For his Luon Highway roll, Domri will have the fortune of running into a Reptile Egg. After a few days, it will hatch into a Rattler Boa- around the size of his forearm at first but will rapidly grow if cared for properly.

Unfortunately, during Quest-time, it doesn't seem like any eggs are able to be found in Mekiv Caverns. It's quite possible that all the recent commotion has chased away any breeding beasts out of the area for a short while.