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Brachycephalic dog breeding

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Ratification Date: 13 Dec 2021

Policy

The paramount consideration in any continued breeding of brachycephalic dogs must be the welfare of the individual dogs and future generations.

Individual dogs must be given the best chance of living a healthy, pain-free life. To reduce the incidence of avoidable conditions that result in a lifetime of discomfort, any brachycephalic bitch or dog being considered for breeding should be assessed using phenotypic assessment and genetic testing, and only bred if they meet the recommended standard.

Background

There has been a recent surge in popularity of the brachycephalic dog breeds. Selective breeding over successive generations has resulted in phenotypic changes that cause genuine individual suffering and distress.

Continued selection for a dramatically shortened face has resulted in multiple anatomic changes which cause Brachycephalic Obstructive Airway Syndrome (BOAS), among other issues. BOAS affects the animal’s ability to breathe, exercise, thermoregulate, sleep, play and undertake other normal behaviours. Selective breeding in some brachycephalic breeds for the presence of a “corkscrew tail” (deformed vertebrae resulting in a twisted tail with reduced length) has resulted in a high incidence of vertebral body abnormalities including hemivertebrae. While there are many other heritable health issues associated with brachycephalic breeds, the AVA believes BOAS and vertebral body abnormalities are the two most severe and urgent issues that have the greatest negative impact upon the welfare of individual dogs.  This is why these two conditions are specifically addressed in this policy.

Of concern is that many owners taking on these breeds appear to be unaware of the likely health problems and the associated suffering these dogs endure, and the necessity to intervene surgically in many cases to improve quality of life.

The Five Freedoms are an internationally recognised framework that outline five aspects of animal welfare under human control. They are variously listed as: freedom from hunger or thirst; freedom from discomfort; freedom from pain, injury or disease; freedom to express normal behaviour; and freedom from fear or distress. It is arguable that the majority of brachycephalic individuals only live free from hunger or thirst if fed and watered sufficiently, however they enjoy none of the other freedoms.

Currently around Australia there are laws that could theoretically prevent breeding from many brachycephalic dogs, but these laws are not routinely enforced. For example, in Queensland the Animal Care and Protection (Code of Practice for Breeding of Dogs) and Other Legislation Amendment Regulation 2017 stipulates: “A person in charge of an undesexed dog displaying, or diagnosed with, a deleterious heritable condition must ensure the dog is not used for breeding, unless the person has written approval of a veterinary surgeon or a relevant geneticist” and lists brachycephalic syndrome as an example of a deleterious heritable condition.

In Victoria the Prevention of Cruelty to Animals Act 1986 makes it an offence to intentionally or recklessly allow an animal with a heritable defect to breed; however, the schedule of included diseases does not include brachycephaly, BOAS or vertebral body abnormalities.

Recommendations

  1. Dog owners taking on brachycephalic breeds must be fully informed of the health and welfare implications of BOAS and vertebral body abnormalities, including the potential costs associated with managing these disorders. These two health risks are so inherent in these breeds that educational material must be provided to the new owner at the point of accepting responsibility for the individual. The requirement for a breeder to truthfully disclose these health and welfare issues at hand over should be mandated in law.
  2. Individual brachycephalic dogs should be anaesthetised at an appropriate age and have their airways assessed for potential surgical correction by a suitably experienced veterinary surgeon. Airway pathology often described as “normal for the breed” is very often not “normal for a dog”. The quality of life for an individual dog with BOAS can often be dramatically increased by surgical correction. This surgery is not without considerable risk. Any dog undergoing BOAS surgery must not be used for breeding.
  3. Breeders must work to improve the phenotype of these breeds to reduce the incidence of BOAS and vertebral body abnormalities. Individuals must be selected for breeding on the basis of healthy airways and spinal columns. Champions at dog shows must be awarded for attributes that promote the health and wellbeing of the breed rather than the exaggerated “hypertype” features that are currently rewarded in the show-ring. It should be mandatory for dogs being shown to pass the screening tests outlined below.

To improve the health of extreme brachycephalic breeds as fast as possible, two initiatives should be undertaken:

  1. Cranial phenotypic screening: Dogs with a muzzle length less than a third of the skull length (the “craniofacial ratio” - CFR) must not be bred or shown.

