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Type: Theses
Title: Heat stress in racing Greyhounds
Author: McNicholl, Jane Eleanor
Issue Date: 2016
School/Discipline: School of Animal and Veterinary Sciences
Abstract: 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 <33°C the air conditioning system maintained internal trailer temperature below 26°C. Between ambient temperatures 33-37°C, although the internal temperature in the air conditioned trailer rose above 26°C, dogs were able to maintain normal body temperature. Following journeys of approximately 50 minutes in a trailer without air conditioning, mean dog rectal temperature increased by 0.5°C ± 0.2. Results of these studies have identified a number of factors which may increase the risk of greyhounds developing a potentially hazardous level of hyperthermia after exercise. Following racing in external environmental temperatures ≥38°C, 39% of greyhounds developed rectal temperatures ≥ 41.5°C. Large, dark coloured greyhounds are at greater risk of developing hyperthermia. Conditions within kennel houses and transport vehicles may influence dog body temperature as a kennel house temperature ≥ 27°C and transport in temperatures ≥32°C are both associated with an increase in body temperature. These findings will be important in the development of evidence-based guidelines to protect the welfare of greyhounds racing in hot conditions in Australia and other countries.
Advisor: Howarth, Gordon Stanley
Hazel, Susan Jane
Dissertation Note: Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 2016.
Keywords: heat stress
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at:
DOI: 10.4225/55/58dc9291b2327
Appears in Collections:Research Theses

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