Hair cortisol as a marker of hypothalamic-pituitary-adrenal axis activation in friesian dairy cows clinically or physiologically compromised.

This studywasdesignedtoassesshypothalamic-pituitary-adrenal(HPA)axisactivation in lactatingcowsclinicallyorphysiologicallycompromised.Cortisolwasmeasuredinthe hairof475multiparouscowsofItalianFriesianbreed.Thecowswereclassifiedinto GroupsA(n1⁄4218) andB(n1⁄4257). GroupAincludedcowsclinicallycompromisedthat had recentlysufferedadisease(e.g.metritis,laminitis,mastitis)orphysiologically compromisedthatcalved1monthpriortohairsampling.GroupBwereclinicallynormal lactatingcowsatleast60daysaftercalvingwithsomaticcellcountsoflessthan200,000 cells/mlinmilk.AnimalsinGroupAshowedhigherhaircortisollevelsthanthosein GroupB(Po0.01).Significantpositivecorrelation(rpb1⁄4þ0.352, Po0.001) was detectedbetweenhaircortisolandcowsclinicallyorphysiologicallycompromised. The areaunderthereceiveroperatingcharacteristiccurvewas0.701(SE0.024)anda cut-offvalueof4.17pg/mgwasfoundtodiscriminatebetweengroupsAandBwitha sensitivityof62.4%andspecificityof69.3%.Thehaircortisoltestemergedasusefulto determineHPAactivationandtoenhancecurrentunderstandingontheinvolvementof thisaxisinclinicallyorphysiologicallycompromisedcows.