As a Birman breeder of 20 years standing I can advise on this quite well. I can quote you the Summary from research done at Bristol and Edinburgh Universities by Dr Danielle Gunn-Moore.

Summary:

This study suggests that many Birman cats may have some degree of renal dysfunction, which may or may not result in signs of ill-health, and which may or may not progress with time. It has not yet been possible to determine an underlying cause of disease in clinically affected cats, nor to draw any firm conclusions as to the nature of the defect within the breed as a whole. While the clinical significance of these findings therefore remains unclear, it seems appropriate to suggest that evidence of elevated kidney enzymes in an otherwise healthy Birman cat should not be over interpreted as evidence of severe or progressive disease. It would however, seem sensible to monitor affected cats, and to consider the possibility of renal dysfunction when undertaking anaesthesia, surgery or treatment in cats of this breed.

OK, now the real day to day facts. Some Birmans have a tendency to small kidneys BUT they are rather unique in the fact that they seem to be able to tolerate the elevated urea levels much more than any other cat. If the cat has its annual boosters then the vet can give them their MOT and sometimes by the fact that the vet has picked up the smaller kidneys, they tend to scare the owners into thinking their cat is about to go into renal failure. In the majority of cases this is not the case. My own vet is now very clued up on it where others may even go as far as suggesting euthanaesia.

My first Birman started showing signs of renal problems at the age of 11 but with the proper treatment lived on to the good age of 17.5 years old. She had small kidneys all her life so this should show that it is possible to still have a long living cat. On the other hand my moggie showed signs at the age of 9 and only lived to the age of 11. I think that demonstrates the stamina that Birmans actually do have in this respect.

My kitten owners are all told about this as I have no wish for a vet to get euthanaesia happy. I currently have a 14.5 year old whose urea level is within the normal range and is still going to shows so just because someone cites a breed as having a problem, doesn't mean they all will.

Every breed has its own problems as you only have to substitute any breed name for Birman in your searches.

Marcia