What Is the Fastest Dog on Earth?

by Rebecca Bragg
The greyhound, the world's fastest dog, is a sighthound with a strong chasing instinct.


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At some stage in the 15,000-year-long partnership between dogs and people, someone noticed that dogs who keep their eyes on prey were capable of moving a lot faster than those who rely on their noses to track prey. When the hunters of ancient Greece and Rome switched from sniffers to "sighthounds," they found that they could get expend far less energy because they didn't have to run behind sniffing dogs -- they followed on horseback. The earliest known sighthound was bred by the Celts and is the ancestor of the fastest dog on four legs -- the greyhound.

Breed Origins

The once-widespread belief that greyhounds originated in ancient Egypt and the Middle East has been debunked by canine genome research conducted in 1997 and 2004 that clearly points to Celtic lineage, greyhound pedigree researcher Martin Roper asserts. A Greek text from around 100 B.C. mentions the speed of dogs bred by the Celts, a northern tribe, and exported throughout Europe as hunting, racing and guard dogs. Genetic studies have shown that the Vertragus, a Celtic dog with a Roman name, is the likely ancestor not only of the modern-day greyhound but also of a wide range of other European breeds. Some, like the whippet, have body shapes similar to that of the greyhound; others, like the St. Bernard, don't resemble them at all.


The saluki, an ancient breed also known as the Persian greyhound, gazelle hound and Arabian hound, was the royal dog of ancient Egypt and is still greatly prized by both nomadic and settled Arabs in the Middle East. Although the saluki resembles the greyhound, modern versions tend to be a little smaller, with longer fur and ears. Both are sighthounds, meaning that they rely not on scent but on sharp eyesight to run down their prey. From the little Italian greyhound to the huge Irish wolfhound, sighthounds come in a range of sizes and breeds but are built for speed, with long bodies and legs, broad chests and very little body fat.

Speed and Stride

The top speed of the world's fastest dog is 40 mph. when cheetahs, the world's fastest feline, are running full tilt, they can reach 65 mph. Since both animals are similar in size, physique and running style, why so large a gap? To find out, researchers at the U.K.'s Royal Veterinary College tested racing greyhounds and captive cheetahs but immediately encountered a problem: The dogs were faster than the cheetahs. Attributing this to lack of motivation among animals that had never hunted for food, the researchers took it on faith that cheetahs can outrun greyhounds, concluding that the cats' strides get longer as they accelerate, while the dogs maintain the same length of stride no matter what their speed. The study was published in June, 2012 in the "Journal of Experimental Biology."

Greyhound Racing

Public interest in the sport of greyhound racing, banned outright in seven states, is on the decline and according to the U.S. Humane Society, as of mid-2013, only 46 racetracks in 15 states still existed. Much of the reason for this downturn is controversy over the way the dogs are treated. Every year, surplus breeding to ensure the availability of animals with the greatest aptitude for racing takes place while adult racing greyhounds, which would ordinarily have a life expectancy of 13 years, are retired before they reach the age of 4. Greyhound rescue organizations strive to find good homes for unwanted puppies and retirees but many end up being destroyed. The ASPCA cites the Greyhound Network News and the Greyhound Protection League's report that an estimated 19,000 industry-bred greyhounds were destroyed in 2000. Of those, about two-fifths were litter culls and three-fifths were retirees with no available homes.

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