So in the world of my upcoming campaign, gnolls are born when hyenas eat the corpses of creatures slain by Yeenoghu, who sometimes goes on rampages into the Material Plane. Gnolls who were once hyenas are savage and wild, but sometimes they have children normally to grow the horde. At least in my world, gnoll become more sentient and less evil murder beasts the farther removed they are from those original hyenas. So if a gnoll pup was born 5 or 6 generations removed from the original hyenas, they could conceivably become an adventurer. 

I was wondering if there were any preexisting versions of a race like this, or if anybody had any suggestions for making one.

Here's what I have so far:

ASI: +2 STR, +1 DEX

Rampage Trait, same as ordinary gnolls.

30 ft speed

60 ft darkvision

automatic Survival proficiency

Speaks Common and Gnoll