In many parts of the world, the dog -- any dog -- is man's best friend. However, in Spain, an ancient breed of hunting dog called galgos are being horrifically abused; thousands are killed, and many more are abandoned.

According to a report from National Geographic, the galgos used to be bred exclusively by the nobles in Spain. Insiders say they are known to be loyal, kind, affectionate, and "sassy."

"They're great dogs," Colorado's Galgo Rescue International Network (GRIN) founder Abigail Christman said. "They're a greyhound with a sense of humor. They're a little more fiery, a little more sassy."

Perhaps it is due to this sassiness combined with the loyalty and intelligence of the breed that galgos are chosen by galgueros (breeders) for hare and lure coursing, controversial sports where the dogs released on a track to speed after either hares or mechanical lures.

Coursing is practiced in other parts of the world, but breeding and training of galgos are industries that tend to be terribly abusive to animals in Spain. Mass breeding are prevalent, and many of the dogs are forced to live pitifully: chained in tiny bunkers and barely fed.

"We've had galgueros that have had 70, 120 galgos, living on crisps and bread and eating each other when they die," Christman revealed.

Galgueros train the dogs to be faster by tying a pack of 12 to 15 of them to a motorbike or car and forcing them to run, getting a lot of them injured or dead. But it's not just training that's killing galgos by bulk. Those who are not up to the breeders' standards are slaughtered after one or two hunting seasons.

About 50,000 to 100,000 dogs die annually of this tradition, albeit in different ways. Some were thrown down wells or tossed in rivers, while others are burned or killed with acid. There have been canines abandoned in forests with legs broken and even an occasion when one was found with a pin hammer on their skull. Hanging is also regularly practiced, especially for competitors who are no longer performing well.

It's hard to catch and prosecute galgueros violating the national laws of animal cruelty, in part because it's so difficult to spot them red-handed doing the crime.

Tina Solera of Galgos del Sol said that their ongoing operations of rescue are not long-term. Public education remains the biggest hope for these dogs. The organization aims to spread the word on galgos welfare through social media and other forms of promotions, but they also go straight to the galgueros to encourage humane treatment.