An ancient European tale of Atam and Eue, when Adam and Eve first get to earth they’re both quite stressed and under duress, after coming through the Tree-portal. They didn’t know where they were or where God was, and as you can imagine, they wanted to get home. God had given Adam a special raiment, a garment of skins which allowed Adam to converse with the animals. Adam then asked the dog to help them find their way home.

Based on this, and the story about the dog finding them first it makes sense that "dog is man’s best friend." (Being it was the first animal mankind encountered on Earth and it tried to assist Adam and Eve) The dog valiantly tried to help Adam and Eve to get home. He sniffed and searched for their trail but kept losing it, so he eventually had to give up. God had brought them through the tree portal and there was no way getting back until the appointed time, as mentioned in the early prophecy of man’s time on earth and his destiny of defeating the snake.