Cats in Trouble: The Burmese Breed 

Dr.Douglas Schar



The Burmese breed was created with two imported Thai Mutation cats, Wong Mau and Tai Mau.  There is evidence that other imported Thai Mutation cats were used to support the early breeding program.  The genetic diversity of these imported foundation cats resulted in a young breed with great genetic diversity. However, after 80 years of continuous inbreeding, that genetic diversity is gone.  


Recent genetic research determined that the American Burmese breed is one of the two most inbred group of cats on the planet. 

In the article, The Ascent of Cat Breeds: Genetic Evaluations of Breeds and Worldwide Random Bred Populations ( Genomics 2008 January, 91(1):12-21) the Burmese breed got the unfortunate distinction of being one of the most inbreed purebred cats. “The Burmese and Singapura breeds have the lowest heterozygosity and the highest FIS of any breed, reflecting the most intense in- breeding...given these results, Burmese breeders and Singapura breeders should be concerned about genetic diversity,”


Tragically, this finding is not theoretical. Burmese breeders across the United States are experiencing the real life implications of inbreeding, including reduction in adult physical size, reduction in litter size, reduction in litter survival rates, reduction in immune function, and lethal deformities.  


Inbreeding Depression 

All pure bred animals, be that a cow or a cat, are inbred to an extent. But, when inbreeding continues for too long, and the gene pool becomes too small, something known as “inbreeding depression” occurs. Signs of inbreeding depression include reduction in vigor, fitness, fertility, litter size, litter survival, and increased incidents of lethal and sublethal genetic disorders. If the inbreeding continues, it terminates in the EXTINCTION of the population of animals in question. 


Inbreeding, inbreeding depression and extinction Lucy I. Wright,  Tom Tregenza David J. Hosken, University of Exeter, (2007).


The Burmese breed is displaying the classic signs and symptoms of inbreeding depression. What breeders fail to realize is that inbreeding depression is more like a cliff than a gentle downward slope. One day, without prior notification, you just drop off the cliff. Suddenly, most cats wont get pregnant, most kittens wont survive, and the ones that do, will be crippled, deformed, and unable to breed. Inbreeding depression is a serious threat to the continuation of any breed and it needs to be taken seriously. Once you fall off the cliff, its virtually impossible to come back from it.


There is still time to reverse the inbreeding depression in the Burmese breed. However, action must be taken immediately. Amongst Burmese breeders, some do not comprehend the severity of the problem, and others do.  It is a very mixed bag. It would be fair to say there is no concerted effort on the part of breeders in general, or the main registry organizations, to address the problem. 


The Bad News 

When I interviewed Burmese cat breeders, from around America, I discovered most are not concerned about the inbreeding problem. They do not see it as a serious threat. 


However, when I questioned the unconcerned breeders. looking for signs of inbreeding depression in their lines of cats, I always found them. Whether they understand the significance of the signs or not, they are very much present.


Indeed, on the Cat Fanciers of America website, in the Burmese breed section, one article about the breed is provided for breeders and the general public.  The article, “The Joy of Burmese”, written by Erika Graf-Webster, includes the following statement, 


“Contrary to the belief of some, the Burmese breed is not suffering from an unusually small or very restricted gene pool. An early result of the Feline Genome Project currently being done by the National Cancer Institute was the finding that the Burmese breed appears to have plenty of genetic diversity. There is no danger of the breed becoming frail or endangered due to an inbred, small gene pool. Burmese are healthy and sturdy cats, with many living well into their late teens.” 


This article, and its existence on the leading purebred cat registries website, accurately depicts the state of play in the community of Burmese breeders.  The problem of inbreeding depression is denied, is not being taken seriously, or  its signs and potential consequences are poorly understood. 


The Cat Fanciers of America Burmese Breed Council did adopt a policy that would allow breeders to outcross Burmese cats to Tonkinese cats, Bombay cats, and Cats from Southeast Asia. 


Considering the American Tonkinese and the Bombay breeds were created using American Burmese cats as their foundation stock, these breeds are not the best option when it comes to adding genetic diversity to the breed. Unless fighting fire with gasoline makes sense. 

However, the “Out-cross to Imported Southeast Asian Cats and Foundation Burmese Policy”, adopted in January, 2011, does offer a real solution. Unfortunately the CFA and the Burmese Breed Council are making it difficult for anyone to import, register, and use breeding stock from Thailand. 


I have spoken to several individuals, willing to import cats from Thailand, at great expense to themselves. Without any exception, they have reported the CFA and the Burmese Breed Council to be unresponsive. When the interested parties contacted these organizations regarding importing cats from South East Asia, it came to nothing. They were either given the run around or their requests for information or assistance were simply ignored.  A policy has been adopted, but, the parties meant to implement it are not doing so. 


The Good News 

There are a handful of breeders who are working to integrate new genetics into the breed.  One such breeder is Nancy Reaves. Ms. Reaves bred a recently imported female Tong Daeng type cat, Mod Daeng, and is now working with her offspring. She is distributing kittens with these new genes to other breeders. To my knowledge, Mod Daeng is the only cat that has been imported from Thailand for the purpose of shoring up the breed genetic shortfall.  




