I've got even more feedback from aspiring veterinarians out there. Here's the new list (somewhat rearranged):

• The 'grizzly method' only seem to work until the high 20's.
• Even a near-dead dragon can be healed with veterinary in the mid 20's, without failure and without gain.
• By using the method described in the skill gain essays, but replacing grizzly bears with brown bears, you can get to 58 before it really starts to slow down. At this point you can start to attempt curing poison for gain.
• You can get to at least 82 by curing poison.
• Curing poison don't seem to give gain in the low 90's even if it is deadly or beyond.
• Pets that has been verified to use the seemingly bugged percentage system to heal are dragons, white wyrms, drakes, grizzly bears and lava lizards.
• Animals that use the old '# of hitpoint lost' system include brown bears and small ice snakes.

Leafbeach