GodThingFormerly
A Different Kind of Asshole
McCoy quits Starfleet for a civilian practice of some kind - the unfilmed part of the script has him treating children AND tame lions and such!
Not at all. McCoy is (re)introduced treating the injured paw of some children's tame pet cheetah in Harold Livingston's teleplay for the Phase II pilot, In Thy Image (which formed the basis of ST:TMP), although this and other character/plot elements can be traced back to Gene Roddenberry's script for The God Thing:
"Scotty has become an alcoholic, and McCoy has given up treating human patients to become a veterinarian, loudly proclaiming animals as the only sensible patients he has ever had." - GR as quoted in Starlog Magazine (#3, January, 1977).
...outdated novelization...

TGT