When do Old English Sheepdogs stop growing?

Old English Sheepdogs stop growing in height by around 12 to 18 months of age. However, they continue to fill out and gain muscle mass until they are about two to three years old. Like many large breeds, their growth plates take longer to close compared to smaller breeds, so it’s essential to feed them a balanced diet and avoid excessive joint strain (such as distance running or agility jumps) until they are at least 18 months old.