An item that lets the player disable damage to a chosen mob (survival)

What about an item which can be fed or provided to a mob that then prevents that mob from being damaged by player swings / attacks. This is mainly thought for dogs or horses when using them in battle, or even just avoid unfortunate accidents. Functionality wise, I figured have it work similar to the new golden dandelion which is toggleable by feeding the mob to enable the effect. Meaning you can undo it by repeating the action. For multiplayer, maybe have it so only the player who fed the mob the damage immunity item can benefit, which would mean in PVP you can avoid hitting your dog in combat, but the other player is still capable. This then means 2 or more players could feed the same mob this item and therefore disable damage from anyone who has interacted in this way.