LASTNIGHT I NOTICED THAT MY SIAMESE (AGE 12) LOOKS AS IF SHE HAS LOST 1/2 HER BODY WEIGHT AND IS HAVING TROUBLE SITTING, SHE SHOWS NO OTHER SIGNS OF ILLNESS, WHAT COULD BE CAUSING THIS RAPID WEIGHT LOSS?
She did not loose the weight in one night. This was probably more gradual. Weight loss is a clinical sign to almost all cat diseases. I can not speculate. I recommend a visit to the vet for some tests. vetcare