Some of them know more commands than others. They'll usually say on their info card.
It actually is dependent on how they came a lot of them have some basic knowledge because they are ones that lost families and where others do not. You have to ask or read the cards to find out. I still recommend visiting with the pet you've decided at least more than oncetp bring home.
Some are, you just have to ask, or go visit with the pets...
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