The Old English Mastiff is a massive dog. The Mastiff has a large, heavy, square head with a well-marked stop between the eyes. The muzzle should be half the length of the skull. The medium-sized brown to dark hazel eyes are set wide apart with a black mask around them.

Personality: The mastiff is a dignified yet good-natured animal. He is loving and affectionate toward his family, and his calm demeanor makes him a good companion for older children. However, the breed is not recommended for toddlers because of its great size.

Unfortunately, this large and lovable breed commonly suffers from canine cataracts, eyelid abnormalities (ectropion and entropion), progressive retinal atrophy, corneal dystrophy, retinal dysplasia and prolapse of the nictitans gland commonly referred to as cherry eye.