I have a 4 month old labrador retriever who seems to have permanent loose bowel movements. They aren't always watery, but are always soft and leave residue when trying to pick them up. We haven't altered his diet recently, but wanted people's opinions on whether it could be his food, which is dry kibble (Hill's Science Puppy Food). He weighs around 13kg and I'm following the feeding guide on the bag. Any advice welcomed?