Investigating factors affecting the body temperature of dogs competing in cross country (canicross) races in the UK

Abstract

Increasing numbers of people are running with their dogs, particularly in harness through the sport canicross. Whilst canicross races are typically held in the winter months, some human centred events are encouraging running with dogs in summer months, potentially putting dogs at risk of heat related injuries, including heatstroke. The aim of this project was to investigate the effects of ambient conditions and running speed on post-race temperature of canicross dogs in the UK, and investigate the potential risk of heatstroke to canicross racing dogs. The effects of canine characteristics (e.g. gender, coat colour) were explored in order to identify factors that could increase the risk of exercise-induced hyperthermia (defined as body temperature exceeding the upper normal limit of 38.8°C).108 dogs were recruited from 10 race days, where ambient conditions ranged from - 5 to 11°C measured as universal thermal comfort index (UTCI). 281 post race tympanic membrane temperatures were recorded, ranging from 37.0-42.5°C. There was a weak correlation between speed and post-race temperature (r = 0.269, P < 0.001). Whilst no correlation between any single environmental factor or UTCI and post-race temperature was found, the proportion of dogs developing exercise-induced hyperthermia during the race increased with UTCI (r = 0.688, P = 0.028). Male dogs (χ(1) = 18.286, P < 0.001), and dark coated dogs (χ(2) = 8.234, P = 0.014), were significantly more likely to finish the race with a temperature exceeding 40.6°C. Prolonged elevati°n of body temperature above this temperature is likely to cause heatstroke. At every race dogs exceeded this critical temperature, with 10.7% (n = 30) of the overall study population exceeding this temperature throughout the study period. The results suggest male dogs, dark coloured dogs, and increased speed of running all increase the risk of heatstroke in racing canicross dogs. Further research is required to investigate the impact of environmental conditions on post-race cooling, to better understand safe running conditions for dogs.

Risk factors for exertional heat illness in Thoroughbred racehorses in flat races in Japan (2005–2016)

“…Dark‐coloured hair coat absorbs more solar radiation and stores heat than white‐coloured hair coat in cows . Further, body temperature of dogs with dark‐coloured hair coat is higher than that of those with light‐coloured hair coat after races . Our results were not consistent with these previous reports.…”

The effect of light vs dark coat color on thermal status in Labrador Retriever dogs

“…The techniques utilized to assess temperature, panting and water consumption are non-technical, readily available methods for canine handlers or owners to assess thermal status of dogs in the field, and thus are important to prevention of heat related injury. These data provide critical evidence to dispute the theory that dark coat color is a risk factor for thermal stress which is reported across several forums including veterinary textbooks and previously published articles [1–4]. In this experiment, dark and light-colored dogs exposed to the same environment showed a similar heat gain and loss (mean peak rectal 40.31±0.37 °C and mean peak GI temperatures 40.65±0.37 °C respectively).…”

“…Darker coat color has been suggested as a potential risk factor for heat injury in dogs in several publications [1–4] However, little evidence is available to support this theory, and a majority of these claims appear in the introduction or discussion sections of publications, or in review articles, with no supporting data. One study in Greyhounds reported higher rectal temperatures in darker colored dogs following exercise but utilized greater numbers of males in the darker coat participant group.…”

Changes in Pulse Rate, Respiratory Rate and Rectal Temperature in Working Dogs before and after Three Different Field Trials

“…Another recent study did not find any direct correlation between ambient conditions and the post-race body temperature of dogs competing in canicross races. However, their results suggested that male dogs, dark coateddogs, and increased speed of running could represent a risk of heatstroke [16]. Greyhounds following even short periods of strenuous exercise commonly exhibit cramps and muscular fatigue [17].…”