Attenuation of the Integrated Cortisol Response Following Administration of Oral Firocoxib in Preweaned Calves Prior to Cautery Disbudding

Abstract Text:

Perioperative analgesic effects of oral firocoxib following cautery disbudding were investigated in preweaned calves. Twenty Holstein calves (55.2±5.8 kg) approximately 35 days old were orally administered firocoxib, a non-steroidal anti-inflammatory prostaglandin blocker, using a dose of 0.5 mg/kg (n=10) or whey protein placebo (n=10) in a randomized clinical trial. All animals received a cornual nerve block using a local anesthetic prior to disbudding. Pain biomarkers including ocular temperature determined by infrared thermography, pressure algometry measuring mechanical nociception threshold, and heart rate were evaluated following cautery disbudding at 2, 4, 7, 8, and 24 hrs. Blood samples were collected over 96 hours and analyzed for plasma cortisol and substance P concentrations by radioimmune assay. Additionally, ex-vivo prostaglandin E₂ (PGE₂) concentrations were determined over the same 96 hour study period using an enzyme immunoassay. Data were analyzed using a linear mixed effects model with repeated measures. An attenuation of the integrated cortisol response (mean±LSM) as calculated as area under the effect curve was greater in placebo treated calves (1611.1±249 nmol.h/L vs. 1114.2±181 nmol.h/L) (p=0.058). A significant decrease in cortisol concentrations (mean±LSM) was observed in firocoxib treated animals at approximately 48 hrs after disbudding (11.3±1.9 nmol/L vs. 22.8±2.8 nmol/L) (p=0.0013). Additionally, a significant inhibition (p<0.01) of ex-vivo PGE₂ concentration was observed from 12 to 48 hrs following disbudding in calves treated with firocoxib. These data support the potential for firocoxib to be used to provide analgesia after cautery disbudding in calves; however, further investigation of its perioperative analgesic effects is warranted. 

Keywords: Disbudding, welfare, NSAIDs