Measuring Response to Pain Mitigation for Ovariectomy in Bos taurus Yearling Beef Heifers
Lauder, Jean 1956-
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Modern society is concerned about the humane treatment of food animals. Pain mitigation is desirable and expected when surgical procedures are performed on cattle. More than a million Bos taurus and Bos indicus female cattle are surgically ovariectomized (spayed) annually in areas where extensive grazing management is practiced around the world, most commonly using the dropped ovary technique (DOT) which accesses the ovaries via a colpotomy (trans-vaginal) approach. This procedure prevents estrus cycling and pregnancy in cull females that will end up fattened for meat production rather than breeding stock. Producers can realize financial benefits, and heifers may experience better welfare when they are not pregnant on arrival at the feedlot. However, no analgesia for bovine ovariectomy has been described in the literature. The purpose of this research was to design an effective pain mitigation protocol for ovariectomy. Analgesic drugs that were easily administered, rapidly effective and did not cause recumbency were essential to minimize stress and enable administration while heifers were in the handling system for ovariectomy. Two experiments were performed, each using an injectable combination of the analgesic drugs butorphanol (0.01 mg/kg), xylazine (0.02 mg/kg) and ketamine (0.04 mg/kg) (BXK) that was administered by intramuscular injection while heifers waited in the chute race and the oral anti-inflammatory meloxicam (1 mg/kg) that was administered in the squeeze chute where ovariectomy was performed. To determine the efficacy of the protocol, behavioural (experiments 1 and 2) and physiological (experiment 2) data were collected. The objectives were to 1) determine the degree of stress and pain that ovariectomy causes in yearling beef heifers, 2) to determine whether BXK administered 5 min prior to ovariectomy could mitigate the procedural and immediate post-operative pain of ovariectomy, 3) to determine whether oral meloxicam administered at the time of ovariectomy could mitigate the post-surgical inflammatory pain of ovariectomy and 4) whether it was possible to administer the drug protocol in a ranch setting without hindering the spaying process. Experiment 1 was a randomized controlled clinical trial with a 2 × 2 factorial design that took place on a cattle ranch using 120 yearling beef heifers (302 ± 27 kg) scheduled for ovariectomy. Heifers were weighed, identified with ear tags and had activity data loggers affixed to a hind limb prior to spaying on d -1. Heifers were spayed on d 0 and randomly allocated to 4 treatment groups: control (no treatment), BXK, meloxicam, or BXK and meloxicam; then observed for the next 5 d. Behavioural data collected included visual analog scale (VAS) scoring and pain-related behaviour recording by observers during ovariectomy, and stride length, gait score, standing/lying behaviour and video recording for feeding duration measurement after ovariectomy. More BXK treated heifers (P = 0.002) walked after leaving the squeeze chute and lay down for a larger percentage of time (P < 0.01) at 4 h after ovariectomy compared to those not treated with BXK, and meloxicam treated heifers stood for a larger percentage of time at 7 h (P = 0.02), 8 h (P = 0.001) and 9 h (P = 0.02) after spaying compared to those not treated with meloxicam. On the day of ovariectomy, groups that had BXK (P = 0.03) and BXK and meloxicam (P = 0.002) had longer feeding event durations compared to controls. On the day after ovariectomy, heifers treated with meloxicam stood for a smaller percentage of the day (P = 0.01) and for shorter periods of time (P = 0.03) compared to heifers not treated with meloxicam. Behavioural measurements provided minimal evidence of pain from ovariectomy and its alleviation. Experiment 2 took place at a research facility using 45 yearling beef heifers (322 ± 27 kg) randomly allocated to 3 treatment groups: PALP (control group palpated but not spayed), SPAY (spayed without analgesia) and BXKM (spayed with analgesia). Continuous data was gathered over 7 d using accelerometers for activity and the GrowSafe System for feeding behaviour. Saliva and blood samples were harvested, rectal temperature was taken, and recording of flight speed, stride length and gait occurred on d -1, d 0 (time of palpation/ spaying), and 1, 2, 4, 24, 48, 96 and 168 h after palpation/spaying. Salivary cortisol concentrations were lower in BXKM heifers than SPAY heifers at 1 h (P = 0.01) and 2 h (P = 0.004) after ovariectomy. Serum haptoglobin concentrations were lower in BXKM heifers than SPAY heifers at 48 h (P = 0.01), 96 h (P < 0.001), and 168 h (P = 0.008) and lower than PALP heifers at 96 h (P < 0.001) after ovariectomy. Serum amyloid A concentrations were higher in BXKM heifers than PALP heifers (P = 0.04) at 1 h after ovariectomy and at 24 h after ovariectomy PALP heifers had lower concentrations than BXKM (P = 0.02) and SPAY (P = 0.05) heifers. Rectal temperatures were greater in BXKM heifers than PALP and SPAY heifers at 1 h (P < 0.001) and 2 h (P = 0.004) after ovariectomy. Results suggest that ovariectomy is acutely stressful and painful, BXK mitigated the procedural and immediate post-surgical pain of ovariectomy and meloxicam reduced the post-surgical inflammation and inflammatory pain for up to 7 days after ovariectomy.
DegreeMaster of Science (M.Sc.)
DepartmentWestern College of Veterinary Medicine
ProgramLarge Animal Clinical Sciences
SupervisorJelinski, Murray D.; Janzen, Eugene D.
CommitteeSchwartzkopf-Genswein, Karen S.; Haley, Derek B.; Waldner, Cheryl L.
Copyright DateSeptember 2018