Evaluation of the usefulness of a PCR assay performed at a clinical laboratory for the diagnosis of respiratory disease induced by equine herpesvirus type 1 in the field.

The research discusses the effectiveness of a PCR assay performed at a clinical laboratory as a diagnostic tool for respiratory diseases caused by equine herpesvirus type 1 (EHV-1). The study indicates that the PCR assay can assist in making an early diagnosis of EHV-1 infection but should not be relied upon as the sole diagnostic method.

Study Overview

• The study was conducted at the Racehorse Clinic of the Ritto Training Center of the Japan Racing Association between December 2007 and March 2008.
• Horses were regularly tested for EHV-1 infection using a PCR (Polymerase Chain Reaction) assay. The turnaround time for the assay was roughly 6 hours.
• The objective of the research was to evaluate the effectiveness of the PCR assay as a diagnosing tool for respiratory diseases induced by EHV-1.

Findings

• The PCR assay was performed successfully without contamination throughout the study.
• For horses that had seroconverted (i.e., developed specific antibodies against the virus), the PCR detection rates were found to be 22.2% for nasal swabs and 33.3% for blood samples.
• Interestingly, the PCR assay detected EHV-1 DNA in horses that had not seroconverted, although the detection rate was low.

Implications

• These findings suggest that the PCR assay can be a valuable tool for early diagnosis of EHV-1 infection in horses.
• However, due to the low detection rate among horses without seroconversion and the variability in detection rates between sample types, the PCR assay should not be used as the only method for diagnosis.
• Therefore, the research recommends the use of the PCR assay as an adjunct method—i.e., in combination with other diagnostic tools—for the diagnosis of EHV-1 induced respiratory diseases in horses.