Surveillance of heat-related illness in small animals presenting to veterinary practices in the UK between 2013-2018.

Abstract

Background: Heat-related illness (HRI) can affect all companion animals and is likely to become more common as global temperatures rise. The misconception that HRI is primarily a result of dogs being trapped in hot cars, highlights a lack of awareness of HRI risk factors within the UK companion animal population. Aim: This project aimed to review all species of small animal presentations of HRI to UK veterinary practices participating in the Small Animal Veterinary Surveillance Network (SAVSNET), describe the inciting triggers and seasonality of HRI events, and review the clinical grade of canine patients presenting with HRI. Methods: Electronic consultation records were submitted by volunteer veterinary practices across the UK to SAVSNET. Cases were defined as animals presented for consultation with strong evidence of current, or recent heat induced illness during the study period (2013–2018). Results: The HRI cases included 146 dogs, 16 cats, 8 guinea pigs, 3 rabbits and 1 ferret. Of the 118 HRI cases with a recorded trigger, exercise was the primary trigger for dogs presenting (73.5%); 7 (6.9%) canine HRI events followed vehicular confinement. Environmental HRI was recorded as a trigger for the remaining dogs (19.6%), and for all cats, guinea pigs, rabbits and the ferret. Brachycephalic breeds comprised 21.2% of canine HRI cases, and all rabbits were brachycephalic breeds. Dogs with HRI were presented between April and October, with 42.5% during July, typically the UK’s hottest month of the year. Cats with HRI were presented between May and September, with 75.0% during June and July. The smaller companion species—ferrets, rabbits and guinea pigs—were presented during the UK’s summer months June to August. Conclusion: This study highlights the risk of HRI to all pet animals during the UK’s warmer summer months (June to August). The findings support previous claims that exercise is the most common trigger of HRI in dogs, while environmental HRI (a hot ambient temperature) accounted for all HRI events in cats, rabbits, guinea pigs, and ferrets. Both brachycephalic dogs and rabbits were overrepresented, adding further evidence that owners of these animals should be particularly vigilant for HRI during hot weather.

Risk Factors for Severe and Fatal Heat-Related Illness in UK Dogs—A VetCompass Study

“…Previous studies have identified risk factors associated with developing HRI in dogs, including skull shape, bodyweight, age, breed and being overweight [ 24 , 25 , 26 ]. Whilst any dog can develop HRI if exposed to a high enough ambient temperature for long enough, brachycephalic dogs [ 24 , 25 , 27 ], overweight dogs [ 24 , 25 , 34 ], heavier dogs [ 24 ] and dogs aged 2–8 and over 12 years [ 24 ] have greater odds of developing HRI. However, our previous study [ 24 ] explored risk factors for the entire spectrum of severity of HRI presented for veterinary care and did not distinguish between differing risk factors across different severity grades of HRI [ 6 , 24 , 27 ], with only 14% of dogs developing severe disease [ 11 , 27 ] and a survival rate over 95% for dogs with mild/moderate disease [ 11 ].…”

“…Whilst any dog can develop HRI if exposed to a high enough ambient temperature for long enough, brachycephalic dogs [ 24 , 25 , 27 ], overweight dogs [ 24 , 25 , 34 ], heavier dogs [ 24 ] and dogs aged 2–8 and over 12 years [ 24 ] have greater odds of developing HRI. However, our previous study [ 24 ] explored risk factors for the entire spectrum of severity of HRI presented for veterinary care and did not distinguish between differing risk factors across different severity grades of HRI [ 6 , 24 , 27 ], with only 14% of dogs developing severe disease [ 11 , 27 ] and a survival rate over 95% for dogs with mild/moderate disease [ 11 ]. This present study aimed to identify risk factors for HRI progression to severe or fatal disease within those dogs that were recorded with HRI; this information could facilitate more effective triage of affected dogs.…”

“…This has resulted in missing or incomplete data, and some variables (such as location and date of the HRI event) that are imprecise. Diagnosis of HRI is typically based on patient history and presenting clinical signs, and is therefore reliant upon the clinician’s subjective opinion [ 27 ], which could have resulted in misidentification for some of the dogs in this study. As previously noted, some owners may not present their animal for veterinary treatment; thus, the true number of HRI events is likely to be higher than reported here [ 6 , 24 ].…”

“…Previous studies have focused on identifying the intrinsic canine risk factors for HRI in dogs [ 24 , 25 , 26 ] and the most common triggers of HRI in UK dogs [ 6 , 27 ]. However, these studies have not explored combined effects from intrinsic and extrinsic factors such as HRI trigger, ambient condition and geographical location, on HRI severity or fatality.…”

Clinical Evaluation of Exercise-Induced Physiological Changes in Military Working Dogs (MWDs) Resulting from the Use or Non-Use of Cooling Vests during Training in Moderately Hot Environments

“…The most important consequence of hyperthermia, described as an increase in body temperature above the accepted reference range [ 1 ] under conditions of elevated ambient temperature or exercise, is heat-related illness (HRI). The most important clinical signs of HRI are highly limiting for military working dogs (MWDs), as they include respiratory distress, lethargy, collapse, vomiting, diarrhea, hypersalivation, ataxia, seizures, hemorrhage, or coagulation problems, among others [ 2 ]. MWDs, in their different specialties, are confronted, together with their canine handlers, with extremely high temperature conditions, which can have a serious negative impact on the health of the dogs and the safety of the canine handlers.…”