The Bull Terrier is a breed of dog in the terrier family. There is also a miniature version of this breed which is officially known as the Miniature Bull Terrier.
The Bull Terrier's most recognizable feature is its head, described as 'egg-shaped' when viewed from the front; the top of the skull is almost flat. The profile curves gently downwards from the top of the skull to the tip of the nose, which is black and bent downwards at the tip, with well developed nostrils. The under-jaw is deep and strong. The unique triangular eyes are small, dark, and deep-set. Bull Terriers are the only dogs that have triangular eyes. The body is full and round, with strong, muscular shoulders. The tail is carried horizontally. They are either white, red, fawn, black, brindle, or a combination of these.
Bull Terriers can be both independent and stubborn and for this reason are not considered suitable for an inexperienced dog owner. A Bull Terrier has an even temperament and is amenable to discipline. Although obstinate, they are particularly good with people. Early socialisation will ensure that the dog will get along with other dogs and animals. Their personality is described as courageous, full of spirit, with a fun-loving attitude, a children-loving dog and a perfect family member. A 2008 study in Germany showed that Bull Terriers have no significant temperament difference from Golden retrievers in overall temperament researches.
All puppies should be checked for deafness, which occurs in 20.4% of pure white Bull Terriers and 1.3% of colored Bull Terriers and is difficult to notice, especially in a relatively young puppy. Many Bull Terriers have a tendency to develop skin allergies. Insect bites, such as those from fleas, and sometimes mosquitoes and mites, can produce a generalised allergic response of hives, rash, and itching. This problem can be stopped by keeping the dog free of contact from these insects, but this is definitely a consideration in climates or circumstances where exposure to these insects is inevitable. A UK breed survey puts their median lifespan at 10 years and their mean at 9 years (1 s.f., RSE = 13.87% 2 d. p.), with a good number of dogs living to 10–15 years.