Worlds fastest dog. 1  It was difficult to determine which the fastest dogs are, but since the first book of Guinness World Records released, we can track these records easily. In 1994 a record was set - the English Greyhound named Star tight showed a speed of 67.32 kilometers per hour and became the fastest dog in the world. Billions of dollars are spent every year on Greyhound races, but this record still stands. To this day the English Greyhound, is a world leader in terms of speed.