Heatwaves don't only kill dogs left in cars.

That's the common misconception to correct first.

A dog walking at noon, a poorly ventilated attic apartment, a sports outing in 28°C weather with a bulldog: these are equally dangerous situations.

Since 2000, heatwaves have returned to France every year, compared to once every five years before 1989 (Ministry of Ecological Transition, National Heatwave Management Plan, 2023).

Faced with this growing risk, dog owners need reliable guidance. 

This article is based on the best available data, largely from the work of the Royal Veterinary College (RVC) in the United Kingdom.

Why British data?

Because there is currently no equivalent in France to the VetCompass program, which continuously collects and analyzes clinical records from hundreds of thousands of dogs seen in veterinary practices.

This work is internationally recognized, including by French veterinarians, and the physiological mechanisms of heatstroke are the same regardless of the country. The resulting recommendations apply everywhere.

Why heat is dangerous for dogs 

Dogs do not sweat like we do.

They regulate their temperature mainly by panting, which allows water to evaporate from their respiratory tracts.

When the external heat exceeds their ability to dissipate internal heat, their body temperature rises and the body begins to malfunction.

According to VetCompass data from the Royal Veterinary College (Hall et al., Scientific Reports, 2020, PMID 32555323), covering over 900,000 dogs followed in primary care in the UK, the fatality rate associated with pathological heat cases managed by a veterinarian was 14.18%.

In the most severe cases, survival drops below 43% (Hall et al., Veterinary Sciences, 2022, PMID 35622759).

These figures are not meant to alarm: they are there to make us understand that we don't have the luxury of waiting.

The French Ministry of Agriculture reminds us in its official Heatwave Plan: Article L.214-1 of the Rural Code requires all animal owners to provide conditions compatible with their biological imperatives, including during periods of intense heat.

This is a legal obligation, not just common sense advice.

Which dogs are most at risk?

VetCompass data identifies brachycephalic morphology, obesity, and underlying conditions affecting the respiratory or circulatory systems as major risk factors (Hall et al., Veterinary Sciences, 2022, PMID 35622759).

In concrete terms: a French Bulldog, a Pug, a Boxer, a Shih-Tzu, a Pekingese are profiles to monitor first as soon as temperatures rise.

Their facial anatomy makes panting less effective, which reduces their thermal safety margin compared to other breeds.

Older dogs, overweight dogs, or dogs that have performed intense physical exertion are also in an increased vigilance zone.

What are the most common mistakes during a heatwave?

The car, even for "two minutes".

At 22°C outside, a car's interior can reach 47°C in one hour.

Neither shade nor partially open windows provide effective protection (RSPCA, Dogs in Hot Cars).

Outings at the wrong times and in the wrong places. 

Reserve walks for early morning and late evening. Prioritize shade, light-colored pavements, avoid manholes, metal grates, asphalt, and tarmac as much as possible...

To test the ground: if your hand (or bare foot) cannot tolerate contact with the asphalt for five seconds, it's too hot for their paw pads (RSPCA, Summer dog safety).

Poorly reasoned grooming. 

Do not shave a dog "to cool it down" without veterinary advice or a competent groomer's opinion, especially for double-coated breeds!

The correct approach is to brush regularly, avoid matting, and ensure that water reaches the skin if you are wetting the dog to cool it down.

The Riney Canine Health Center at Cornell University reminds us that double-coated dogs should be wet to the skin during cooling procedures (Cornell University College of Veterinary Medicine).

Areas to wet: 

Chest

Armpits

Lower belly

Groin

Paws / paw pads

Base of the neck

Areas NOT to wet:

Head

Eyes

Muzzle

Ears

Back

Believing that a quick recovery solves the problem. 

A dog may seem better after cooling but may still have experienced a serious episode.

VetCompass data shows that the most severe forms are associated with neurological signs, gastrointestinal bleeding, or coagulation disorders (Hall et al., Scientific Reports, 2021, PMID 33782494).

A veterinary consultation is therefore necessary after suspected heatstroke.

What are the warning signs to watch for?

The most frequent signs in cases documented by VetCompass are respiratory changes (68.73% of cases) and lethargy (47.79%) (Hall et al., Scientific Reports, 2021, PMID 33782494).

