Nothin' But a Hound Dog

 is a quest in Fallout: New Vegas.

Quick walkthrough

 * Talk to Julie Farkas about what can be done to help Rex.
 * Return to the King with the news that Rex can be healed.
 * Take Rex to Doctor Henry in Jacobstown to learn how he can be fixed.
 * Acquire a new brain for Rex from one of Old Lady's Gibson's dogs.
 * Rey's Brain increase Rex's attack.
 * (Optional) Search for an exceptional canine brain among Caesar's Legion.
 * Lupa's Brain increases Rex's durability.
 * (Optional) Search for an exceptional canine brain among the Fiends.
 * Violeeta's Brain increase Rex's speed.

Behind the Scenes
This quest is a reference to the Elvis song of the same name.