It’s a summer’s day, and you’re on the way home from walking your four-legged pal when you remember you need to swing by the grocery store to collect some ingredients for dinner. Will it be OK to leave your dog in the car for 20 minutes, if you park in the shade?
Not so much. “It is rarely okay to leave your dog in a car, even on cool days,” states Dr. Carly Fox, a senior veterinarian in the Emergency & Critical Care Service at the Schwarzman Animal Medical Center. “A 21°C day outside can cause temperatures inside cars to reach nearly 38°C—and dogs can overheat very quickly, especially brachycephalic dogs.”
Let’s take a closer look at the hazards that hot cars can pose to our canine pals—and why leaving your car window open is not a solution.
How Hot Can It Get Inside a Car?
Temperatures can reach notable heights in cars, and faster than you might expect.
As data from NoHeatStroke.org shows, outside temperatures—even on “cooler” days—can quickly feel much hotter in cars. The chart below shows how rapidly car temperatures can rise inside a car.
| Outside temperature | Time passed | Car temperature |
| 21°C/70°F | 5 minutes | 26.6°C/80°F |
| 15 minutes | 34.4°C/94°F | |
| 30 minutes | 40°C/104°F | |
| 26.6°C/80°F | 5 minutes | 32.2°C/90°F |
| 15 minutes | 40°C/104°F | |
| 30 minutes | 45.5°C/114°F | |
| 32.2°C/90°F | 5 minutes | 37.7°C/100°F |
| 15 minutes | 45.5°C/114°F | |
| 30 minutes | 51.1°C/124°F |
It’s also tricky to predict other factors that could affect your dog when they’re waiting in your car—such as humidity and sun intensity or your pet’s stress levels or underlying health conditions, says Dr. Kaylyn Tarver, DVM, emergency veterinarian at VEG ER for Pets in Pleasant Hill. For example, as the sun moves, so will the shady spot, leaving your dog exposed to the sun’s rays.
Open windows won’t solve high temperatures
“Keeping a window open does not make leaving a dog in a car safe during summer,” states Dr. Tarver. “Temperatures inside a parked car can rise dramatically, even with a window cracked.”
A 2005 study looking at temperatures in cars that had a window left slightly open revealed that things can still get very hot. In outside temperatures of 32°C, inside temperatures reached almost 42°C in just 10 minutes, and 48°C in 30 minutes.
Be careful re-entering your car
If your car has been in the sun for a few minutes, the seats may overheat and burn your paws, especially if the seats are leather. Fortunately, you can take steps to help minimise the risk. For instance, “if you know the seats can get particularly hot after sitting in a parking lot, make sure to have a blanket available to cover them for your dog to lie on,” suggests Dr Fox.
If travelling from home, she advises starting your car earlier to allow the AC to cool down the car before you get in.
Health Risks Of Leaving Your Dog In a Car
According to the Royal Veterinary College’s latest study on heatstroke, one in ten vets who care for small animals had seen at least one dog with heatstroke after being left in a hot car during a heatwave in 2022. Of all the dog’s with heatstroke, one in four died.
Heatstroke can be a fatal health condition, resulting in seizures and organ failure, and this can happen rapidly to a dog in a hot car. Signs of heatstroke include panting, vomiting, excessive drooling, and stumbling.
Dr Tarver says other health issues can also arise:
- Dehydration: Leading to issues ranging from weakness and lethargy to kidney damage or failure
- Shock: Can lead to sepsis (which poses a death risk) or issues relating to the immune system or heart
- Multi-system organ failure: Heat can affect a dog’s organs, leading to internal bleeding and permanent damage
- Gastrointestinal damage: Effects range from vomiting and diarrhoea to chronic issues, such as malabsorption
- Neurological damage: High temperatures can cause brain swelling, resulting in seizures and loss of consciousness, and may lead to permanent neurological damage
Infographic by Rover
What other risks do cars pose to dogs?
Even if it’s not beach-friendly weather outside, leaving your dog in a car can pose other risks to their physical and mental well-being.
“Physical injuries can occur from chewing harmful objects, entanglement, or escape attempts,” says Dr Tarver. She notes that poor ventilation may lead to breathing difficulties, while being left alone (especially in a confined space) can cause dogs to feel anxious or distressed, which, in turn, may trigger pre-existing medical conditions.
Plus, Dr. Tarver adds, it’s important to consider the theft risk associated with leaving your dog unattended.
Is It Illegal to Leave a Dog In a Car?
In the UK, leaving a dog in a hot car isn’t technically breaking any laws. However, pet parents have a legal responsibility for their dog’s welfare and health. If a dog develops illnesses or dies due to being alone in a hot car, the pet parents could face a fine, jail time, or both under the Animal Welfare Act of 2006.
If you have to leave your dog in a car, make sure…
In an emergency situation, you may need to leave your dog in the car for a few minutes. If you have absolutely no other option, Dr. Fox recommends the following steps:
- Leave your car’s temperature control system on to avoid heat increases
- Keep your car (and dog) in view or ask someone to keep an eye on them while you’re away
- Park in a shady spot
- Ensure your dog can access a water bowl
- Leave a note for passers-by to help avoid a rescue break-in
However, as noted in the chart above, even 5 minutes can be risky. It is recommended to keep your dog at home rather than leaving them unattended in a car. The above precautions do not guarantee your dog will be OK.
What to Do If You See a Dog In a Hot Car
If you see a dog left unattended in a hot car and in distress and have a reasonable belief that their life is at risk, taking the following steps can help ensure their well-being and safety:
- Take a photo of the car and its license plate on your phone.
- Call the police. The Royal Society for the Prevention of Cruelty to Animals (RSPCA) may not be able to get to the dog in time.
- If you’re near any shops, ask the manager or a security guard to make an announcement giving a description of the car and its license plate to notify the owner.
- Wait by the car until the owner returns.
You may feel the instinct to break into the car to free the dog if they’re in critical condition. However, UK law would class this as criminal damage, and you may need to defend yourself in court. Do not act unless you’re sure that you’re acting in the dog’s best interests and doing the right thing.
If you deem it necessary to free a dog in a hot car, protect yourself by taking the following actions:
- Contacting law enforcement before taking any action
- Taking pictures or videos of the dog to support your case
- Looking for nearby witnesses and taking their names and telephone numbers
- Using no more force than necessary to enter the car
- Staying with the animal until law enforcement arrives
The following signs may indicate a dog is in pain due to high temperatures. According to Dr. Tarver, the symptoms occur in order of progression:
- Excessive panting
- Excessive drooling
- Restlessness, pacing, or whining
- Lethargy or weakness
- Pale or bright red gums
- Vomiting and/or diarrhoea
- Stumbling or trouble coordinating movements
- Increased, rapid heart rate
- Collapsing or seizures
Remind Your Friends and Family About the Risks
While leaving a dog in a hot car poses various health and safety concerns, chilly conditions can be just as hazardous and lead to issues such as hypothermia. As a general rule, Dr. Fox advises people to avoid leaving their dog in the car when the outside temperature is above 15.56°C.
“Leaving your pet in the car when it is cold out can also be dangerous, as cars can retain cold temperatures like fridges,” she adds. The best option, states Dr. Fox, is to leave your dog at home or take them with you on errands.
Educating your family, friends, and neighbours can also help prevent beloved dogs (and other pets) from overheating or dying in hot cars. If you are going on holiday and leaving your dog with a sitter, remind them not to take your dog on any errands in the car.
