Board Thread:The Quarters - Q & A/@comment-24.210.33.169-20140305195408/@comment-24459124-20140305203923

It's simply hatching potions hatch eggs. In the case of the Wolf Egg, if you use a Desert potion, you get a Desert Wolf. A zombie potion yields a Zombie Wolf.

If you look at the Pets page, you'll see that there's a large tabular display of all the potential basic animals, and they are all the combinations of Eggs + Hatching Potions. Thus, simply, all potions can be applied to all eggs.