The term 'DOG PART' can be solved by the four-letter word 'TAIL'. A dog's TAIL is an extension of its spine and is used for balance, communication, and other functions. Dogs use their tails to express a variety of emotions, such as happiness, excitement, and fear. The TAIL also serves as a rudder when a dog is running or swimming. In some breeds, the TAIL is docked, meaning it is cut off at the base. This practice is controversial and is not recommended by many veterinarians.