Flissie the boxer underwent surgery earlier this month after collapsing.

Owners Martin and Sue Read, from Sheringham, Norfolk, say the operation has "taken years" off their pet.

The pacemaker had previously been fitted to a human and was inserted into Flissie during a three-hour operation at a veterinary surgery.

The effect has been amazing - she's running round like she's two years younger Sue Read, dog's owner

"Three months ago she collapsed," said Mrs Read, who with her husband, runs an outdoor centre.

"She got to a stage where she could barely sit and the vet suggested that it was now possible to fit a pacemaker.

"The pacemaker is second-hand and had been used by a human being.

"And the effect has been amazing - she's running round like she's two years younger. She's a completely different dog."