French Bulldog Genetic Action Plan [FBGAP] – Stage 1  

Gene Variant DVL2 [The Screw Tail Gene] and Gene Variant AdamTS3 [Airways Oedema Gene]

Gene Variant DVL2 [The Screw Tail Gene]

Brachycephalic breeds may carry genes which can alter the state of their tail to have a corkscrew or curled effect. The gene variant responsible for the short curly tail is called variant DVL2, more commonly called the Screw Tail Gene. Sadly, there is a cost to the dog for that cute short tail because if they have this gene, it can cause serious adverse health side effects.

The serious condition caused by this gene is called Hemivertebrae [HV] which causes malformed spinal bones and other brachycephalic complications. In dogs that are affected by the Screw Tail gene (they have 2 copies of the gene) their vertebrae can have an odd shape that may cause the whole spinal column to twist.

If those odd shaped bones are confined to the tail, the twisting may not affect the dog’s spine in any significant way. But if the deformed hemivertebrae bones are in the main part of the dog’s spine, the twisting can put pressure on the spinal nerves that lie within the column of vertebrae and may result in neurological problems for the dog.

This congenital abnormality of the vertebrae which are seen in brachycephalic breeds commonly affect two areas:

1. Defects in the thoracic (chest) vertebrae which doesn’t usually result in severe spinal cord deviation or narrowing, nor does it appear to be a cause of major problems in later life; and
2. Defects in the lumbar area where, if there is a definite kinking or twisting on the spine, is more likely to have detrimental effects on the caudal spinal cord of the puppy as it develops.

Radiography can give information on the presence of spinal abnormalities, but it can’t predict whether those abnormalities will affect the function of the spinal cord. Also problematic, is reliance on radiography results showing limited or even no sign of HV as there is no guarantee that this dog’s puppies will also have a good spine.

This is why the MDBA started our Brachycephalic Breed Genetic Action Plan – [FBGAP]. We want our breeder members to select against this gene in their brachycephalic breeding programs to ensure we have the healthiest brachycephalic breeds possible.

Initial results in our BBGAP program with the Screw Tail gene substantiates previous studies that show that dogs with the DVL2 gene carry additional risks for brachycephalic obstructive airway syndrome [BOAS] and congenital heart defects.

Gene Variant AdamTS3 [Airways Oedema Gene]

Respiratory problems are common in a number of dog breeds and it is especially common for short-nosed breeds to have trouble breathing. Swelling of the airways makes this problem worse.

One of the MDBA’s strategies to deal with breathing problems for brachycephalic breeds is testing for the AdamTS3 gene, more commonly called the Airways Oedema gene. The Gene Variant AdamTS3 is a gene that contributes to breathing difficulties by causing swelling (oedema) in the airways. It is most commonly found in British bulldogs, French bulldogs and Norwich terriers. It has also been found more rarely in other breeds.

The airways of dogs with two copies of this gene can be more significantly impacted compared to dogs with one copy or no copies of this gene.

As part of the MDBA Brachycephalic Breeds Genetic Action Plans we are calling on all MDBA Breeder members who have the following breeds to DNA test for the DVL2 gene variant [Screw Tail Gene] and the AdamTS3 gene Variant [ Airways Oedema Gene]

• French Bulldog
• British Bulldog
• Boston Terrier
• Australian Bulldog
• Staffordshire Bull Terrier
• American Staffordshire Terriers

It is important that we know the status of all dogs in these breeds in our gene pools. We strongly advise our breeder members with these breeds to test for these two genes and to seek out and use dogs with only one copy or no copies of these genes in their breeding programs.

DNA Testing for these genes in Australia, is now available in one place via Dr Kao Castle from Dog Breeding Science with good turnaround with an MDBA discount here https://breeding.dog/index.php?test=scr&org=MDBA

References

1. Canine DVL2 variant contributes to brachycephalic phenotype and caudal vertebral anomalies https://link.springer.com/article/10.1007/s00439-021-02261-8 https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007850
2. Guevar J, Penderis J, Faller K, Yeamans C, Stalin C, Gutierrez-Quintana R. Computer-assisted radiographic calculation of spinal curvature in brachycephalic “Screw-Tailed” dog breeds with congenital thoracic vertebral malformations: reliability and clinical evaluation. PLoS ONE. 2014;9:e106957. doi: 10.1371/journal.pone.0106957. - DOI - PMC - PubMed
3. Mansour TA, Lucot K, Konopelski SE, Dickinson PJ, Sturges BK, Vernau KL, Choi S, Stern JA, Thomasy SM, Döring S, Verstraete FJM, Johnson EG, York D, Rebhun RB, Ho HH, Brown CT, Bannasch DL. Whole genome variant association across 100 dogs identifies a frame shift mutation in DISHEVELLED 2 which contributes to Robinow-like syndrome in Bulldogs and related screw tail dog breeds. PLoS Genet. 2018;14:e1007850. doi: 10.1371/journal.pgen.1007850. - DOI - PMC - PubMed
4. Moissonnier P, Gossot P, Scotti S. Thoracic kyphosis associated with hemivertebra. Vet Surg. 2011;40:1029–1032. doi: 10.1111/j.1532-950X.2011.00876.x. - DOI - PubMed
5. Oechtering G, Schlüter C, Lippert J. Brachycephaly in dog and cat: a “human induced” obstruction of the upper airways. Pneumologie. 2010;64:450–452. doi: 10.1055/s-0030-1255513. - DOI - PubMed
6. Packer RM, Tivers MS. Strategies for the management and prevention of conformation-related respiratory disorders in brachycephalic dogs. Veterinary Med (Auckland) 2015;6:219–232. doi: 10.2147/VMRR.S60475. - DOI - PMC - PubMed
7. Ryan R, Gutierrez-Quintana R, ter Haar G, De Decker S. Prevalence of thoracic vertebral malformations in French bulldogs, Pugs and English bulldogs with and without associated neurological deficits. Vet J. 2017;221:25–29. doi: 10.1016/j.tvjl.2017.01.018. - DOI - PubMed
8. Airways Oedema AdamTS3 https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1008102