Hi my 6year old lab has started peeing in his bed at night 3 times in the last 6 weeks he seems healthy enough loads of energy he was a working dog in a kennel till 2 years ago after a few months he was house trained but now this has started I walk him 3 times a day

When was the last time he was examined by a Vet? It could be anything, a bladder infection, something else.