Abstract
Objective—To identify factors associated with an increased likelihood that horses would have a serum Streptococcus equi SeM-specific antibody titer ≥ 1:1,600.
Design—Cross-sectional study.
Animals—188 healthy client-owned horses.
Procedures—A single serum sample from each horse was tested for SeM-specific antibody titer with an ELISA. Multivariate logistic regression was used to identify factors associated with having a titer ≥ 1:1,600.
Results—Age, breed, and vaccination status were significantly associated with the likelihood of having a titer ≥ 1:1,600. The odds of having a titer ≥ 1:1,600 increased by a factor of 1.07 with each 1-year increase in age. Quarter Horses and horses of other breeds were 4.08 times as likely as were Thoroughbreds and warmbloods to have a titer this high. Horses that had previously received an intranasal S equi vaccine were 4.7 times as likely as were horses without any history of vaccination to have a titer this high.
Conclusions and Clinical Relevance—Results indicated that older horses, horses other than Thoroughbreds and warmbloods, and horses that had been vaccinated with an attenuated-live intranasal S equi vaccine between 1 and 3 years previously had an increased likelihood of having a serum SeM-specific antibody titer ≥ 1:1,600.
