After a surge in calls to the RSPCA about dogs in hot cars, an animal charity has said leaving a window open is not enough.

The Watford-based organisation, National Animal Welfare Trust (NAWT), said that in 22 degree heat a car can reach 47 degrees within an hour.

It said an open window or parking in the shade, are ‘not reliable’ forms of protection.

The trust’s CEO Clare Williams said: “Given summertime is a peak season for road travel, we wanted to warn people about the potential road blocks in their way with regard to their next trip.

“Most of us consider our pets family members, so be prepared for any unwelcome surprises by checking your legal responsibilities, your insurance and make sure your dog is secure while travelling.”

The charity also advised dogs should be secured in vehicles using a crate, guard or harness as one in five will be unprotected if there was an accident.