British Bulldog Genetics Explained: ADAMTS3, Inheritance, and Breeding in Australia

ADAMTS3 copy number variation was identified as an important genetic marker associated with airway oedema risk in British Bulldogs by Marchant et al (2019, PLOS Genetics), who described it as associated with upper airway syndrome. The finding broadened the understanding of the breed's breathing: not simply an inevitable consequence of conformation, but a measurable genetic variable with a copy number that can be tested and considered in breeding decisions over time.

Copy number 0, 1, or 2. A 0-copy result means no copies of the tested ADAMTS3 risk allele were detected. A 1-copy result means one copy of the tested risk allele was detected. A 2-copy result means two copies of the tested risk allele were detected and, under this marker, represents the highest inherited risk category. ADAMTS3 status is one piece of information that informs breeding decisions; it does not by itself predict an individual dog's breathing outcome, which is shaped by structure, function, fitness, body condition and management.

ADAMTS3 testing from cord tissue — collected at the time of delivery — provides the earliest and cleanest sample available. Buccal swabs can be taken later. For a buyer assessing which puppy to choose from a litter, or for a breeder building a program, the copy number of every individual in that litter is one important piece of information the documentation should record alongside structure and whole-dog assessment.

When a zero-copy male is mated with any female — regardless of whether she carries zero, one, or two copies — no puppy in that litter can receive more than one copy. A zero-copy male mated with a one-copy female produces a litter where each puppy is either zero-copy or one-copy, in equal proportion. A zero-copy male mated with a two-copy female produces a litter of all one-copy puppies. No puppy inherits the two-copy outcome when one parent is zero-copy.

Most British Bulldog breeding pairs in Australia today are both one-copy dogs. From a 1×1 pairing, the expected litter distribution is 25% zero-copy, 50% one-copy, and 25% two-copy. That distribution is an expected value — individual litters vary — but across a program, the proportion of each copy number in the offspring population reflects the pairing decisions made.

Pairing decisions that include at least one zero-copy parent lower the average copy number across a program. A zero-copy stud is one effective lever a breeder using an outside male can use to avoid two-copy offspring from that mating. These inheritance patterns describe ADAMTS3 results only; they do not on their own predict how an individual puppy will breathe, which depends on structure, function and whole-dog factors.

Genetic testing for ADAMTS3 copy number is conducted by laboratories equipped for veterinary copy number variant analysis. Dog Breeding Science — DBS — is an Australian veterinary genetics laboratory based at 40 Boronia Street, Redfern NSW. The laboratory reports the puppy's ADAMTS3 result as 0, 1 or 2 copies of the tested risk allele.

At Hollywood Bulldogs AUS, cord tissue is collected at delivery by the attending veterinary team as part of the program's established collection process. Professional veterinary services are engaged on a fee-for-service basis. Cord tissue collected at delivery provides an early and clean sample for copy number analysis; results are then recorded against each individual puppy once laboratory testing has been completed.

A documented program records parent results, puppy results, collection method and laboratory records as part of its normal breeding process. For the puppy you are considering, or for the dogs your program has produced, that documentation forms part of the wider whole-dog picture alongside structural and functional assessment.

For a buyer, understanding that a breeder produces Triple Carrier dogs means the colour range of any given litter is predictable from the genetics of both parents. Rare colours are not random outcomes — they are the result of pairing decisions that account for which colour modifier genes each parent carries. A breeder who tests for colour genetics can tell you, before the mating, which colour combinations are and are not possible from that pair.

For a breeder using a semen purchase from an outside stud, the stud's colour genetics determine which colour outcomes are possible in the resulting litter. A Triple Carrier stud opens colour possibilities that a stud without those modifier genes cannot produce, regardless of the female's colour genetics. When evaluating a semen purchase, the stud's ADAMTS3 copy number and his colour genotype are both relevant variables — and both can be confirmed from documentation before the decision is made.

The direction of a program is visible in what it has produced. Hollywood Bulldogs AUS — MDBA registered, member #18715 — has documented Australia's first 1-copy female, Australia's second 1-copy male, and Australia's first 0-copy British Bulldog males. Hollywood Bulldogs AUS holds Australia's largest collection of ADAMTS3-tested 0-copy and 1-copy British Bulldogs. These milestones describe ADAMTS3 results and are one part of the wider breeding picture, which also includes structure, function and whole-dog assessment.

Fresh, chilled, and frozen semen from ADAMTS3-tested Hollywood Bulldogs AUS studs — including 0-copy males — is available to breeders Australia-wide. A pairing using a 0-copy Hollywood Bulldogs AUS stud avoids the two-copy outcome from that litter regardless of the female's copy number. For a breeder whose program currently relies on 1-copy or 2-copy dogs, a documented pairing with a 0-copy stud is one direct step available to influence the copy number distribution of your program's next generation.

The goal of the Breeding Brachys for Health program is not to remove carrier dogs from the breed — that would reduce genetic diversity. It is to document every pairing and support a downward trend in copy number across the population over time. For a buyer evaluating which puppy to choose, or a breeder deciding which pairing to make, ADAMTS3 information is one important tool — not the whole picture — and sits alongside structure, function and whole-dog assessment.