WOW, cats that live to 20 and 23.
My leroy passed after he had lived with me 20 years. He was a stray so in his mid 20's vet said.
Kelcee will be 17 on May 5th. About a year ago, vet said she would'nt last a yr. She is still with us. She probably won't make it to 20, but is living the good life now.
She might have what you call 'a' tremor, or sort of a 'tick'. Vet noticed it also, but didn't say what he thought it was.
Katz