Due to the health problems brachycephalic breeds may suffer, the Bulldog Club of America, French Bull Dog Club of America, and Pug Dog Club of America successfully urged the Orthopedic Foundation for Animals (OFA) to license the Respiratory Function Grading Scheme (RFGS) from The Kennel Club in the United Kingdom/University of Cambridge for use in the United States and Canada.
Brachycephalic breeds have been bred to have increasingly flatter faces as the characteristic is considered like that of a ‘cute’ human infant. For years, we have known that this exaggeration of features leads to brachycephalic obstructive airway syndrome (BOAS), which can include one or many of the following conditions: stenotic nares (narrowed nostrils); elongated soft palate (excess length partially blocks the entrance to the trachea); laryngeal collapse; tracheal hypoplasia; extended nasopharyngeal turbinates (long thin bones in the nose to direct air flow); and, everted laryngeal saccules (pouches).
We know there is a genetic component. For instance, almost 92% of brachycephalic dog chromosomes have the SMOC2 LINE-1 insertion compared to only 2% of non-brachycephalic dog chromosomes. Other insertions, deletions, mutations, and variations of the gene pool are more than likely also involved. The DNA changes causing BOAS are complex. Remember, a dog can have one or more of the aforementioned health conditions to cause BOAS.
Figuring out the complete genetics of BOAS will take time, which those breeds most afflicted by the progressive disease do not have. We urgently need to move the anatomy of these breeds in the right direction to lessen the health burden of BOAS.
Dogs are graded on a 4-point scale and should be assessed every two years during their breeding years. Grade 0 means that the companion dog is clinically unaffected or has not yet developed symptoms of BOAS. A grade of 1 requires a dog to be clinically unaffected but has some mild respiratory signs. Grade 2 equates to a dog that is now clinically affected and has moderate respiratory signs of BOAS. Grade 3 entails clinically affected dogs with severe signs of distress.
Since BOAS is genetic and progressive, when should breeds known to develop brachycephaly be bred initially? Oftentimes, we say two years old, and both the sire and the dam should be graded a few weeks prior to breeding.
If both dogs are Grade 0 or 1, the grading states they can be bred together. A Grade 2 dog (either sex) can be bred with a Grade 0 or 1 dog. Two Grade 2s really should not be paired. Dogs with a grade of 3 should not be bred whatsoever, no matter the grade of the mate. Honestly, breeding a dam diagnosed with Grade 3 would be cruel and inhumane.
How does a companion dog get a grade? The health screening consists of four steps: a short health survey, a brief physical examination while the dog is calm, a brisk 3-minute walk, and evaluating the respiratory system post-exercise.
The UK Kennel Club is so transparent about its grading scheme that it might appear that anyone may be permitted to assess a companion dog, which is incorrect. One requirement to receive a certified grade is that a specially trained veterinarian has to perform the examination. Additionally, the training is in-person shadowing and no plans are on deck for virtual training. (This is a good decision.)
Will this work? We hope so. Breeder participation is voluntary. Breeders bear the responsibility for responsible breeding practices. Companion pet caregivers bear the responsibility to not only know about a breed’s potentially inherited conditions, but also about all of the available genetic tests and assessments for these conditions. Caregiver knowledge can be imparted from research or breeder transparency education.
How does a companion pet caregiver verify the results? The assessor (trained veterinarian) submits the grade to OFA or The Kennel Club in the U.K. If it is a grade of 0 or 1, this is added to the breeding dog’s public profile, along with the date of the exam and the age of the dog at the time of the exam. A grade of 2 or 3 is only publicly available if the breeder allows it.
Due to the progressive nature of BOAS, we have several scenarios to consider. Let’s say a dog is two years of age, receives a Grade 0, is bred, and then has a disease grade of 3 at the assessment two years later. What do we do? Granted, the probability of this particular possibility is very low. By contrast, a degeneration from Grade 1 to Grade 2 is quite likely.
While disease progression to a Grade 2 or 3 will remove the public health assessment score (unless breeder authorized), we assume the dog will still be listed if previously used for breeding.
Please remember that breeders who have dogs diagnosed with a Grade 2 or 3 can still decide to breed those particular dogs. As we stated previously, breeding a Grade 3 dog in our view is inhumane. Breeders should be following responsible pet breeding practices. While many breeders do what’s right, some may not. A companion pet caregiver should be aware of the scoring system and ask the breeder for grade history if none is listed on the OFA or The Kennel Club websites.
What do we do about the litters of dogs with grade changes from 0 or 1 to 2 or 3? Currently, the breeder can choose to divulge the change to the forever homes of the dogs.
What is the frequency of the grade changes over time? OFA and The Kennel Club are tracking the data. Since the program is brand new in the U.S. and relatively new in the U.K., more data are needed to answer this question. Moreover, more data are needed to make any assessment or policy changes based on this question. Then, the individual clubs and breeders will need to work it out.
We see this standardization as creating positive changes such as: weeding out the genes that can cause a very debilitating, painful and lifelong illness; reducing the symptoms of BOAS; and, awareness.
References
Dodds, W. Jean. “Breeding Brachycephalic Dogs and Cats, Part 1.” Hemopet, 11 Mar. 2022, https://hemopet.org/breeding-brachycephalic-dogs-and-cats-part-1/.
Dodds, W. Jean. “Breeding Brachycephalic Dogs and Cats, Part 2.” Hemopet, 18 Mar. 2022, https://hemopet.org/2909-2/.
Ekenstedt, K J et al. “Canine Brachycephaly: Anatomy, Pathology, Genetics and Welfare.” Journal of comparative pathology vol. 176 (2020): 109-115, doi:10.1016/j.jcpa.2020.02.008, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380493/.
Lederhouse, Coco. “Health screening test rolled out for brachycephalic dog breeds.” American Veterinary Medical Association, 30 Jan. 2023, https://www.avma.org/news/health-screening-test-rolled-out-brachycephalic-dog-breeds.