The UK heatwave has sparked an urgent warning to dog owners over a “silent killer” as highs of 34C are expected on Friday.

Pet owners have been urged to keep a close eye on their furry friends as temperatures soar.

The UK Health Security Agency (UKHSA) has issued a level 2 heat-health alert for a large part of southern and central England, with a level 1 alert in place for northern England.

The extreme weather has sparked a warning from dog specialists at the RSPCA.

Esme Wheeler said: "The truth is walking dogs in hot weather can be a silent killer.

 "While the majority would never leave our dogs in a car on a hot day, or even take our dogs for a really long walk in the heat, many people may still be putting their dogs at risk even on a short walk, or taking them to places such as fields and beaches with little or no shade.

"We have long-campaigned that dogs die in hot cars, but this year we’re highlighting that dogs die on hot walks, too. The message remains very simple – never leave a dog in a hot car because ‘not long’ is too long, and when it comes to walks, 'if in doubt, don’t go out.'"

Dr Dan O’Neill, associate professor companion animal epidemiology at the Royal Veterinary College, added: “Heat-related illness can lead to organ failure, brain damage and ultimately death.

“Most people know that dogs die in hot cars, but the reality is that more than 10 times as many dogs need veterinary treatment for heat-related illness following exercise as for being overheated in cars.

“It can take weeks for a dog to acclimatise to hot weather, so after a spell of cold weather, periods of hot weather can be particularly dangerous.”