Initially, German Pinschers were bred to become working dogs, hunting and killing vermin. And until today, these dogs will still hunt down these animals, making them unfit for pet rodent owners. On the good side, the German Pinscher maintained their "working dog" energy. They do well in a lot of careers and dog sports. While many German Pinschers excel in conformation sports, obedience, tracking, and agility trials, others can be seen as therapy dogs, service dogs, and family companions.
Take note, though, that they may be overbearing and assertive at times, taking over not only your heart but also the house. Needless to say, they are not recommended to inexperienced owners. They need firm, consistent owners who can establish rules and keep up with their training needs. So if you prefer placid dogs, it will be best if you find another breed.