Plain-English summary
Public campaigns about dogs and heat are almost entirely about cars. This 2020 study of more than 900,000 UK dogs suggests the messaging has been aimed at the wrong risk.
Of 1,259 heat-related illness events identified, exercise was the trigger in 74.2% of them. Confinement in a vehicle accounted for 5.2%. The authors' title says it plainly: dogs don't die just in hot cars.
None of this makes leaving a dog in a car acceptable. What it changes is where an owner's attention should be on a warm day — and the answer, for most dogs, is the walk.
What the study found
Researchers used the VetCompass programme to review de-identified electronic patient records from 905,543 dogs under primary veterinary care in the UK during 2016, identifying 1,259 heat-related illness events across 1,222 dogs.
Exertional heat-related illness was the predominant trigger at 74.2% of events. Environmental heat accounted for 12.9%, and vehicular confinement for 5.2%.
The risk profiles differed by trigger type. Young male dogs had greater odds of exertional heat-related illness. Older dogs, and dogs with respiratory compromise, had the greatest odds of the environmental type. Brachycephalic dogs had greater odds of all three types compared with mesocephalic dogs.
On outcome, the odds of death following a vehicular event were similar to those following an exertional one — reported as an odds ratio of 1.47, which did not reach statistical significance. In other words, this data does not show hot-car events to be more lethal per event; there are simply far fewer of them, while exertional events are common enough to kill more dogs overall.
What this study cannot tell you
It counts events that reached a veterinary practice. Dogs that overheated and recovered at home without a visit are invisible here, and so are dogs that died before arriving. The trigger proportions describe presenting cases, not everything that happens.
It also describes UK dogs in a single year, 2016. Climate, culture and typical exercise habits differ elsewhere, and the balance between triggers may differ with them.
The study identifies triggers and risk factors. It does not define a safe temperature, a safe duration, or a safe activity level for any individual dog, and it does not evaluate any prevention or treatment strategy.
Finally, the death-odds comparison between vehicular and exertional events was not statistically significant. It should be read as "no clear difference detected", not as "these are equally dangerous".
What pet owners should track
Most of the value here is in what you change rather than what you record, but a record helps for the dogs most at risk:
- Note if your dog has struggled in heat before, and at what temperature and activity level — a previous episode is the most specific information you can give a veterinarian
- Note recovery time after ordinary exercise on warm days, and whether it is getting longer across a season
- If your dog is flat-faced, overweight, elderly, or has any known breathing problem, record that plainly in the profile — this study found all of these groups carry raised risk
- Shift walks to the coolest parts of the day in warm weather, and treat a warm-but-not-hot day as still relevant
Heat-related illness is an emergency. Excessive panting that will not settle, distress, weakness, collapse, vomiting, or confusion on a warm day mean contacting a veterinarian immediately. Do not observe, do not record, do not wait — call.
What PAWai can help organize
PAWai can hold your dog's risk profile and the history of any previous heat episodes, so it is available rather than half-remembered when it matters. PAWai does not assess heat risk, does not tell you when it is safe to walk your dog, and gives no first-aid or cooling instructions. In an emergency, contact a veterinarian and follow their instructions — cooling advice in particular has changed with recent research and should come from your vet, not from a record-keeping app.
Disclaimer
PAWai organizes information and educates pet owners. PAWai does not diagnose conditions or recommend treatment. Always consult a licensed veterinarian for medical decisions about your pet.
Citation
Hall, E. J., Carter, A. J., & O'Neill, D. G. (2020). Dogs don't die just in hot cars — exertional heat-related illness (heatstroke) is a greater threat to UK dogs. Animals, 10(8), 1324. https://doi.org/10.3390/ani10081324
Hall, E. J., Carter, A. J., Chico, G., Bradbury, J., Gentle, L. K., Barfield, D., & O'Neill, D. G. (2022). Risk factors for severe and fatal heat-related illness in UK dogs — a VetCompass study. Veterinary Sciences, 9(5), 231. https://doi.org/10.3390/vetsci9050231