Fido's Friend is a term used to describe the four most common canine companions. ROVER, VET, SPOT, and REX are all names that can be used to refer to these four-legged friends. ROVER is a five-letter name that is often used to refer to a dog, VET is a three-letter name that is short for veterinarian, SPOT is a four-letter name that is often used to refer to a puppy, and REX is a three-letter name that is often used to refer to a large breed of dog. All of these names are commonly used to refer to Fido's Friend.