Heat stress in racing Greyhounds

Heat related illness has been recorded in dogs undertaking strenuous exercise in high temperatures. In South Australia, summertime daily maximum temperatures may reach 50°C. This study aimed to determine if a safe maximum ambient temperature for racing in greyhounds can be established and if particular environmental or phenotypic factors increase the risk of greyhounds developing hyperthermia. A preliminary study compared four temperature recording devices to determine their suitability for use in a racing environment. Digital rectal thermometry was the most reliable and convenient method of recording greyhounds’ body temperature. An observational study was then undertaken at racetracks in South Australia, during which, environmental temperature and relative humidity were recorded and greyhounds’ body temperatures measured on arrival, pre- and post-race. A mean increase of 2.1 ± 0.4 °C in greyhounds’ (n=239) post-race rectal temperature was recorded. No association was found between environmental temperatures and greyhounds’ temperatures on arrival or pre-race. However, post-racing there was a small but significant relationship between shade temperature and both rectal temperature (r² = 0.023, P = 0.027) and the increase in rectal temperature (r² = 0.033, P = 0.007). No association between environmental relative humidity and body temperature was detected. The influence of sex, bodyweight and coat colour on body temperature increases were investigated. There was a small but significant relationship (r² = 0.04, P = 0.009) between bodyweight and post-exercise rectal temperature. Greyhounds of dark colours developed higher temperatures than light coloured greyhounds (P <0.05). Animal housing at racetracks was examined and temperature and relative humidity levels in enclosed environments were recorded using data loggers and ibuttons. A significant relationship was found between kennel house temperatures and body temperature changes of greyhounds during racing (r² = 0.03, P = 0.009). Temperature and relative humidity levels in dog transport vehicles were monitored with ibuttons when vehicles were stationary and moving in both laden and un-laden states. The effects of an air conditioning system on conditions within a vehicle were measured and responses of dog body temperatures to transport were assessed. In ambient temperatures