bird that's how Guild Wars does it pretty much. If you choose "Ranger" as a Primary/Secondary class, you gain a "Tame Animal" spell that can be used on wild animals, i.e: Lynx, Tiger, Boar, Moa Bird. I myself have a level 20 Boar
It works well, and as rangers are usually a low-hp high-damage range class, the pet works well to distract enemies away from you - the line is, how powerful is the pet. That's where the work needs to be done. Goooooooood Morning Vietnaaamm!