I have taught my american molossus to guard my tortoise. If Binkey ever wanders off without my dogs watch(Brutus) you best believe Brutus will find him. My dog can search for him on 3 acres and find him relatively easy. Yesterday was one of those days that took an hour to find the tortoise but my dog found him without fail. My dog loves this and thinks its a fun game we play, the highlight of his day is waking up to go greet his brother Binkey.