2018 ACVIM Forum Research Abstract Program: Seattle, Washington, June 14 - 15, 2018

Important factors associated with increasing within-herd BLV prevalence include a history of prior diagnosis of clinical BLV and history of purchasing cows of unknown BLV status. In this study, there was no significant association of any previously established risk factors with increasing within-herd prevalence of BLV infection. The purpose of this prospective case-control study was to describe bacterial communities in the nasopharynx (NP) of preweaned dairy calves with and without ultrasonographic lung lesions. Additional objectives included evaluating the effects of previous antibiotic therapy and age on the NP microbiota composition. A total of 257 Holstein heifer calves were enrolled into a separate study investigating the genomics of resistance to bovine respiratory disease (BRD) over a 4-week follow up period. Calves were examined twice using thoracic ultrasound and clinical respiratory score (early exam: 4 weeks old; late exam: 7 weeks old). From this population, case and age-matched controls were selected to undergo deep NP swabbing for the current study. Cases were defined by the presence of significant ultrasonographic lung lesions (≥ 1 lobe completely consolidated). Controls were defined by the lack of these lesions.