In 2014, the Dutch government introduced new laws which provide a “traffic light” system for breeding of dogs. There are provisions to breed if one parent dog does not meet the CFR but meets five other criteria, but the other parent must meet CFR criteria. Meeting this requirement would allow for incremental improvement over successive generations. The Dutch rules should be adopted immediately by Australian Breed Societies, and the Australian government should consider making this scheme mandatory under legislation.

  1. Screening for vertebral body abnormalities: Reliable screening for vertebral body abnormalities should be established and affected individuals must not be bred or shown.

The presence of vertebral body abnormalities constitutes a significant health and welfare risk to individual affected animals. Vertebral body abnormalities have been shown to have a very high degree of heritability in all breeds, with a proven genetic link in French Bulldogs, English Bulldogs and Boston Terriers.1

In order to remove this genetic abnormality from the breeds the following methods of assessment are proposed:

  • Genetic testing: New research has presented evidence of a DVL2 gene defect associated with the presence of a “corkscrew tail”. English and French Bulldogs and Boston Terriers should be genetically tested and dogs with the defect must not be bred or shown. Dogs with a negative test may be used for breeding or showing, provided they also fulfil the cranial phenotypic guidelines in part A above.

The AVA encourages further research into the genetics of brachycephaly and vertebral body abnormalities and development of more commercial screening tests. As or when testing becomes available legislation should be introduced to make it mandatory prior to breeding susceptible dogs.

  • Phenotypic screening: Other brachycephalic breeds, or where no genetic testing is available, should be assessed with spinal imaging to see if they are suitable for breeding. Dogs should be a minimum of 12 months old at screening. Computed topography (CT) of the spine is the preferred and more accurate imaging modality but, if CT is not available, plain radiographs may suffice.2 Imaging must include the first cervical vertebra (C1) through to the most caudal vertebra including the entire tail.

Radiographs should be assessed by suitably qualified veterinary specialists with experience in vertebral body assessment. Individuals with any vertebral body abnormalities must not be bred. Only dogs found to be free of any vertebral anomalies should be used for breeding purposes or showing, provided they also fulfil the cranial phenotypic guidelines in part A above.

Gutierrez et al describe a radiographic classification scheme for vertebral malformations.3 For such screening schemes to be effective, they must require that only dogs found to be free of vertebral anomalies are used for breeding. 

Some breed clubs still allow ongoing breeding from dogs with positive scores for the presence of vertebral abnormalities.  For example, the French Bulldog club of NSW advise to “breed with care” any dog with a score over 15 (the median score for the breed in North America is 14). To put this in context, a partially-wedged vertebra will give a score of 1, a fully-wedged vertebra will give a score of 2, and a double-wedged vertebra will give a score of 3. The summation of deformed vertebrae gives the final score. This means the club is accepting the breeding of dogs with potentially up to 15 deformed vertebrae, or up to 5 significantly deformed vertebrae. Realistically, their recommendation allows perpetuation of the defect from generation to generation. 

Improvement will only be possible when dogs that carry the defect are eliminated from the breeding pool.

Other relevant policies and position statements

References

  1. Ryan R, Gutierrez-Quintana R, Ter Haar G, De Decker S (2017). Prevalence of thoracic vertebral malformations in French bulldogs, Pugs and English bulldogs with and without associated neurological deļ¬cits. The Veterinary Journal 221 25–29:
  2. Brocal J, De Decker S, José-López R, Guevar J, Ortega M, Parkin T, Ter Haar G, Gutierrez-Quintana R (2018). Evaluation of radiography as a screening method for detection and characterisation of congenital vertebral malformations in dogs. Veterinary Record doi: 10.1136/vr.104388
  3. Gutierrez-quintana R, Guevar J, Stalin C, Faller K, Yeamans C, Penderis J (2014). A proposed radiographic classification scheme for congenital thoracic vertebral malformations in brachycephalic “screw-tailed” dog breeds. Vet Radiol Ultrasound, Vol. 00, No. 0, 2014, pp 1–7.