Enrollment of healthy horses following routine vaccination
Horses were selected based on health status and historical information that they had been on an AAEP-approved vaccine protocol for annual vaccinations. Enrollment criteria included that the owners reported routine annual vaccines had been administered and confirmed no previous adverse vaccine reactions observed. Information was collected via a client questionnaire for all enrolled animals (supplemental information). Horses were determined to be healthy and able to receive routine annual vaccinations following physical examination by a veterinarian (CAB). All horses received the same type of vaccine that were administered by the same veterinarian (CAB). Vaccines administered included a combination against Eastern equine encephalitis (EEE), Western equine encephalitis (WEE), tetanus, West Nile virus (WNV), equine influenza, and equine herpesvirus-1 and -4 (EHV-1/-4)8 and a separate vaccine against rabies.9 All vaccines were administered intramuscularly following label instructions and site of administration was recorded in individual medical records.
Sixty-five healthy horses were enrolled in the study. Horses were either client-owned with client consent or part of the Kansas State University College of Veterinary Medicine (KSU-CVM) teaching herd horses. A convenience sample of client-owned horses and all KSU-CVM teaching herd horses that were due for their annual booster vaccinations during the months of March through July were enrolled into the study. Healthy horses were comprised of Quarter horses (n=39), Thoroughbreds (n=9), Warmbloods (n=5), Appaloosas (n=3), Paints (n=3), Morgan (n=1), Miniature (n=1), Mustang (n=1), Draft (n=1), Haflinger (n=1), and a Tennessee Walking Horse (n=1). All horses were between 3 and 32 years of age. Thirty-three were mares, 31 were geldings and 1 was a stallion.
All 65 healthy horses had blood samples obtained on days 0, 14, 30, 90 and 180 after vaccination. Nineteen of the 65 horses also had blood samples obtained on day 270 after vaccination. Twenty-one of the 65 horses also had blood samples obtained on day 365 after vaccination. Eight of the 65 horses had blood samples collected at both 270 and 365 days after vaccination in addition to the 0, 14, 30, 90, and 180 day time points.
In an effort to determine if there was an age-associated response to BSA-specific IgE expression following vaccination, horses were grouped by age. Subject grouping included horses as young adult (3-9 years), adult (10-14 years), middle aged (15-19 years) and geriatric (20-32 years) as detailed in Table 1.