pf2e.fyi
From Pathfinder #177: Burning Tundra, which isn't enabled.

Megafauna Veterinarian

FEAT 6
Archetype Mammoth Lord
Prerequisites Mammoth Lord Dedication; Expert in Nature

By heeding the wise advice of elders in your following- and aided by your own experience-you've learned how to provide medical care to the megafauna of the Mammoth Lord followings. You can attempt a Nature check instead of a Medicine check for any of Medicine's trained and untrained uses, provided the subject of your medical care is a megafauna. If you're attempting an action that requires a particular proficiency rank in Medicine (such as Treat Wounds), use your proficiency rank in Nature instead. If the subject of your care is your megafauna and you roll a success on your check, you get a critical success instead.

Pathfinder #177: Burning TundraOGL