Appendix II.

Definitions of groups, explanatory variables and outcome variables explored in analysis

Enrollment parameters
Enrollment groups	Arrival: Cattle designated as arrival fever cases or arrival controls.
	Post-arrival: Cattle designated as post-arrival fever cases, post-arrival no fever cases, or post-arrival controls.
Animal health and production outcomes
Subsequent treatment-ANY	Animals treated for any disease (including BRD) post-enrollment.
Subsequent treatment-BRD	Animals treated for bovine respiratory disease (BRD) post-enrollment.
Chronicity	Animals that were treated 3 times after arrival for the same disease, or animals designated as unable to return to their pens due to sickness by animal health personnel.
Wastage	Animals that developed chronic disease post-enrollment but did not die during the study.
Mortality	Animals that died during the study but were not sacrificed as part of the study design.
ADG to last ultrasound	Average daily gain: weight difference (kg) from enrollment to last ultrasound date divided by number of days for the same time frame (average 26 d, range 23–49 d post-enrollment).
ADG to final rehandling	Average daily gain: weight difference (kg) from enrollment to last feedlot management date (last date weighed) divided by number of days for the same time frame (average 28 d, range 112–140 d post-enrollment).
Ultrasonography lung lesion explanatory variables
Lesion at enrollment	Whether or not a lung lesion was identified using thoracic ultrasonography at the time of enrollment.
Lesion at 2 wk	Whether or not a lesion was identified using thoracic ultrasonography 2 wk post-enrollment.
Lesion at 4 wk	Whether or not a lesion was identified using thoracic ultrasonography 4 wk post-enrollment.
Lesion at 6 wk	Whether or not a lesion was identified using thoracic ultrasonography 6 wk post-enrollment.
Lesion at enrollment was an outcome in some models and an explanatory variable in other models.