TICA Khao Manee Breed Committee Report

2 Sep

Written and compiled by Janet Poulsen, Chrissy Russell and Jen Lacey

KHAO MANEE BREEDING POLICY
GENETICS OF THE BREED AND ADVICE FOR BREEDERS

1: Statement of purpose of the Breeding Policy & background of the breed

This breeding policy is intended to give advice and guidance to new breeders of Khao Manees as more cats are imported and kittens are bred and sold for breeding. Health will be of paramount importance, and second to that will be the objective of selecting of Khao Manees to work towards the proposed Breed Standard which defines the ideal for a showbench specimen of the breed.
It is written as a statement of best practice. However, with the breed in its infancy in western cat fancies, and for which history, legend and myth are a fairly seamless blend in its native country, it’s recognised that there will have to be periodic revision as more becomes learned and understood about this white cat of Thailand. It is good that we have the support of Dr Leslie Lyons and her team at UC Davis for projects concerning white cats and  deafness and breed genetic diversity.  The roots and origins of the Khao Manee are parallel (and probably intertwined) with the other historic breeds from that part of the world: the Siamese Seal Point, Korat and Burmese. The Khao Manee (also known as the Khao Plort) is one of the breeds in the famous book of cat poems (Tamra Mao) which was produced at least as far back as 1350 and is a national treasure today. The four above mentioned are the most famous of about 17 breeds listed as lucky cats and represented their country on sets of stamps produced in 1971 and 1995. It is surprising that when the other three have become well established in the west it isn’t until very recently that the Khao Manee has arrived here, but it’s believed it has a natural place alongside the other ancient Thai breeds and so deserves recognition and preservation.

2: Selection for breeding
Although selective breeding has just begun, it is not imagined that it will be too difficult to fix and maintain type in the Khao Manee. The head and body shape are of medium size, ears medium to slightly large and the eyes are not required to dominate the face. This is a cat of no extremes, and although the odd-eyed is most prized in its native country the decision was taken not to place emphasis on this as it could restrict a gene pool which will be small in number and only increased by importation. Lines should not be excluded to aim for a very small number of a specified eye color. What is essential is that breeders select healthy cats as foundation stock and maintain the solid build and muscular appearance that is called for. It’s known that gradual loss of size and more delicate appearance in future generations could be an indicator of inbreeding depression. Because of the small number of imports initially there will be close monitoring of this factor. Due to their early limited genetic base, the TICA Breed Committee will recommend to its breeders that the size, health and temperament should always be checked in prospective parents as the main priorities. Selection will also be made by pedigree checks to avoid the repetition of common ancestors. A Pawpeds data base is being established, but as yet too few ancestors are known to give sufficient generations for meaningful inbreeding coefficients. However, Prof Bateson’s advice will be firmly kept in mind, “Avoid very close inbreeding. A good rule of thumb is that if the pedigrees of the potential mates include more than two (common) grandparents,
avoid that mating.”(“Independent Inquiry into Dog Breeding” – Sir Patrick Bateson FRS)

3: Genetic Makeup of the Breed
All cats have 19 pairs of chromosomes upon which there are many genes that govern the eventual  shape, size, sex, color, pattern and hair length of the individual animal. Over the generations a number of mutations have occurred and selective breeding has been used to isolate these to produce the various pedigree breeds we see today. White which, with its geographic origin and short coat, defines the Khao Manee as a breed, would have been one of the early ones as it is found in the domestic populations throughout the world. However,
unlike in other species, including people, in cats it is very rarely associated with albinism. Like the White Persian, White British Shorthair or Foreign White the Khao Manee is a cat wearing a white overcoat. Dominant White (or correctly ‘epistatic white’ since it occurs on a different gene from the black or red based colors) is denoted by the gene symbol W. W cats do not have the pale blue/pink light sensitive eyes of the albino (cc), nor the nystagmus that is associated with this. Some kittens are born with a ‘cap’ (hairs on top of the head) of a
different color, some have been born without the white overcoat, indicating that the parents are Ww, with the offspring inheriting the recessive (w) from both parents.

