Progressive Retinal Atrophy or P.R.A what is it and do I need to test my cats?????
The quick answer is that it progressive retinal atrophy is a hereditary disease that is thought to cause blindness in Siamese cats. The theory is that the gene responsible needs to be passed on from both parents to cause blindness. In other words an affected cat would need genes passed on from both parents and would be homozygous for the P.R.A gene. If a cat carries just one copy of the gene responsible and is heterozygous for the gene then it is thought they are not at risk of blindness themselves. Of course they remain carriers and have a fifty percent chance of passing on the gene to any of their own kittens.
We hope that after reading the article below and viewing further information on the websites suggested you will be able to make an informed decision about testing your cats for P.R.A.
What is PRA or Progressive Retinal Atrophy
There is a genetic disease that is being seen more frequently in the Siamese and related breeds, this is Progressive Retinal Atrophy or P.R.A. The theory being that a cat that is homozygous for this trait will most likely be blind by the age of 3 to 5 years. Some research shows the 33% of Siamese and their related breeds are carriers, and 11% are affected. This is a worrying thought as it will not be long before the disease is more deeply entrenched in the breeds.
Fortunately there is a genetic test available from either UC Davis in California or at Langford in Bristol, the test at Langford costs about £25 if you are a member of a breed society, (they can issue discount codes to members) a small price to pay for piece of mind. This enables breeders to make informed breeding decisions about matings, hopefully with this genetic information we can selectively breed to eradicate this disease from our cats.
Further information on P.R.A is available from these sites:-
Langford Veterinary Services
La Voix Cats Blog
Editors notes –
It is interesting to note that anecdotal evidence from U.K Siamese cat breeders and owners show no evidence of blindness being rife in Siamese cats. However there is evidence of P.R.A positive cats going blind in their senior years.
It is also interesting to note that there have been cases of cats testing positive for progressive retinal atrophy. These cats being homozygous for progressive retinal atrophy which means they posses the P.R.A gene from both their parents. These cats have been 8 and 9 years old and have not been blind! However there are also reports of cats as old as 12 beginning to go blind and when tested they are found to be P.R.A positive.
It is probably safe to say that testing for P.R.A works. It is also probably okay to say that perhaps scientists are only just beginning to understand the gene and how it causes blindness in cats. Testing and research is in the early stages.
It would be foolish to discount the fact that there does appear to be some connection between P.R.A positive cats and blindness. It would be equally foolish to panic and neuter all our positive breeding cats just because they are P.R.A positive.
For now though until further research gains and understanding of progressive retinal atrophy it would seem sensible to continue to test our cats and not breed two carriers together. This would eliminate the chances of homozygous P.R.A cats and equally help to minimise the amount of heterozygous P.R.A positive cats in the gene pool.
Since publishing this article the team at Siamese Cat Breeder have been contacted by people who have cats that have been diagnosed with progressive retinal atrophy and have been tested to confirm they are indeed PRA positive. We were asked to help expand on this article to raise awareness. You can find a much more in depth article about PRA in Siamese cats here.