More than 4,700
Stray dogs in the UK couldn't be reunited with their owners last year due to outdated microchips, animal charity Dogs Trust has said.
The charity found 37,283 dogs were left unclaimed in local authority kennels between April 2015 and March 2016.
One in eight were pets that could not be returned as their microchips had not been updated by their owners, it said.
In April, it became a legal requirement for all pet dogs to be microchipped with current contact details.
The results come from the organisation's annual survey of local authorities, which also revealed 3,463 stray dogs had been destroyed in the last year.
Jon Gerlis from the Dogs Trust told BBC Radio 4's Today programme: "We took a poll which found that only 9% of people saw updating their dog's microchip as a priority when they move home - that compares, unfavourably, to updating their digital television set."
"When you move home, a dog doesn't know its surroundings, but it naturally wants to go home, so it's probably the most crucial time in actually making sure that your chip details are up to date - especially if you don't have secure borders in your garden," he added.
Credit BBC News