A Closer Look At: One Company’s Quest For Smarter, Better Use Of Antibiotics For Equine Respiratory Disease

In this series, we ask some of the equine health questions you’ve wondered about but were too afraid to ask. Today, Dr. Duane E. Chappell, associate director of equine professional services and pharmacovigilance at Merck Animal Health, tells us a little more about the company’s biosurveillance program.

What prompted Merck to launch the upper respiratory biosurveillance program? 

Dr. Duane Chappell – Merck Animal Health launched this value-add service to customers for the identification of upper respiratory pathogens. The following four objectives have been the pillars of the Equine Respiratory Biosurveillance Program since its 2008 inception:

  1. To provide a diagnostic tool to assist with accurate and timely diagnosis of an upper respiratory pathogen
  2. Provide the horse industry with a better understanding of the prevalence and epidemiology of respiratory pathogens
  3. To identify and monitor the current circulating strains of the major equine respiratory pathogens
  4. A means to evaluate the efficacy of current vaccination protocols

The program has collected more than 10,000 samples since it began in 2008.

How easy is it for equine veterinarians in remote places to get lab results when testing a horse with respiratory illness?

Ideally, a clinic will have a designated point person to coordinate these activities. Whether in a remote location or a heavily populated area, that person should have a plan in place that identifies which sample to collect (nasal swab and purple top blood tube). Proper sample handling from time of collection, completion of the correct submission form and appropriate shipping label will all be essential to receive timely results. Overnight delivery services transport samples to the University of California, Davis, PCR Laboratory (the exclusive laboratory partner of the Merck Animal Health Equine Respiratory Biosurveillance Program), which offers laboratory results within 24 hours of sample arrival. Results are reported by email or fax allowing the attending veterinarian to make very timely decisions for treatment, isolation and biosecurity.

How does a horse qualify for this program?

Once a clinic is enrolled in this value-add program, patient selection begins with a febrile horse (rectal temperature > 101.5o F) and the presence of one or more of the following clinical signs: nasal discharge, cough, depression/lethargy, and/or central nervous system signs like ataxia. This criterion plays a significant role in identifying horses early in the course of disease, which improves the opportunity to identify a causative infectious pathogen.

What pathogens are commonly reported in the laboratory results?

The panel includes equine herpesvirus-1 & 4, equine influenza virus, Streptococcus equi subsp. equi, and equine rhinitis A & B virus.

I know we now have a few more resources to compile information about certain types of infectious diseases than we did a few years ago; are there still gaps in veterinarians’ ability to monitor regional outbreaks?

The Equine Disease Communication Center (EDCC) is an industry-driven effort to centralize infectious disease reporting and bring horse industry awareness of regional outbreaks. Through disease reporting by state veterinarians, state animal health officials and attending veterinarians, disease outbreak alerts are created and provide real-time information on the website. Subscribers to this service can receive an alert as new postings are made. In addition, Merck Animal Health reports findings from the Equine Respiratory Biosurveillance Program on a bi-weekly basis through the EDCC.

Are there applications for this type of testing beyond diagnosing an actively sick horse?

Identifying the cause of illness has many positive outcomes in the management of respiratory disease for the individual involved as well as the herd. Causative pathogen identification can help in the decision process of when (and when not) to use antibiotics, how to institute and monitor isolation procedures and broader biosecurity measures for the herd as well as the competition and/or sale facility grounds. Vaccination protocols can be reviewed considering the laboratory results to make critical assessments in effectiveness of current vaccination practices. Decisions regarding frequency and timing of administration, as well as product selection, can then be made.

Biosurveillance is an active engagement in disease identification and monitoring, biosecurity management and analysis of vaccination protocols. In the absence of identifying pathogens, appropriate responses cannot be made to protect the horse population.

Dr. Duane E. Chappell is Associate Director of Equine Professional Services and Pharmacovigilance for Merck Animal Health.

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