His pet is always a level 15 White Tiger, the specific evolution varies, typically between Elder and Dire.
As you load into the zone, flag your heroes and henchmen (using the U map) to the spot just left of the bottom of the ramp where Salke Fur Friend Patrols. This takes about 30 seconds. Once your heroes and henchmen are in position run down the grassy hill to the opposite side of where they will be fighting. You'll see in your party tab that your H&H's have begun fighting with the boss. At this point you should be able to Charm the White Tiger with little to no interference as Salke will be tied up in battle.