Table 1

Descriptions of study groups

GroupNo. of horses in groupAge range (yrs)BreedsTime since last known EHV-1 exposureTime (median) since last EHV-1 vaccination
Unvaccinated66–9 (median, 7)1 thoroughbred, 5 draft horse/Arabian crossesNAaNA
Vaccinated204–16 (median, 6)7 thoroughbreds, 5 ponies, 7 unknownNA9–10 mos (10 mos)
Vacc/outbreak187–23 (median, 16)12 thoroughbreds, 6 ponies, 1 standardbred5 yrs2–10 mos (10 mos)
  • a NA, not applicable.