Googe translations, as other software based translations, are prone to being very clumsy because they are inclined to slip into transliteration but often (mostly) the meaning nevertheless comes through if you use your imagination. On the other hand, guessing leaves you wondering if you really have the correct interpretation. Your sentence is possibly removed from significant context that imparts some further nuance but it speaks of dogs with a guard dog instinct having given good results when in the care of those who have the will, ability and knowledge to handle them.