In the UK, there is no law mandating the use of lights on dogs at night. So there is no legal requirement for dog owners to put safety lights on collars or harnesses. There are also no laws stating that dogs have to wear any sort of high visibility clothing.
Stay visible, stay safe
Although it’s not mandatory, using lights on your dog is a highly recommended safety measure at night and in low light conditions, like fog or heavy rain. Increasing your dog’s visibility to other dog walkers, motorists, and pedestrians can help reduce accidents.
If you let your dog off leash to enjoy open spaces at night, using a safety light or hi-vis gear will also make it far easier to keep track of your dog.
Rural dog owners might be very used to walking along country roads after dark with just a torch. But it’s recommended that both the owner and the dog wear reflective clothing to keep visible, even on familiar, quiet roads.