - a UK Ag Equine Program and part of the Department of Veterinary Science in the Martin-Gatton College of Agriculture, Food and Environment at the University of Kentucky - worked in conjunction with a team of Hagyard Equine Medical Institute (Hagyard) veterinarians to create Salmonella and Clostridium vaccines. The success of the vaccine was considered a milestone moment for the health and welfare of the thoroughbred population. Recently, that same partnership has come together again to enhance the Salmonella vaccine in hopes of delivering a similar outcome. 

"Over the past several years, veterinarians have observed an increase in horses with Salmonella,” said Dr. Nathan Slovis, DVM, DACVIM, CHT of Hagyard. "We began working to improve the existing vaccine to address the issue.” Dr. Yosra Helmy, an associate professor at the Gluck Equine Research Center, helped identify one of the circulating strains as Salmonella Saintpaul. Whole-genome sequencing revealed that the Salmonella Saintpaul isolates were genetically highly similar and clustered together, indicating they were closely related. The core genomes of the Kentucky strains closely resembled those from outbreaks in Texas and Georgia in 2023 and showed acquisition of antibiotic-resistance genes. This pattern is consistent with clonal expansion, meaning the strains likely originated from a closely related lineage with only minor genetic differences.

"When an infectious disease threat emerges in horses, rapid response is essential,” said Helmy. "Whole-genome sequencing allowed us to identify the circulating Salmonella strain and support a targeted vaccine update. This work shows how Kentucky's equine health community can quickly translate genomic data into practical protection for horses and the Thoroughbred industry.” Today, the Salmonella vaccine has introduced the addition of two new subspecies designed specifically to protect against Salmonella infections. Dr. Nathan Slovis, Dr. Luke Fallon, the Hagyard Laboratory, and other Hagyard veterinarians spearheaded both the enhancement of the vaccine and the assessment of its efficacy.

"This achievement reflects the dedication of leading experts who collaborated to ensure the best outcomes for the horses in our care,” said Dr. Luke Fallon, Medical Director at Hagyard and fifth-generation member of the Hagyard founding family. "The vaccine was developed through extensive pro bono work by the Gluck Equine Research Center and Hagyard veterinarians, with financial support from the Kentucky Thoroughbred Association. We are proud to continue Hagyard's longstanding commitment to equine health and well-being. This milestone marks a highlight in an already remarkable year for Hagyard.”