Oriental Shorthair Cat - this photo by .m for matthijs was added by Michael to show the breed. There is no connection between this cat and the article.
I was informed of Hepatic Amyloidosis in Siamese & Oriental Cats by a visitor (Lisa Lyons) to this website who lives with beautiful Oriental Shorthair cats. You can see her post here: Owned By Two Oriental Shorthair Cats. I had not heard of this disease despite building a page on Genetic Diseases in Purebred Cats some time ago.
Lisa thought that it was pretty rare in Oriental Shorthair cats. Apparently it also affects Siamese cats, which is unsurprising as they are one and the same cat almost, the Oriental being a "modern" Siamese that has a much wider coat colour and pattern range.
I am not sure how prevalent it is amongst these two breeds; and lets remember that the Siamese is a very popular cat breed.
A site dedicated to this disease (link below) informs us that although we are not sure how commonplace it is, the author of the site feels that it is " fairly widespread". The point she makes is that breeders breed from the same bloodlines (same original cats). On this basis it is likely to be fairly widespread I would have thought.
It is often misdiagnosed and has been in existence for about 30 years.
What are the symptoms?.
The symptoms of Hepatic Amyloidosis in Siamese & Oriental Cats include: feeling ill, pale gums, pale ears, slight jaundice (yellow skin and eyes), high white cell count, low red cell count, vomiting frothy bloody fluid, the disease may wax and wane, come and go.
Amyloid cysts damage the liver causing it to bleed. The cat dies quickly. This can produce an incorrect diagnosis but a biopsy shows blood in the abdominal cavity.
The disease is incurable and fatal. Some cats die within 2-3 years.
What is being done?
Research into genetics as this is an inherited disease. A gene marker is being searched for to understand how the disease works and how it can be cured.
Cat owners who suspect that their cats have the disease should go to
this website -- link broken May 2013--- and follow the instructions at the base of the page. This will help in the long term to control and eventually eliminate this nasty disease.
Other information - source: Merck Veterinary Manual
The disease also affects Abyssinian cats and a dog breed, Chinese Shar-Peis. The disease generally leads to hepatic disease (liver disease) as mentioned above.
Another condition associated with Hepatic Amyloidosis in Siamese & Oriental Cats is hypervitaminosis A. Other signs are anorexia (weight loss), polydipsia (excessive thirst), and polyuria (the passage of large volumes of urine), vomiting, icterus (jaundice as mentioned above), and hepatomegaly (an enlarged liver).