The signs associated with the highest risk of death in VetCompass data are neurological disorders, gastrointestinal hemorrhages, and coagulation disorders (Hall et al., Scientific Reports, 2021).

Do not wait to get a thermometer or know an exact number. 

If your dog shows several of these signs in a context of heat or exertion, act immediately.

What to do in case of suspected heatstroke

The central principle, based on current RVC recommendations, is: cool first, transport second.

The Royal Veterinary College is explicit: start cooling immediately, because the longer the body temperature remains elevated, the more damage accumulates.

VetCompass data shows that only 21.7% of dogs had been cooled before transport between 2016 and 2018.

This deficit is directly associated with poorer clinical outcomes (Hall et al., Veterinary Sciences, 2023, PMC10385239).

1. Move your dog into the shade in a cool, ventilated area.

2. Cool them with water without losing time. Immersion in cold water is recommended for young, healthy dogs. For older dogs or those with medical histories, pour water cooler than the dog's temperature, combined with air movement: fan, air conditioning, or natural breeze (Royal Veterinary College, "Cool first, transport second" recommendations). Avoid pouring water directly on the head or into the mouth: the goal is to cool the body without risking interference with breathing.

3. Offer water to drink in small quantities, without forcing.

4. Call your veterinarian as soon as possible, even if your dog seems to be stabilizing.

What not to do

•        Don't waste time with symbolic methods: a misting spray or a dry towel are not enough. Use fresh to cold water as available, with air if possible, and start immediately.

•        Do not give human anti-inflammatories or painkillers

•        Do not assume that a quick recovery means everything is fine

•        Do not delay a veterinary consultation, even if your dog seems stable

Summary

Sources:

1.     Hall EJ, Carter AJ, O’Neill DG. Incidence and risk factors for heat-related illness (heatstroke) in UK dogs under primary veterinary care in 2016. Scientific Reports. 2020 ;10(1) :9128. DOI : 10.1038/s41598-020-66015-8. PMID 32555323.

2.     Hall EJ, Carter AJ, Bradbury J, Barfield D, O’Neill DG. Proposing the VetCompass clinical grading tool for heat-related illness in dogs. Scientific Reports. 2021 ;11(1) :6828. DOI : 10.1038/s41598-021-86235-w. PMID 33782494.

3.     Hall EJ, Carter AJ, Chico G, Bradbury J, Gentle LK, Barfield D, O’Neill DG. Risk Factors for Severe and Fatal Heat-Related Illness in UK Dogs — A VetCompass Study. Veterinary Sciences. 2022 ;9(5) :231. DOI : 10.3390/vetsci9050231. PMID 35622759.

4.     Hall EJ, Carter AJ, O’Neill DG et al. Cooling Methods Used to Manage Heat-Related Illness in Dogs Presented to Primary Care Veterinary Practices during 2016–2018 in the UK. Veterinary Sciences. 2023. PMC10385239.

5.     Beard S, Hall EJ, Bradbury J, Carter AJ, Gilbert S, O’Neill DG. Epidemiology of heat-related illness in dogs under UK emergency veterinary care in 2022. Veterinary Record. 2024. DOI : 10.1002/vetr.4153.

6.     Cornell University College of Veterinary Medicine, Riney Canine Health Center. Summer heat safety tips for dogs. Disponible sur : vet.cornell.edu.

7.     Royal Veterinary College. Heatstroke in dogs and cats — prevention, symptoms and first aid tips. Recommandations « Cool first, transport second ». Disponible sur : rvc.ac.uk/vetcompass.

8.     RSPCA. Dogs in Hot Cars. RSPCA. Keeping Your Dog Safe in Summer. Disponible sur : rspca.org.uk.

9.     Ministère de l’Agriculture et de la Souveraineté alimentaire, Direction générale de l’alimentation (DGAL). Fiche Plan Vagues de Chaleur — Recommandations pour les détenteurs d’animaux. Disponible sur : agriculture.gouv.fr.

10. Ministère de la Transition écologique. Plan national de gestion des vagues de chaleur, 2023. Disponible sur : ecologie.gouv.fr.