Classic TV - Tales of Tomorrow - "The Miraculous Serum" (1952)

A physician invents a serum allowing animals to overcome any illness or injury, by magnifying their adaptability. He tests it on an impoverished young woman, who's moments from death. Becoming healthier than she's ever been, she thanks him for "giving her the world," which for her is much more than a figure of speech.
https://www.imdb.com/title/tt0717076/plotsummary?ref_=tt_ov_pl

This video is in the Public Domain.