When does an American Bobtail stop growing?

An American Bobtail stops growing around two to three years of age. This breed is slower to mature, typically reaching their full height around 18 months and continuing to fill out until their second or third birthday. 

During their first year, they experience the most rapid growth, but they continue to develop and mature physically until they are about three years old. This slow maturation process is part of what makes them unique and contributes to their robust and muscular build.