Generally refers to your close friends and enemies. The breed of the dog you see in your dream not only expresses the power and struggle with your enemy or rivals, but also gives information about the character of the enemy or friend. Since a friendly dog is a close friend, a large dog indicates great friendship while a small dog indicates a more distant friendship.
To take a walk with a dog in your dream is interpreted as you will take a ride or have an adventure with your close friend. If the dog you have seen in a dream first approached friendly but showed her/his teeth later, it means that a friend will turn his back on you and show hostile attitudes.