393 Young Scholar Award Talk: Investigation of Pain and Analgesic Strategies in Cattle Undergoing Painful Husbandry Procedures and Disease Conditions
Authors: Martin Miriam S , Kleinhenz Michael D , White Brad J , Viscardi Abbie , Edwards-Callaway Lily N , Engle Terry E , Johnson Blaine , Montgomery Shawnee R , Curtis Andrew K , Weeder Mikaela , Lou Maria E , Blasi Dale A , Almes Kelli M , Amachawadi Raghavendra G , Salih Harith , Miesner Matt D , Cull Charley A , Seagren Jon E , Lechtenberg Kelly F , Baysinger Angela , Nickell Jason , Guimareas Octavio , Schafer David , Coetzee Johann F 
Published: September 2022

Abstract
Cattle are stoic by nature and have long been subject to evolutionary pressure to mask pain to avoid becoming prey. Quantifying pain via biomarkers allows researchers to capture changes that are not easily detected by the human eye. Negative public perception of routine husbandry practices such as dehorning and castration is growing, increasing the need for the development of practices to relieve pain and suffering in cattle. The objective was to quantify pain associated with induced bacterial pneumonia, scoop and hot-iron dehorning, surgical castration, and hot-iron branding, and to investigate analgesic effectiveness. Calves were experimentally inoculated with Mannheimia haemolytica, scoop or cautery dehorned, surgically castrated, or hot-iron branded. Outcome variables were collected at baseline and following husbandry procedures and included serum cortisol; infrared thermography (IRT); mechanical nociceptive threshold (MNT); substance P; kinematic gait analysis; a visual analog scale; chute defense and behavior scoring; clinical illness score; computerized lung score; average activity and rumination; prostaglandin E2 metabolite; plasma serum amyloid A and rectal temperature. Responses were analyzed using repeated measures with calf nested in treatment designated as a random effect, and treatment, time, and their interaction designated as fixed effects. A combination of reduced activity levels, decreased force on calves’ right front limb, and increased visual analog scale pain scores all support that bacterial pneumonia in cattle is painful (P ≤ 0.01). Differences in right front force were observed in calves challenged with M. haemolytica and treated with flunixin transdermal (96.5 kg) and those given a placebo (85.5 kg), indicating that flunixin transdermal may attenuate specific pain biomarkers in cattle with respiratory disease (P &lt; 0.01). Administration of a bupivacaine liposome suspension block at the time of dehorning and castration was as effective at controlling pain as a multi-modal approach of lidocaine and meloxicam (as evidenced by treatment differences in MNT, cortisol and gait analysis (P ≤ 0.04)). Oral meloxicam administration at branding reduced IRT differences from the branding and control site and reduced lying bouts (P &lt; 0.01). Breed and sex effects were observed across a wide range of biomarkers and should be investigated in future pain studies. The need for long-acting analgesic options for cattle that demonstrate pain alleviation across multiple biomarkers is apparent and would be beneficial to alleviating pain from routine husbandry procedures like dehorning, castration, and branding, as well as painful disease conditions such as bovine respiratory disease.