Pets with leprosy

My favorite pet angel of mortifer seems to have contracted leprosy which is killing him/her slowly. how do i get my pets cured of leprosy? i tried getting it to drink a potion of antidote liquid but it doesnt seem to want to do that.

throw a bottle of antidote at them and then retame them.

more elaborate method.
Take their weapons if they are more dangerous than you. Get in a narrow passageway with diseased pet on one side and enemy that kicks on the other (eg unicorn, humanoid/golem with no arms) drop bottle of antidote on ground. hope enemy kicks it and it splashes favourite diseased pet.

And to explain the angel's behaviour - monsters with standard AI don't drink or eat if they're satiated or if they don't use nutrition. Angels fall into the latter category.

If I leave the angel behind in attnam will it go feral or dissapear? it was given to me by saccing so i believe it is permanent

It'll be fine. Might be easier to keep track of its location in the cellar though.