I'm considering spending some wizard tokens on zapping one of my pets. I know it can zap your items in your inventory/minions into dust, but can it also effect the items in your pets treasure chest?

The treasure chest isn't in danger, I never heard about anyone who lost tc items while zapping. C:

Great. thanks for your answer ^^

The only thing zapping will do to your treasure chest is increase the size. Items in it are perfectly safe.