Snowball, Princess, "Puss", "The Cat"... many names, one cat.
This is a picture of my cat, taken a few weeks before she had to be put down.
I now know she had a condition called PKD - Polycystic Kidney Disease.
It causes the cat's kidneys to degenerate, usually at 6 - 8 years of age.
There is no cure.

Cat breeders have to be very careful to ensure they are not breeding from animals that carry the disease if it is to be eliminated.