EHV-1 Congenital Infection and Concurrent Actinobacillus equuli Septicemia in a Standardbred Neonatal Foal: Clinical, Diagnostic Findings, and Evaluation of Adrenal Gland Function

Neonatal septicemia is the most common cause of death in neonatal foals. Actinobacillus equuli subsp. equuli is one of the most frequently isolated bacteria in septic foals, which leads to a syndrome colloquially known as “sleepy foal disease.” Congenital equine herpesvirus 1 (EHV-1) infection becomes evident within 14-18 hours after birth and foals often die within 24-72 hours. Previous studies have reported the association between A. equuli subsp. equuli and EHV-1; however, no clinical reports are present in the literature. This report describes the clinical presentation of A. equuli subsp. equuli septicemia secondary to EHV-1 congenital infection in a 6-hour-old foal. The foal developed a relative adrenal insufficiency, confirmed by hormonal concentrations. Adrenal gland ultrasonographic images were obtained, and the findings were coherently correlated with both macroscopic and histological postmortem evaluation.