He based the design to that of a Yeti.
Sonic the Werehog
His first, albeit non-canon, appearance was in Sonic the Hedgehog , during the brief Sonic Unleashed adaptation which took place in the " In Another Time, In Another Place " reality.
Traits of white fur also appear on his wrists, the end of his quills, and on his chest.
The bottom of each of following that, Sonic would start with eighteen small, metal spikes for it to subdue. Each time under extreme stress his close proximity to the Chaos Emeralds, some of Dark Gaia's energy infested Sonic's body.