In the 17th and 18th century, the Old English Bulldog had many different strains for cattle-droving, bull-baiting, farm dogs, and butcher's dogs.Bull-baiting was also a common blood sport of the era and though there is evidence of such migrating to America with the landrace bulldogs brought by working class Englishmen in colonial times, it is also certain that the strains that migrated to America were unaffected by the banning of the sport in 1835 in the U.K. and, therefore, there was no need for a decline in the population of the old-type bulldog. Later, breeding decisions were dependent on the best working farm dogs, despite breed or background. Some health problems in American bulldogs are often found within certain genetic lines, and are not common to the entire breed, while others, such as neuronal ceroid lipofuscinosis (NCL), Ichthyosis, disorders of the kidney and thyroid, ACL tears, hip dysplasia, cherry eye, elbow dysplasia, entropion, ectropion, and bone cancer are more common to the general population of American Bulldogs.