THE HEALTH OF OUR BREED
It is up to us to make informed, educated choices
Creating Genetic Diversity
In 2018 Khayama cattery welcomed a new breeding female: STARKATZ ACORN, out of an American Burmese and in 2019 another lovely brown, STARKATZ MISS EFFIE.
Why? The national gene pool has continued to narrow. Smaller litters, unexplained cat and kitten losses, smaller cats, shorter lives, and a litany of health problems are becoming the norm. Breeders and registering bodies are in denial and problems remain a hidden catastrophe for the breed. It has become impossible to find a pedigree without duplication and most catteries do not allow outside use of their studs.
Line breeding (read "inbreeding") has been the accepted way of breeding since the 70's when the breed came into this country. This cannot continue and the effects are now obvious. We must replace inbreeding with careful selection of type.
Feline geneticist Associate Professor Leslie A. Lyons, PhD, University of Missouri is highly respected throughout the world by other geneticists, veterinarians and breeders alike. She warned "if the Burmese were a wild breed, they would be extinct by now". She has called for the careful outcrossing of the Burmese. This is echoed by other geneticists, including Langford, UK, and many veterinary surgeons.
In 'Genetic Notes on the Burmese Cat Breed' 2016, Dr Lyons wrote: “. . various genetic studies have repeatedly demonstrated that Burmese, regardless of country, have amongst the lowest genetic diversity of all cat breeds” .....“Burmese breeders may consider crossing the Burmese cats from different countries to help improve genetic diversity.”
Since the research done by Professor Leslie A. Lyons there has been a growing movement worldwide to save the breed - unfortunately this has not been taken up or encouraged in Australia.
In 2017 Bev Jones of NSW Starkatz Cattery (http://starkatz.com/) took the courageous step to import 2 American Burmese females.
American Burmese imported into Australia must be tested negative for known genetic problems: Hypokalaemia, GM2 and Cranial Facial Defect.
Their progeny must be kept on a separate register (unlike the rest of the world).
Still people worry that the imports will bring in some unwanted genes – these cats are probably tested for more inherited defects than the local cats & hence are potentially safer (read 'healthier') than Australian bred Burmese.
I quote Bev: “Thanks to our myopic registries, our Burmese friends invariably form an exclusive pool. No matter how large our longstanding this pool has become – our national pool is by no means diverse. The resultant genetic loading can only represent the difference between our fittest genotype and the average fitness of our entire population. This diversity level has narrowed over time with the overall average diversity really only heading one way – down. This means our average fitness standing (overall health vigour and ability) can only remain stable or deteriorate. A decade ago one might have claimed our Burmese were holding their own. The evidence more recently; smaller litter sizes, increased neonatal death, increased rates of flat chests, higher frequency of genetic diseases or impaired immunity, suggests otherwise. This evidence is very much pointing to a deteriorating pool of genes.”
Briefly, a homozygous brown Burmese has following genotype: aa cbcb BB DD ii
a = non agouti, A = agouti, ie a solid coloured coat
cb = Burmese gene
B = black (the brown Burmese is genetically a black cat, but the burmese gene cb changes the black colour to a brown colour)
D = dense gene - allele for non-dilution, full pigmentation
i = non silver
American Burmese and European Burmese and Australian Burmese all have this same genotype (ie nothing but Burmese). Different countries select for a slightly different type. Cats imported into Australia are selected for type that will best suit the Australian show standard.
Below are photos of some of our wonderful Khayama kittens produced with the addition of American lines - note the Burmese type & eye colour . Unfortunately these Cats & kittens cannot yet be shown next to "Australian" Burmese within the Feline Assoc even though they have exactly the same genotype.
Avoiding the American Burmese Head Defect through Genetic Testing
Many years ago (late 1970s) American Burmese males were bred to accentuate a rounded and shortened head to produce a style of cat with a shortened face. Known as brachycephaly, offspring from such a mating became vulnerable to defects of the craniofacial surface. The American Burmese head defect is the result of an autosomal recessive genetic mutation that affects Burmese offspring during the second trimester of pregnancy, and with unpredictable outcomes.
The good news for Australian Breeders is that imported animals are tested to prevent the condition from ever occurring. A genetic test exists which can accurately identify that an imported animal is not a carrier. Moreover, the test is inexpensive and easily arranged through UC Davis Laboratories. It involves a simple swab of saliva taken by using a household cotton swab and wiping over the gums and teeth of a candidate animal. The swab can then be processed and produce results via e-mail within 5 to 10 working days. The test confirms no head defect condition exists.
In Australia, Burmese breeders should be aware but not alarmed. The importing of American Burmese, or any other Burmese for that matter, is intended to solve the problem of inbreeding and breed diversity. It is not to perpetuate unfortunate myths around European versus USA bloodlines or to exacerbate a dichotomy between different breeding cat factions. Breeders and their Breeding programs should always use the basis of facts to influence their choices of bloodlines and standards. Well-being will simply follow.