Texas Equine Veterinary Association

Page 29 | The Remuda | SPRING 2024 EDITION FIGURE 2: Disease Incidence January-December 2023 of all ages, genders and breeds presenting with common signs of upper respiratory disease. Submitted samples must meet the criteria of a fever (≥101.5°F) and the presence of at least one of the following clinical signs of upper respiratory disease: nasal discharge, cough, lethargy and/or central nervous system signs. What have we learned? The Biosurveillance Program has played a crucial role in enhancing our understanding of equine infectious upper respiratory disease. The data collected over the past 16 years continues to identify equine herpesvirus type-4 (EHV-4) and equine influenza (EIV) as the most widespread upper respiratory pathogens among horses, contributing to a significant portion of positive test results. However, the program has been tracking an uptick in S. equi the past two years, and it was the most prevalent pathogen tested from January 1 to December 31, 2023 (See Figure 2). One of the hallmarks of the Biosurveillance Program is the ability to monitor what time of year pathogens are most prevalent. This continues to inform vaccination recommendations and protocols to help veterinarians protect horses from infectious disease outbreaks. However, findings from the program support that vaccination alone does not provide complete disease protection. Particularly for highly contagious diseases like equine herpesvirus, influenza and S. equi, sound biosecurity practices provide a broader net of disease protection. Impact in the equine health industry During an acute outbreak of infectious upper respiratory disease, an accurate and timely diagnosis is critical to ensure proper treatment of affected horses. It is also extremely important in providing guidance regarding vaccination, management and biosecurity. The Biosurveillance Program not only increases awareness of respiratory pathogens in the veterinary community, but also gives veterinarians access to accurate pathogen identification, quick diagnoses and insights into local disease incidence to help them manage potential disease outbreaks. The program has delivered nearly two decades of important ongoing surveillance data on infectious upper respiratory disease in horses. During that time, one of its most significant contributions is the identification and isolation of Florida '13. This highly pathogenic strain of influenza is considered the most current, clinically significant strain and is only available in Merck Animal Health's PRESTIGE® vaccines. Several scientific peer-reviewed publications and presentations have been generated from this dataset to share information to the broader equine community. Through biannual publications to participating veterinarians, data is used to bring new information to the forefront and provide timely updates to share with horse owners. Learn more about the Merck Animal Health Equine Biosurveillance Program by contacting your sales representative or visiting www.merck-animal- health-usa.com/species/equine. References 1 Voluntary Surveillance Program for Equine Influenza Virus in the United States during 2008–2021. Chappell, D.E., Barnett, D.C.; James, K.; Craig, B.; Bain, F.; Gaughan, E.; Schneider, C.; Vaala, W.; Barnum, S.M.; Pusterla, N. Pathogens 2023, 12, 192. 2 Merck Animal Health and University of California, Davis (Nicola Pusterla). Infectious Upper Respiratory Disease Surveillance Program. Ongoing research 2008–present.

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