Short answer: “bully breed” is an informal umbrella term, not a breed. It covers dogs descended from the old British Bulldog — used for bull-baiting, which the AKC notes England banned in 1835 — and from the Bulldog-and-terrier crosses that followed. That includes the Pit Bull, Staffordshire and Bull Terriers, the Bulldog breeds and the Bullmastiff. The label describes ancestry and build, not temperament.
“Bully dog” isn’t a breed at all — it’s an umbrella term covering a whole family of breeds, and understanding where that label actually comes from clears up a lot of confusion about what a “bully breed” dog is actually like to own.
Where Does the Term “Bully Breed” Come From?
The term traces back to Britain’s bull-baiting Bulldogs. According to the AKC, bull-baiting was popular in Britain from the 13th century, and Bulldogs were bred for gripping strength and tenacity against much larger animals. After England banned blood sports with animals in 1835, the AKC’s Bull Terrier history explains, dogfighting went underground and gamblers crossed Bulldogs with terriers — producing the early bull-and-terrier types behind the Bull Terrier, the Staffordshire Bull Terrier and, in America, the Pit Bull. Others went a different direction: gamekeepers crossed Mastiffs with Bulldogs to create the Bullmastiff, and Bulldog admirers bred the fighting out of the Bulldog itself.
That history is part of why “bully breed” carries an outsized reputation today — one that doesn’t reflect what most modern versions of these breeds are bred for.
Which Breeds Count as Bully Breeds?
- American Pit Bull Terrier and American Staffordshire Terrier — often the breeds people picture first
- American Bully — a newer, purpose-bred companion breed descended from the Pit Bull (see American Bully vs Pitbull)
- Staffordshire Bull Terrier and Bull Terrier — British bull-and-terrier breeds with their own distinct standards
- Bullmastiff and Boxer — larger Bulldog- and mastiff-descended breeds, less commonly labeled this way but sharing the ancestry
- Bulldog breeds (English, French, American) and Boston Terriers — companion-sized breeds that descend directly from the Bulldog
How Different Are the Bully Breeds?
Very. Sizes range roughly tenfold across the group:
| Breed | Recognized by | Typical weight | Where it came from |
|---|---|---|---|
| Boston Terrier | AKC (1893) | 12–25 lb | Bulldog × white English Terrier, 1860s–70s |
| French Bulldog | AKC (1898) | Under 28 lb | Toy Bulldogs taken to France by English lace workers |
| Staffordshire Bull Terrier | AKC (1974) | 24–38 lb | English bull-and-terrier fighting dogs |
| American Pit Bull Terrier | UKC (first registered 1898); not AKC | 30–60 lb | Bull-and-terrier crosses brought to the US |
| Bulldog | AKC (1886) | 40–50 lb | Bull-baiting dogs, bred calmer after 1835 |
| American Staffordshire Terrier | AKC (1936) | 40–70 lb | Staffordshire Terriers bred larger in the US |
| Bull Terrier | AKC (1885) | 50–70 lb | Bulldog × terrier |
| Boxer | AKC (1904) | About 50–80 lb | German Bullenbeisser × English mastiff-type |
| American Bulldog | AKC Foundation Stock Service (2019) | 60–100 lb | Farm catch dog in the American South |
| Bullmastiff | AKC (1934) | 100–130 lb | Mastiff × Bulldog “gamekeeper’s night dog” |
Sources: AKC breed pages; UKC American Pit Bull Terrier standard. The American Bully (ABKC since 2004, UKC since 2013) comes in Pocket, Standard/Classic and XL sizes.
Are Bully Breeds Naturally Aggressive?
No — the term describes shared ancestry and a general physical type, not temperament. Registry standards point the same way: the UKC Pit Bull standard calls aggression toward humans “uncharacteristic of the breed and highly undesirable,” though it notes many APBTs show some aggression toward other dogs and need careful socialization.
Research backs up judging the individual. A 2022 study in Science found breed explains just 9% of behavioral variation in individual dogs. Labels are also shaky: when University of Florida researchers compared shelter staff’s visual calls with DNA, staff labeled 52% of dogs pit bull-type while DNA identified 21%. Strength and size still make training and socialization genuinely important, as with any powerful dog. For one breed’s temperament in detail, see Staffordshire Bull Terrier temperament.
Do Laws and Insurers Treat Bully Breeds Differently?
Often, and usually by type rather than exact breed:
- US: the Insurance Information Institute notes some home insurers won’t cover breeds they consider dangerous, such as pit bulls, while Pennsylvania and Michigan restrict breed-based denials in some policies.
- UK: the Pit Bull Terrier and XL Bully are banned types, judged by what a dog looks like rather than its breed or name — see our XL Bully legal status guide.
- India: a March 2024 central circular targeting the Pitbull Terrier, American Staffordshire Terrier, American Bulldog and other breeds was set aside by the Delhi High Court in April 2024; local rules may still apply.
One naming trap: the Bully Kutta is a South Asian mastiff type, not part of this family.
What Should You Actually Judge Before Getting a Bully Breed?
- Meet the individual dog or, for a puppy, its parents — temperament varies far more within the bully category than the umbrella term suggests
- Ask about the specific breed or mix, not just “bully,” since care needs and size range enormously across this group
- Check local breed-specific legislation and your insurance/housing situation, since many restrictions target “bully breeds” or “pit bull-type” dogs broadly rather than any one specific breed
- Prioritize a breeder or shelter that’s transparent about lineage and any known behavioral history
- For flat-faced members of the family, ask about breathing — our guide to French Bulldog breathing and joint issues explains what to look for
This article is for informational purposes only and does not replace guidance from your veterinarian. It is general information, not legal advice.
Sources
- American Kennel Club — breed pages for the Bulldog, Bull Terrier, Staffordshire Bull Terrier, American Staffordshire Terrier, Boston Terrier, French Bulldog, Boxer, Bullmastiff and American Bulldog
- United Kennel Club — American Pit Bull Terrier breed standard, revised May 2017
- Morrill K. et al. — Ancestry-inclusive dog genomics challenges popular breed stereotypes, Science, April 2022
- Olson K.R. et al. — Inconsistent identification of pit bull-type dogs by shelter staff, The Veterinary Journal, November 2015
- Insurance Information Institute — Spotlight on: Dog bite liability
- GOV.UK — Controlling your dog in public: banned dogs
- LiveLaw — Delhi High Court quashes Centre’s circular banning sale and breeding of “dangerous & ferocious dogs”, April 2024
