Determination of hydration status in feedlot cattle treated for respiratory disease and associations with treatment outcome

Feedlot cattle are evaluated visually for signs of disease and to determine subsequent treatment. Hydration status is difficult to measure in feedlot cat­tle, and reference ranges are often based on other cattle pro­duction systems. The objective of this study was to determine the association of clinical markers of hydration at the time of treatment with packed cell volume (PCV) as an indicator of hydration status and treatment outcomes. Cattle treated for respiratory disease (n = 107) were examined to determine eye globe recession, skin tent, mucous membrane quality, capil­lary refill time, rectal temperature and weight. Dehydration was defined as a PCV greater than 46% (n = 9). Animals were followed for 90 days post-enrollment to determine outcomes. Treatment failure was defined as a retreatment for any reason or death due to any cause. Final outcome (died or survived) was also evaluated. Associations between predictor variables and these 3 outcomes (dehydration, treatment failure, final outcome) were determined in 3 generalized linear mixed mod­els. There were no significant associations between predic­tors and dehydration. Weight less than 700 lbs (317 kgs). was associated with an increased treatment failure probability, and abnormal mucous membrane quality was associated with a higher probability of death within the 90 days. This study shows that common markers of hydration status may not be useful in determining dehydration in feedlot cattle. However, weight and mucous membrane quality could be useful indi­cators of outcome. A larger sample size with a more diverse cattle population is needed to validate these results.