All dogs are good dogs, but some dogs are better at certain things.

Some are known for their hunting abilities, while others may be known for their agility or endearing good looks.

When it comes to pure explosive speed, however, the greyhound outpaces them all. Known as the "45-mph couch potato," the greyhound is a part-time speed-racer and part-time couch-surfers.

Mother Nature Network reports that at maximum acceleration a greyhound can reach 45 mph within its first six strides from a standing start, and can settle into a 35-mph pace for as long as seven miles at a time.