Study Finds Link Between ERAV and Horse Age

Age appears to be a significant factor in the prevalence of equine rhinitis virus A and B (ERAV and ERBV) in several regions of the United States, according to a recent study results.

Boehringer Ingelheim Vetemedica Inc. (BIVI) conducted the research in collaboration with veterinarians at several leading universities. Rob Keene, DVM, equine technical manager for BIVI, presented the results at the 2012 American College of Veterinary Internal Medicine Forum in New Orleans, La.

"Equine rhinitis viruses have been associated with respiratory disease outbreaks worldwide," Keene said. "ERAV and ERBV infections cause subclinical signs, fever, nasal discharge, coughing, anorexia, pharyngitis (inflammation of the throat), laryngitis, and enlarged submandibular lymph nodes. Over the past decade, serologic evidence of infection has been documented in Canada, Australia, and throughout Europe. However, little recent serologic data exists in horse populations in the United States."

The objective of the study was to determine the seroprevalence of ERAV and ERBV in horses between the ages of one and four years by measuring serum-neutralizing antibodies in diverse geographic regions of the United States. Frozen serum samples were obtained from six veterinary laboratories and shipped to Cornell Animal Health Diagnostic Center for evaluation.

Serum samples from 1,021 horses were evaluated. Forty-four percent (451 horses) had neutralizing antibodies greater than or equal to 1:96 (which was considered significant) to ERAV, while 16% (164 horses) were positive for ERBV. Of the 1,021 horses evaluated, specific ages were available for 554 horses. Seroprevalence for exposure to ERAV appeared to increase with age:

  • Yearlings: 9% (11 of 126)
  • 2-year-olds: 38% (44 of 116)
  • 3-year-olds: 31% (50 of 163)
  • 4-year-olds: 35% (52 of 149)

"Serum neutralization antibodies to ERAV appear to be more common than ERBV in the population studied," Keene concluded. "ERAV and ERBV infections warrant further investigation in horse populations in the United States and determination of their relationship to other concurrent respiratory pathogens in horses."

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