Prevalence of equine herpesvirus-1 infection among Thoroughbreds residing on a farm on which the virus was endemic.
OBJECTIVE
To determine the incidence of equine herpesvirus-1 (EHV-1) infection among Thoroughbreds residing on a farm on which the virus was known to be endemic.


METHODS
Prospective cohort study.


METHODS
10 nonpregnant mares, 8 stallions, 16 weanlings, 11 racehorses, and 30 pregnant mares and their foals born during the 2006 foaling season.


METHODS
Blood and nasopharygeal swab samples were collected every 3 to 5 weeks for 9 months, and placenta and colostrum samples were collected at foaling. All samples were submitted for testing for EHV-1 DNA with a PCR assay. A type-specific EHV-1 ELISA was used to determine antibody titers in mares and foals at birth, 12 to 24 hours after birth, and every 3 to 5 weeks thereafter.


RESULTS
Results of the PCR assay were positive for only 4 of the 1,330 samples collected (590 blood samples, 590 nasopharyngeal swab samples, 30 placentas, and 30 colostrum samples), with EHV-1 DNA detected in nasal secretions from 3 horses (pregnant mare, stallion, and racehorse) and in the placenta from 1 mare. Seroconversion was detected in 3 of 27 foals during the first month of life.


CONCLUSIONS
Results suggested that there was a low prevalence of EHV-1 infection among this population of Thoroughbreds even though the virus was known to be endemic on the farm and that pregnant mares could become infected without aborting. Analysis of nasopharyngeal swab samples appeared to be more sensitive than analysis of blood samples for detection of EHV-1 DNA.
Brown
James A
JA
Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Mapes
Samantha
S
Ball
Barry A
BA
Hodder
Aaron D J
AD
Liu
Irwin K M
IK
Pusterla
Nicola
N
D000034:Abortion, Veterinary / Q000453:epidemiology; D000818:Animals; D000831:Animals, Newborn; D015331:Cohort Studies; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D006566:Herpesviridae Infections / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary*; D004861:Herpesvirus 1, Equid / Q000302:isolation & purification*; D006734:Horse Diseases / Q000453:epidemiology* / Q000635:transmission; D006736:Horses; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary; D008297:Male; D009305:Nasopharynx / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology / Q000662:veterinary*; D015995:Prevalence; D011446:Prospective Studies
D004279:DNA, Viral