Serum cortisol associated with the severity of foot pathology and locomotion score in dairy cows in pastoral systems

Abstract

This study evaluated the stress response – in terms of cortisol secretion- of podal pathologies of different severity and it association with locomotion score in acute (Exp. 1, 29 lame cows and 44 healthy cows) and chronic outbreaks (Exp. 2, 53 lame cows and 44 healthy cows) in lactating Holstein cows. Podal pathologies were classified in painful and mild according to the tissues that were affected, grade of foot wear and inflammation and infection. Podal discomfort of chronic cases were evaluated by the locomotion score (1= healthy, 5=severe lameness). Cortisol was determined by radioimmunoassay. In the acute outbreak, cows with severe lameness presented greater plasma cortisol concentrations than cows with mild lameness and healthy cows, which did not differ. Foot wear was t most severe pathology with greatest cortisol levels. In chronic cases, no differences were found among lame and healthy cows, although the latter presented a reduced cortisol: creatinine ratio. In this study, cortisol –plasmatic levels and/or its ratio with creatinine in urine- was a good stress index for podal pathologies when these were classified according to degree of severity considering the type of lesion and tisular affection.