4: White cats and deafness
There is an established link in cats between the white coat color, blue eyes and deafness.  The tapetum lucidum is generated from the same stem cells as melanocytes (pigment cells).  The blue eyes of an epistatic white cat indicate a lack of tapetum. Deafness is caused by an  absence of a cell layer in the inner ear that originates from these same stem cells as well. They fade out progressively in the first week or so after birth. However, although research has ascertained that more white blue eyed cats are deaf than white non-blue eyed cats, not all
blue eyed cats are deaf and not all white non-blue eyed are hearing. Odd eyed cats, like some Khao Manees, may be deaf on one side (usually the side with the blue eye) but not all are. So appearance (phenotype) is not a definite indicator of deafness. It is going to depend on genotype, the genes that the cat has inherited, and as yet the particular complex of genes governing deafness has not been identified, though work is ongoing at UC Davis and Baltimore. At present there no scientific proof to back the statement made by Sarah Hartnell in her
summary on white/cat deafness research: “other types of blue eye are being discovered in all-white cats in Asia, the blue is different from Siamese Blue Eyes, but does not seem to cause deafness”, it remains conjecture, but there is some anecdotal evidence from Khao Manee breeders in the west who are keeping records that the deafness is not occurring at the same frequency as it does in European originating blue eyed breeds. White x white matings have been accepted practice in Thailand and, although the use of the non-standard colored Khao Manees is accepted in the registration policy, to ensure no exclusion of otherwise healthy cats of good type and new to the genepool, white x white is very highly advised.. Research to date (University of Baltimore, where there is an established colony of white cats, some blue eyed, others not) has shown an increased risk of deafness in the progeny if both parents are blue eyed, but not a distinction dependent on homozygosity/heterozygosity for W. So from
knowledge to date the rationale for Khao Manee breeders is the premise that as dominant white is a complete dominant gene with no additive effect in its homozygous state (no proof existing that homozygous whites are more likely to be deaf than heterozygous whites) breeding white to white gives the opportunity to selectively breed to influence the polygenes against deafness, whereas random polygenes of non-white cats may skew away  from the direction of the selective breeding. Time and research results will give further information. In the meantime the proposed TICA breeding policy for the Khao Manee will advise strongly against the breeding of deaf cats.. Also this breeding policy strongly advises against the mating of blue eyed cat to blue eyed cat. A blue eyed cat may be used for breeding but should have a non-blue eyed or odd eyed partner. On what is known to date these strategies should reduce risk of deafness occurring.

Notes:
A) Careful note will be taken of new research on white cats and deafness produced by veterinary medical faculties, and this policy will be revised according to recommended best practice based on such results.
B) The TICA Khao Manee Breed Committee will keep a record of Khao Manee kittens born. It is recommended that a cat that produces deaf offspring on two occasions with different partners is no longer used for breeding (unless participating in a study directed by veterinary/genetic counselling).

5: Other issues
It is known that skin cancer may affect any cat with white ears, including domestics.  Breeders will be advised to give new owners information of its possible occurrence and the necessity for the use of suitable sun block products.
As yet no other genetic problems are known to have occurred in the Khao Manee, but of course it is impossible to say they never will, only to reiterate that it will be essential to keep records and breeders will be encouraged so share information for the good of the breed as a whole. There has been a very high percentage of cats with kinked tails amongst the cats imported from Thailand. It is recognised that this a common trait in cats from that part of world. Since the Written Thai Standards that we have seen for the Khao Manee all mention that the tail should be long, yet rather minor tail kinks that do not substantially shorten the tail are not seen as faults in it’s native land, we feel that breeders should not, at least at this time, select only for straight tails. As it has no major
impact on health and welfare, breeders are recommended initially to focus on genetic diversity (eg  not all going to the only male with the straight tail) yet avoid selecting for tails that are significantly shortened. Records are being kept and sent to Dr. Leslie Lyons Lab along with DNA swabs regarding hearing status, tail kink status, eye color, kitten “cap,” and homozygosity/heterozygosity when known. We are also keeping photographic records of offspring, noting white spotting patterns on ww nonstandard colored kittens.

6: Genetic Diversity
At present Dr Lyons is collecting Khao Manee samples to produce a genetic diversity score and the cats imported to the USA and to the UK have contributed DNA. Records are being kept and conveyed to Dr. Leslie Lyons Lab along with DNA swabs from each kitten born regarding hearing status, tail kink status, eye color, kitten “cap,” suspected genetically influenced disease, and homozygosity/heterozygosity when known. We are also keeping photographic records of offspring, noting white spotting patterns on ww non-standard colored kittens. This section will be further developed once results have been produced.
There are no plans as yet to outcross the Khao Manee with any other breed. The intention is to maintain diversity by import. If this became impossible for any reason, and/or Khao Manee breeders were advised by veterinary/genetic counseling that out-crossing was needed to maintain/improve breed health, then the breeds that would be considered are Thailand’s other natural cats, the Korats and Thais. This policy would be revised to include advice for breeders if such an eventuality ever occurred

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