The Met said the officer works for central operations, which includes the dog support unit. The deaths came on the same day that police rescued two dogs from cars in Bath. Meanwhile, officers are warning dog owners to use common sense in the hot weather and say owners who put animals at risk in cars can face a maximum of six months in prison and a £20,000 fine.

Last year, police dog handler PC Mark Johnson, 40, was given a six-month conditional discharge and fined £2,500 after he left two German shepherds to die in a baking hot car.

The dogs suffered severe heatstroke and died of kidney failure and a brain haemorrhage after going through ‘excruciating pain’ when they were left outside Nottingham Police headquarters in July 2009. A spokeswoman for the Dogs Trust, the UK’s largest dog welfare charity, said it was ‘saddened’ to hear of the two latest deaths.

She added: ‘It can take just 20 minutes for a dog to die and temperatures can reach over 40C (104F) in some vehicles.’

A spokeswoman for the RSPCA said the charity’s 6,000 calls a year about dogs that have been left in hot cars may be ‘the tip of the iceberg’.

Leaving a window open makes little difference, she said.