For some reason i always thought you could use tix on a retired animal.. turns out you can't. But... i think players would like to be able to use tix on a retired animal, I know I sure would! 

-bump-

Good morning binx! I know this suggestion has been brought up multiple times in the past, and it has always been a no go. I believe this is due to the fact of it leveling the playing field for all players to have the same amount of time to train animals to their highest.