More Bad News 

Overall, it can be said that most of the Burmese breeders in America are not concerned about the Burmese inbreeding problem. In addition, the organizations responsible for the quality control of the breeds, appear equally disinterested in doing anything about the problem.  

In my experience, looking the other way, when inbreeding depression is afoot, is a prescription for disaster. 


Firstly, I have first hand experience with inbreeding depression. There as a time when I worked with heritage breeds of chickens, ducks, and turkeys. In example, while breeding silver Ameraucanas, a color type of a blue egg laying chicken, I first encountered it. From one generation to the next, fertility stopped. The birds stopped mating, hens laid less than four eggs a month, and the few eggs that were laid were usually not fertile.  Attempts at outcrossing were in vain. The roosters and the hens were sterile. The flock died out.   


In my opinion, being medically trained, the most dangerous consequence of inbreeding depression is the poor immune function that associates with it.  Inbred animals have shoddy immune systems. 


More specifically, being so closely related to one another, all members of the breed tend to have the same immunological weak spots. In effect, they have the same immune system. All it takes is one virus, or one bacteria, for which the breed cannot mount an effective immune response, and catastrophic losses can be expected. 


Lack of immune function, when you are keeping animals in groups, is a disaster. While working with the Blue Slate heritage turkey’s, we hit the point of inbreeding depression. Sadly, the flock became infected with a bacterial infection which could not be cleared with antibiotics. All of the birds became infected, none of the birds were resistant to the bacteria, and none of the birds survived. 


Depending on too few genes being a disaster is not a theory, it is a matter of history. 


In the last century, the Irish people depended upon a handful of related potato varieties. When a blight came along, all of the potatoes were affected and a total crop failure resulted. None of the potatoes were resistant to the blight, and all the potatoes died. Millions starved, millions emigrated. The Irish potato famine, and its catastrophic consequences, remains a constant reminder that genetic diversity is good, lack of genetic diversity is bad. This was true with potatoes 120 years ago, and it is true with Burmese cats today. 


The Solution 

The good news is there is a simple way to fix the problem.  Breeders simply need to infuse the Burmese breed with new, unrelated genetics. They need to outcross their cats to unrelated cats.  The question becomes, what cats would be the best cats to use in this outcrossing? 

One straight forward way to do this is as follows. Re-create the breeding experiment used by Thomson, 80 years ago to create the Burmese breed. Use the “Burmese” cats that result from the repeated “experiment” to add genetic diversity to the breed. The descendants of that original experiment provided enough genetic diversity to keep the breed going for almost 100 years, and if conducted again, the result will be the same. 


Selection Cats for the Burmese Experiment: Part Two 

It is true that genetic diversity needs to be returned to the Burmese breed. And, there has been some efforts on the parts of the governing bodies to make that possible. Some provisions, however poorly enacted, have been made for outcrossing. However, I feel that the provisions that have been made miss the mark. 


The adopted CFA policy that allows for outcrossing to Tonkinese, Bombay, and cats from South East Asia that conform to Burmese colors, sable, blue, champagne, and platinum. The policy is all about color. The kittens that are born out of these outcrosses must conform to accepted Burmese coat colors. 


Nowhere in the outcross policy does it mention, in my opinion, the most important trait possessed by the Burmese breed. Personality and disposition.  


I am obsessed with Burmese cats because of their fantastic personalities. I keep them because of the incredible companionship they provide. They are the dog minus the walk. I keep Burmese cats because they are singularly, the most wonderful pet a person can have. I do not keep them because of their coat color, I keep them because they are fantastic pets.  

When we talk about saving the Burmese breed from the brink of extinction, one has to ask the question, why bother? Why is the breed worth saving? Is it because they come in nice colors? 


As far as this breeder is concerned, the breed is worth saving because Burmese cats behave like no other cat. If the breed disappears or so does the opportunity to have one of the most wonderful cat that has ever been. The loss of Burmese cats, and the unique personalities and dispositions, would be an enormous loss to the quality of my life and the quality of life of many others.  


I will work to infuse the breed with much needed new genetics. I will do so by running the breeding experiment Thompson ran almost 100 years ago.  But, I intend to do so with a view to maintaining the most important feature of the breed,  the Burmese personality and disposition.  



Create an approximate cat to Wong Mau. 

In Thompson’s experiments, when two hybrid cats (Tong Daeng type cat x  Wichienmaat type cat) were bred, the breedings litters resulted in light Tong Daeng, Dark Tong Daeng, and Wichienmaat type kittens. Wong Mau was a light Tong Daeng type. In addition, we know that Wong Mau and Tai Mau carried Korat genetics because their breeding produced Korat type cats. 


Breed imported Wichienmaat male to imported Korat female. Select a kitten from that breeding with a friendly disposition. This breeding may result in kittens that are phenotypically black or phenotypically Wichienmat, but genetically(W x K)

Breed  Burmese sable male to (W x K) female. This will produce kittens that are phenotypically Korat, light Tong Daeng, and Wichienmaat but genetically B x (W x K). It will produce Wong Mau 2. 
Recreate the Thompson experiment using Wong Mau 2 and an imported Wichienmaat type cat. This breeding will produce Tong Daeng type cats and Wichienmaat type cats. 


Breed Wong Mau 2 back to a son that displays the dark Tong Daeng characteristics. Distribute these kittens to breeders in America.