Ok, I've seen alot of hunter posts about mounting with ur pet, demounting and the pet will have full health.
This has never worked for me unless im mounted in the correct amount of time it takes for my pet to regen naturally.
Instead as your running around you can just put ur pet on stay and when he gets too far away he will dissapear.
Call him and he will have full health!
This is great if your being attacked by many mobs. Just Mend Pet, Feign death, have your pet attack all of them, Put cheetah on and run until pets out of range.