Welfare of horses transported to slaughter in Canada and Iceland: Assessment of welfare issues and associated risk factors

Abstract

The welfare of horses transported for slaughter is a growing concern in several countries, including Canada, Iceland and the United States of America (USA). Slaughter of horses involves transportation of horses to a regulated facility and slaughter procedures such as lairage and stunning. The main objective of this study was to identify welfare issues and associated risk factors, particularly those associated with transportation. A welfare assessment protocol was developed to identify pertinent welfare issues, such as injuries, dehydration and fitness for transportation. Prevalence of horses with injuries, a pre-existing clinical condition, a body condition score of less than 3 (on a scale of 5) and those in a non-ambulatory state were calculated. Skin temperature, respiration rate, blood lactate concentration, blood glucose concentration, plasma osmolality, plasma total protein concentration and packed cell volume were also measured. Welfare assessment of horses in Iceland was undertaken before and after transportation to the slaughter plant and at slaughter. Forty six journeys lasting up to 3 hours were studied. Welfare issues identified were the prevalence of bruising and dehydration. Adults were more prone to bruising and dehydration than foals. Some horses showed signs of consciousness after stunning (1.6%) indicating ineffective stunning. In Canada, a prospective study observed 150 truckloads of horses after transportation to a Canadian slaughter plant. Associations between risk factors and welfare outcomes were evaluated using linear regression models. Welfare issues identified were prevalence of injuries, pre-existing clinical conditions, low body condition scores, and the presence of some non-ambulatory horses. There was a significant association between journey duration and the number of horses per truckload with injuries. Signs of dehydration were identified and were associated with journey duration and season. Blood lactate concentration at slaughter indicated increased anaerobic metabolic activity, which was affected by season (summer or winter) and lairage duration. A retrospective study was performed by collating data from all shipper certificates obtained from USDA for journeys in 2009 from the USA to equine slaughter plants in Canada. This study identified journey durations range from one hour to 105 hours. Some injuries in horses transported for slaughter were visible at ante-mortem inspection, whereas other injuries, such as bruises were not visible until post-mortem examination. Digital infrared thermography (DT) was evaluated as a potential tool to detect bruising ante-mortem. A preliminary study to evaluate factors affecting skin temperature (as measured by DT) indicated that an outdoor environment significantly affected skin temperature measured on different regions of interest (ROI) compared with an indoor environment. However, thermal symmetry between ROIs was maintained in outdoor conditions. Using these findings, a second study was performed to evaluate the methodology to detect bruising ante-mortem. Sensitivity to detect bruising was low, possibly due to selection of horses that did not spend time in lairage (i.e. there was no equilibrium time for skin temperature to stabilise after transport). In conclusion, in Canada, injuries and dehydration were mainly associated with journey duration, aggressive behaviour between horses and season. In Iceland, injuries and dehydration were mainly associated with age (adult or foal)

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Last time updated on 19/11/2016

This paper was published in IslandScholar.

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