How to Breed Sensibly with
DNA Tests
French Bulldog Clubs should look at any DNA test that is specific to the French Bulldog with regard to the numbers affected, the severity of the disease concerned, the impact on the animals health and well being and decide whether any animals need to be removed from the gene pool. Many breeders erroneously consider that affected dogs cannot be used. But the beauty of having a DNA test is that, in the main, no animal needs to be lost to the gene pool.
Club members need to understand a) how these diseases are inherited; b) how to sensibly use this information; and c) not lose any valuable breeding stock unnecessarily.
The vast majority of DNA tests currently available (>90%) deal with simple recessive diseases.
SIMPLE RECESSIVE DNA DISEASES – POSSIBLE MATINGS
Normal/clear dogs are shown as ‘AA’
Carriers (heterozygous) are shown as ‘Aa’
Affected dogs are shown as ‘aa’
Where ‘A’ = normal dominant allele and ‘a’ = affected recessive allele. One allele comes from each parent.
As ‘A’ in this case is a dominant normal gene, all un-highlighted matings are acceptable.
Matings highlighted in red are not advised and should not occur.
Matings highlighted in pink are high risk but may be required from time to time. If done, all progeny should be DNA tested prior to sale.
There is 1 reasonably significant DNA disease test available to the French Bulldog at this time, which is largely being underutilised. There are also tests for colour dilution, mainly for blue, but as this is not considered a major issue by many, it is less frequently tested (or used as a selection criteria for breeding). More tests are constantly being developed. Some of these may cover obscure diseases, while others may cover significant diseases within the breed.
HC (hereditary cataract) HSF4 gene—this is an early onset cataract disease, usually affecting both eyes which is seen within the first 2-3 years of life and is progressive (ie. they go blind). These cataracts can be removed surgically, which is expensive, but the dog should have reasonable vision afterwards. This condition can be tested and the affect, carrier and normal dogs readily sorted out.
Cataracts occur in many breeds, some are early onset, some are late. The incidence in the French Bulldog does not appear to be high in Australia. However the consequences of a young dog going blind where this can be avoided, should have breeders test for this condition when doing genetic profiles.
DM (degenerative myelopathy) is a disease that occurs at the other end of a dog’s life. There are no confirmed cases of DM worldwide in the French Bulldog up to this point. I do not recommend testing for DM in the French Bulldog. DM is a very old gene that is widespread in the canine population and turns up in many breeds (over 120 I believe at last count) as well as cross bred dogs, yet only 17 breeds have been proven to develop the disease – of which the French Bulldog is not included. There are obviously other mitigating factors that turn these dogs from “at risk” to affected that are not present in these unaffected breeds.
The number of cases of DM and HC are under reported. Use of the Health Report can assist us in ensuring we are improving the overall health of the breed as well as giving us more accurate statistics.
SNIP tests—when DNA testing SNIP tests are now available that will test all known (and recognised) diseases in any breed. These will also test for parentage (where generational data exists). It is now cheaper to test this way than for individual disease testing. Current costing is around $60-65 for 1 disease and around $135 for 3-4 diseases plus parentage.
Dr Karen Hedberg BVSc
2020
Find more information about DNA
Click here for a sitewide search
