Check that chip
Approximately 7000 (yes! that's seven thousand), healthy dogs are put to sleep every year in the UK. If a stray dog is taken to a pound and is not get claimed within 7 days it will likely be put to sleep.
There is now no single agency overseeing the handling and processing of lost /stray dogs. Make sure your chip details are up to date - ring the chip company asap and check.
Some owners think a microchip can tell them where there dog is - it can't. Your dog needs to be caught and taken to a place where it can be scanned.
It can also cost £100's to get your dog back - plus all the stress and heartache.
Be pro-active and get a TAGZ GPS tracker - find them before they get lost.