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This project began by exploring risk factors for heat-related illness in UK dogs and has been extended to develop and evaluate a novel clinical grading tool that aims to improve recognition and management of this potentially fatal condition.

Challenge

Heat-related illness (including heatstroke, the most severe form) is a potentially fatal, but often preventable, condition for dogs which is predicted to become more common as global temperatures rise. Understanding the risk factors for heat-related illness is an important step in developing improved mitigation strategies to help protect canine welfare in the face of advancing climate change. In human medicine, improved understanding of the underlying triggers and progression of heat-related illness in clinical patients has helped to develop more targeted educational campaigns to support communities threatened by heat stress risk. The first phase of this VetCompass project funded by Dogs Trust Canine Welfare Grant identified canine demographic risk factors for heat-related illness in UK dogs; these included being overweight, brachycephalic conformation, or aged 2 years or over. The breeds at greatest risk of developing heat-related illness were the Chow Chow, Bulldog and French Bulldog. The most common trigger for heat-related illness in UK dogs was found to be exercise, with almost three quarters of all cases presenting to veterinary practices following some form of canine activity, predominantly walking (67.5%). Other triggers of heat-related illness included being exposed to high environmental heat (12.9% of cases), being confined in a hot vehicle (5.2% of cases), and being confined in a hot building (2.7%) of cases). Most cases of heat-related illness in UK dogs occurred during July, but there were events all year round.

Solution

Traditionally, the human heatstroke criteria have been used to diagnose dogs presenting to veterinary practices with heat-related illness, and body temperature at presentation has been a key diagnostic criterion. The human heatstroke criteria are based on symptoms personally reported by patients, meaning they are of limited use in veterinary patients. The Hot Dogs team have proposed a novel clinical grading tool for heat-related illness in dogs based on VetCompass clinical data, which uses canine specific clinical signs to differentiate between mild, moderate and severe disease. Seeking veterinary treatment when the grade is mild-moderate is associated with an improved survival rate (around 95%), whereas only 43% of dogs that presented with severe disease survived. Improving the recognition of early grade heat-related illness is therefore an important strategy for protecting canine health and welfare in the face of rising global temperatures and climate change. Identifying the canine risk factors and primary triggers of heat-related illness was the first priority for this research project, aiming to improve awareness of the condition amongst both pet owners and veterinary professionals. Thanks to an additional Dogs Trust Canine Welfare Grant the Hot Dogs project is now commencing a second phase of research which aims to evaluate the novel VetCompass clinical grading tool for heat-related illness in dogs for use in emergency veterinary practice. Dogs presented for veterinary care in the mild-moderate stages of the condition have reduced mortality and morbidity compared to dogs presenting with severe disease. Therefore, it is hoped this novel grading tool will assist veterinary professionals in the triage of these emergency cases to support evidence-based decision making and improve patient outcomes.

Impact

The Hot Dogs project has identified that exercise, and not vehicle confinement, is the most common reason dogs present for veterinary treatment of heat-related illness in the UK. This finding has prompted an update to the annual “Dogs Die in Hot Cars” campaign, adding the “Dogs Die on Hot Walks” message to support owners in protecting canine health during hot weather. Organisations including the British Veterinary Association and RSPCA have changed their annual canine heat-related illness social media campaigns to include the dangers of exercising dogs in hot weather in response to this research project. The VetCompass clinical grading tool for heat-related illness in dogs was presented to the British Small Animal Veterinary Association’s annual Congress in 2021, and then featured in the internal medicine clinical education programme in 2022 as part of a talk focused on approaching and managing hot patients. The next stage towards enhanced impact from this work is to trial the VetCompass clinical grading tool in a nationwide group of veterinary emergency-care clinics to explore the utility in a real-world setting.

Publications