You can also just put a bear trap in the area wolves spawn in.
They catch medium animals from the area they are placed in every day.
Just take your live wolf, pur it in the right size fence/cage, feed it a few live chickens and/or bunnies, and there you go.
You can also catch small animals like bunnies and chickens with the small traps. They also catch some every day for free.
I usually have 5 or so bear traps in the wolves area in case I want some, and a few in the blue grass area to catch some sheeps easily. It helps to get cabbage seeds without warping in and out of the area until you finally find some...