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.

Detailed Walkthrough
Talk to King (the leader of the kings) in Freeside. ask him bout Rex he will tell you that something is wrong with Rex. He also tells you to go to Julie Farkes. Julie Farkes will be in the Old Mormon fort. she will tell you that there is a man Dr. Henry in Jacobstown who can help. After that you must tell King that his dog can be fixed. He allows you to take Rex to Dr. Henry. After, you go to Jacobstown you will find that Jacobstown is a super mutant town. He will tell you to to find at least 1 dog brain for Rex. The first brain you need is at Old Lady's Gibson's dogs. She will ask you for 700 caps, if your barter skill is at 70 it will be less. The second brain will be at a Fiend camp near Vault 3, there are two sections to the camp, one is a type of kitchen with Cook-Cook at the leader, in the other section of the camp is a structure built from ruined buses, this section is populated by Fiend Guard Dogs, Violetia, a boss Guard Dog and a hound master called Violet, you can aquire Violet's head after killing her and you can aquire Violetias brain after killing it. Choosing to implant Rey's brain will give Rex a perk to increase attack damage, Choosing to implant Violetta's brain will give Rex a perk to increase speed.

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