Molecular prevalence of equine herpesvirus type 1 and equine herpesvirus type 4 in thoroughbred and Arabian horse facilities in Türkiye

Equine herpesvirus-1 and -4 are contagious viruses causing respiratory disease and reproductive losses in horses. This study aimed to determine the prevalence of EHV-1 and EHV-4 in eight Turkish stud farms using RT-PCR analysis of nasal secretions, uterine fluids and aborted foal tissues. Deep nasal swabs were collected from 443 horses showing acute-onset fever and/or clinical signs of respiratory disease. Additionally, uterine swabs and tissue samples (lung, liver, spleen, thymus, kidney, heart) were obtained from 152 abortion cases. Among symptomatic horses, EHV-1 DNA was found in 2 cases (0.45%), while EHV-4 DNA was detected in 67 (15.1%). One horse (0.23%) was positive for both viruses. From abortion-related samples, EHV-1 DNA was identified in 2 cases (1.32%), while no EHV-4 DNA was found. In 4,915 asymptomatic horses, 13 (0.26%) carried EHV-4; none were positive for EHV-1. Overall, active infection rates were 0.67% for EHV-1 and 11.26% for EHV-4. The low prevalence observed in this study suggests minimal active circulation of EHV-1 and EHV-4 in this large, semi-enclosed and well-managed equine population maintained under strict biosecurity and extensive vaccination programs. Although these findings do not reflect national or regional prevalence, they provide valuable epidemiological insight into the effectiveness of consistent vaccination, quarantine measures and PCR-based surveillance in limiting herpesvirus circulation. Overall, the results contribute to improved understanding, surveillance and control strategies for equine herpesviruses in Türkiye.

Jockey Club Turkiye
Kastamonu University
Erciyes University