I also wanted to point out that if the reason for aging a ferret is to decide if they can have surgery or not, that's best determined by a complete blood panel and organ screening. You can have a three year old with terrible liver and kidney functions who is unable to go through surgery but have a seven year old in perfect organ health who will go through a surgery with flying colors. I've heard too many people say "my ferret is too old for surgery." Yes, getting enough blood for a panel is not the most fun thing in the world, but it is so informative it is worth it. Laryssa [Posted in FML 5877]