You can obtain this hunt as soon as you reach Mt Bur-Omisace for the very first time. You should make an effort to complete this hunt before traveling up to the temple at the top of Mt Bur-Omisace and while you still have Larsa as a guest in your party.
Hymms is a blue human character standing near the Chocobo Stables near the Save Crystal at Mt Bur-Omisace.
You can find the Feral Retriever in an area of the Paramina Rift called the Spine of the Icewyrm. Warp to Mt Bur-Omisace and purchase the map of the Paramina Rift from the Moogle from the Cartographer’s Guild to help you find the location.
Travel south through the Freezing Gorge into an area called the Frozen Brook. Take the southernmost exit into the Path of the Firstfall area and then south into the Spine of the Icewyrm. The Feral Retriever is located very close to the entrance to this zone.
Level: 28
HP: 22,559
Steal: 
Pebble, Quality Pelt, Prime Pelt
By the time you receive this petition and can take down this Mark (after the first visit to Mt Bur-Omisace), the Hunt is fairly easy, especially if you have completed a few of the other Hunts.
The only thing that you really need to watch for is the Feral Retriever’s excessive use of negative status effects such as Petrify, Sleep, Slow, Silence and Blind. 
Esuna can be used to cure most of these effects, so setup a proper Gambit on one or more of your characters to take care of this, and create another Gambit to use 
Gold Needle items on any characters who are hit with the Petrify status effect.
You can also use the 
Nihopalaoa trick to inflict Disease, Confuse, Reverse, Slow, Immobilize, Silence and Blind on the Mark making the fight significantly easier. Equip your characters with accessories to prevent some of the status effects.
A video of the battle in the Zodiac Age version is included below:
Return to Hymms at Mt Bur-Omisace to complete the Hunt. The reward for defeating the Feral Retriever is 1,500 gil, a 
Recurve Crossbow and two Teleport Stones.
