Greyhounds are commonly accepted as the fastest dogs in the world, but other breeds, such as salukis and border collies, are close in speed. Over very long distances, the Alaskan husky is probably the fastest dog in the world.
Fit racing greyhounds can reach speeds of 45 miles per hour over short distances. According to Christine Zink, DVM, as quoted in Vetstreet, border collies participating in sports like flyball often reach similar speeds. Salukis can reach similar speeds and can sustain them longer due to their heavily padded feet, which act as shock absorbers. Alaskan huskies can only run at about 28 miles per hour, but they can maintain a relatively high rate of speed for hours.