The term "sheep dog" is commonly used to refer to a breed of dog that is skilled in herding and guarding sheep. However, there are numerous other synonyms that can be used to refer to these dogs. For example, you could refer to them as pastoral dogs, working dogs, or livestock guardians. Some specific breeds of sheep dog include the Border Collie, the Australian Cattle Dog, and the Old English Sheepdog. Regardless of what you choose to call them, these dogs play a vital role in helping to manage and protect flocks of sheep, and are valued for their intelligence, loyalty, and work ethic.