Dogs in Cars: UK Rules and How to Travel Safely
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In the UK, the Highway Code says dogs in a vehicle should be suitably restrained so they cannot distract you while driving or injure you, or themselves, if you stop quickly. A seat belt harness, pet carrier, dog cage or dog guard are the methods it names. Never leave a dog alone in a car on a warm day, and plan regular stops on longer journeys.
Here is what the rules actually say, the main ways to restrain a dog, and the habits that make long drives easier.
What the Highway Code says: Rule 57
Rule 57 sits in the section of the Highway Code about animals. It reads: "When in a vehicle make sure dogs or other animals are suitably restrained so they cannot distract you while you are driving or injure you, or themselves, if you stop quickly. A seat belt harness, pet carrier, dog cage or dog guard are ways of restraining animals in cars."
It is worth understanding how this rule works legally. The Highway Code explains that rules written with the words "must" or "must not" are legal requirements, and breaking them is a criminal offence. Rule 57 does not use that wording, so failing to follow it is not, in itself, an offence. However, the Code also states that it may be used in evidence in court proceedings under the Traffic Acts. A loose dog that distracts you could therefore become part of a wider case about your driving. Treat Rule 57 as the standard for every journey.
Your restraint options
There is no single right answer. The best choice depends on your dog's size, your car and how your dog copes with travel. These are the four methods the Highway Code names.
| Method | Suits | Things to consider |
|---|---|---|
| Seat belt harness | Dogs of most sizes travelling on the back seat | Attach to a properly fitted harness, never to a collar. Keep the tether short enough that your dog cannot reach the front seats. |
| Pet carrier | Small dogs and puppies | Secure the carrier so it cannot slide or tip, ideally in a footwell or belted onto a seat. Make sure there is good airflow. |
| Dog cage or crate | Medium and large dogs, estate cars and SUVs | Choose a size your dog can sit, stand and turn around in. Fix it so it cannot shift when you brake. |
| Dog guard | Dogs travelling in the boot of an estate or hatchback | A guard stops your dog climbing into the cabin. Check it is fitted firmly and suits your car model. |
Whatever you choose, introduce it at home first. Let your dog sniff and settle in a crate or carrier, or wear their harness for short spells, before a long drive. For small dogs, a lined carrier with a built in tether, such as The Everyday Travel Carrier (for pets up to 8kg), can double as a calm spot on the back seat when secured in place, and is easy to carry once you arrive.
Front seat or back?
The back seat, or the boot with a guard or crate, is the usual choice. A dog on the front seat is more likely to distract you. If you have no other option, push the seat back, use a secure restraint and check your car manual about the airbag.
Never leave a dog in a hot car
This is the most important rule of all. RSPCA figures, repeated in a 2025 police warning, show that when it is 22 degrees outside, a car can reach 47 degrees within an hour. Parking in the shade or leaving the windows slightly open does not make it safe. Heatstroke can be fatal for dogs.
- Do not leave your dog alone in the car on a warm day, even "just for a minute".
- On summer journeys, plan stops where your dog can come with you, or travel with someone who can stay with the dog outside the car.
- Run the air conditioning or ventilation while driving, and avoid the hottest part of the day where you can.
- If you see a dog in distress alone in a hot car, call 999.
For more on keeping cool, see our guide to dogs in hot weather.
Long drives: breaks, water and comfort
A comfortable dog is a calmer passenger. Before a long drive:
- Walk first. A good walk before you set off helps your dog settle and gives them a chance to go to the toilet.
- Feed lightly. Some dogs feel travel sick on a full stomach, so a small meal a few hours before leaving is often kinder than a big breakfast.
- Plan regular stops. Build in breaks for a short walk on the lead, a drink and a toilet stop. Service areas and lay-bys are busy places, so keep the lead on before you open the door.
- Bring water. A leakproof bottle with a built in bowl, like The Companion water bottle, makes a quick drink easy at every stop.
- Bring familiar things. A blanket that smells of home can help an anxious traveller settle.
Check their ID before you go
A new place, an open car door and a nervous dog is exactly when escapes happen. By law, your dog must wear a collar with your name and address on the collar or on a plate or tag attached to it when in a public place, and in England dogs over eight weeks must be microchipped and registered. Add a phone number too. Our engraved collars, such as The Mayfair Collar, carry your dog's name and your number, so pair one with an address tag to meet the legal minimum. Make sure your microchip details are up to date before you travel.
Helping a nervous traveller
Short, positive practice runs help anxious dogs: sit in the parked car with treats, then drive around the block. If your dog is regularly sick or distressed in the car, speak to your vet.
For the rest of your trip, our complete dog travel and London guide brings everything together, and our holiday packing list covers what to bring. If you prefer the train, read our guide to travelling with a small dog in the UK.
Frequently asked questions
Is it illegal to have an unrestrained dog in the car in the UK?
Rule 57 of the Highway Code says dogs should be suitably restrained, but it is not written as a "must" rule, so ignoring it is not an offence in itself. The Code can, however, be used in evidence in court proceedings under the Traffic Acts.
What counts as a suitable restraint?
The Highway Code lists a seat belt harness, pet carrier, dog cage or dog guard as ways of restraining animals in cars.
Can I leave my dog in the car with the windows open?
Not on a warm day. Shade and slightly open windows do not stop a car overheating. RSPCA figures show a car can reach 47 degrees within an hour when it is 22 degrees outside.
What should I do if I see a dog in a hot car?
If the dog is showing signs of distress, call 999.