Running Catch Dogs

more than likely many of these traits evolved through selection of the winners and not a conscious selection for these particular traits...winners are/were the ultimate truth as to what should be bred...and the facts that are known now about what makes a great racing hound have been studied after those facts...winners are made through proper selection out of racing winners, better breeding practices, training and diet etc...
racing dogs are bred for just that and of course breeding for other work requires a certain amount similarities yet very different type of dogs...

the information below I copied from a website...

Due to the Greyhound's unique physiology and anatomy, a veterinarian who understands the issues relevant to the breed is generally needed when the dogs need treatment, particularly when anesthesia is required. Greyhounds cannot metabolize barbiturate-based anesthesia as other breeds can because they have lower amounts of oxidative enzymes in their livers.[36] Greyhounds demonstrate unusual blood chemistry, which can be misread by veterinarians not familiar with the breed; this can result in an incorrect diagnosis.[37] [3]

Greyhounds are very sensitive to insecticides.[38] Many vets do not recommend the use of flea collars or flea spray on Greyhounds if it is a pyrethrin-based product. (See Dog fleas.) Products like Advantage, Frontline, Lufenuron, and Amitraz are safe for use on Greyhounds and are very effective in controlling fleas and ticks.[39]

Illustration of the Greyhound skeleton
Greyhounds also have higher levels of red blood cells than other breeds. Since red blood cells carry oxygen to the muscles, this higher level allows the hound to move larger quantities of oxygen faster from the lungs to the muscles.[40] Conversely, Greyhounds have lower levels of platelets than other breeds.[41] Veterinary blood services often use Greyhounds as universal blood donors.[42]

Greyhounds do not have undercoats and thus are less likely to trigger dog allergies in humans (they are sometimes incorrectly referred to as "hypoallergenic"). The lack of an undercoat, coupled with a general lack of body fat, also makes Greyhounds more susceptible to extreme temperatures (both hot and cold); because of this, they must be housed inside.[43]

Anatomy[edit]

The key to the speed of a Greyhound can be found in its light but muscular build, large heart, and highest percentage of fast-twitch muscle of any breed,[44][45] the double suspension gallop and the extreme flexibility of the spine. "Double suspension rotary gallop" describes the fastest running gait of the Greyhound in which all four feet are free from the ground in two phases, contracted and extended, during each full stride.[46]