Dog owners are being warned not to leave their pets inside vehicles as England heads for its first very hot spell of the summer.

Parts of the south east are expected to be hotter than Marbella and Ibiza this weekend – prompting an amber heat health alert warning that urges people to check in on the vulnerable.

But as households gear up for a weekend of fun in the sun, animal organisations and the emergency services have issued strongly-worded warnings to owners who may be tempted to leave animals inside a vehicle even if they think it’s only going to be for a short amount of time.

The RSPCA, constabularies, local councils and The Dogs Trust are spreading the word across social media with the message ‘Dogs die in hot cars’.

In a Tweet, alongside a poster, The Dogs Trust wrote: “With temperatures set to increase this week we’re here to remind you never to leave your dog in a vehicle.”

The British Veterinary Association says no animal should be left in conservatories, caravans or cars when the weather is even remotely warm - warning that temperatures can rise in such environments extremely quickly.

Temperatures in England are forecast to tip 30C in some areas this Saturday and Sunday – but animal charities say even just 22C outside can very rapidly become a sweltering 47C inside well within an hour which could ultimately cause the death of a pet.

While police forces are often reported as having swiftly freed dogs spotted left in hot cars, the rules are slightly different for a member of the public who notices a dog alone.

But with the RSPCA describing heatstroke in dogs as the 'silent killer' what should you do if you see a dog inside a car on a hot day?

RSPCA and British Veterinary Association advice

The RSPCA has published advice on its website that outlines what people can do if they find a dog inside a car.

The first thing, it says, is to assess the animal's condition, and if they're showing any signs of heatstroke dial 999 straight away.

The RSPCA acknowledges, that if the animal's condition is felt to be critical, and police aren't yet on the scene, a person's instinct will be to break the car to free them. It adds: "But please be aware that this could be classed as criminal damage. You may need to defend your actions in court, so please be sure you're doing the right thing.

"Legally, you can commit damage if you believe the car owner would consent to it if they knew the dog was in danger."

If you're absolutely sure you need to free the dog using force, explains the charity, it recommends first telling the police on the phone what you intend to do and why.

Taking photos and videos of the dog in distress, and finding witnesses to the incident alongside making a note of the names and telephone numbers of anyone else who is watching or helping is also advisable.

The BVA adds: "The law states that you have a lawful excuse to commit damage if you believe that the owner of the property that you damage would consent to the damage if they knew the circumstances."

Helping a dog who appears OK

If the dog doesn't seem in distress or in immediate danger you can leave them in the car, says the RSPCA, and take other remedial action instead.

This, it suggests, might include attempting to work out how long the animal has been inside - perhaps using any pay and display ticket on the vehicle for clues.

It's also advisable to make a note of the car's make, colour and registration because if you feel that the owner has put the dog in danger you can still report the incident to police.

If you're at a shop, venue or event and you see an animal alone in a car, the charity advises asking staff to alert owners over a loudspeaker or tannoy. And where possible you, or someone else, should stay with the dog to monitor its condition until someone returns.

If they do begin to get worse be prepared says the RSPCA to ring 999 and speak to police.

You can also call the charity’s own cruelty line for advice on 0300 1234 999, but if a dog is in danger alerting the emergency services should always be your first step.