The Bulldog is a British breed of dog of mastiff type. It may also be known as the English Bulldog or British Bulldog. It is of medium size, a muscular, hefty dog with a wrinkled face and a distinctive pushedin nose. It is commonly kept as a companion dog; in 2013 it was in twelfth place on a list of the breeds most frequently registered worldwide.

Appearance
Bulldogs have characteristically wide heads and shoulders along with a pronounced mandibular prognathism. There are generally thick folds of skin on the brow; round, black, wideset eyes; a short muzzle with characteristic folds called a rope or nose roll above the nose; hanging skin under the neck; drooping lips and pointed teeth, and an underbite with an upturned jaw. The coat is short, flat, and sleek with colours of red, fawn, white, brindle, and piebald.

In the United Kingdom, the breed standards are 55 lb (25 kg) for a male and 50 lb (23 kg) for a female.[8] In the United States, a typical mature male weighs 50 lb (23 kg), while mature females weigh about 40 lb (18 kg).The Bulldog Club of America recommends the average weight of a bulldog to be 40–50 lb (18–23 kg).

Bulldogs are one of the few breeds whose tail is naturally short and either straight, screwed or thin and thus is not cut or docked as with some other breeds. A straight tail is a more desirable tail according to the breed standard set forth by the BCA if it is facing downward, not upward.

Temperament
According to the American Kennel Club (AKC), a Bulldog's disposition should be "equable and kind, resolute, and courageous (not vicious or aggressive), and demeanor should be pacifist and dignified. These attributes should be countenanced by the expression and behavior"
Breeders have worked to reduce/remove aggression from these dogs.

Most have a friendly, patient, but stubborn nature. Bulldogs are recognized as excellent family pets because of their tendency to form strong bonds with children.

Generally, Bulldogs are known for getting along well with children, other dogs, and other pets.

Health and Lifespan
A 2004 UK survey of 180 Bulldog deaths puts the median age at death at 6 years 3 months. The leading cause of death of Bulldogs in the survey was cardiac related (20%), cancer (18%), and old age (9%). Those that died of old age had an average lifespan of 10 to 11 years. A 2013 UK vet clinic survey of 26 Bulldogs puts the median lifespan at 8.4 years with an interquartile range of 3.2–11.3 years. The UK Bulldog Breed Council website lists the average life span of the breed as 8–10 years.

Statistics from the Orthopedic Foundation for Animals indicate that of the 467 Bulldogs tested between 1979 and 2009 (30 years), 73.9% were affected by hip dysplasia, the highest amongst all breeds. Similarly, the breed has the worst score in the British Veterinary Association/Kennel Club Hip Dysplasia scoring scheme, although only 22 Bulldogs were tested in the scheme. Patellar luxation affects 6.2% of Bulldogs.

Some individuals of this breed are prone to interdigital cysts—cysts that form between the toes. These cause the dog some discomfort, but are treatable either by vet or an experienced owner. They may also suffer from respiratory problems. Other problems can include cherry eye, a protrusion of the inner eyelid (which can be corrected by a veterinarian), allergies, and hip issues in older Bulldogs.

Over 80% of Bulldog litters are delivered by Caesarean section because their characteristically large heads can become lodged in the mother's birth canal. The folds, or "rope", on a Bulldog's face should be cleaned daily to avoid infections caused by moisture accumulation. Some Bulldogs' naturally curling tails can be so tight to the body as to require regular cleaning and ointment. Due to the high volume of skin folds on the Bulldog's body, they have high prevalence of skinfold dermatitis.