It's a 400yr.old festival where wild horses are rounded up in nearby hills and herded into an arena called the Curro of Sabucedo (a kind of big stone corral), where they are sheared and branded.
Fourteen of these Rapa Das Bestas occur across Spain between June-August. The one in the village of Sabucedo (4-7th July this year) is the most well-known: since 2007, it's become an international tourist event.
The Shearing of the Beasts evolved from a tradition of caring for the animals and keeping them cool in the summer by shortening their hair. The purpose was to keep track of the different groups of horses that lived in the area.
That's all well and good...but do you see much caring going on? See the big brave villagers (and tourists!) leap onto the horses, grab them however they can (while spectators look on), and immobilise them to cut their tails and tag them. This is not the American Wild West of the 1800s! It's not Don Quixote's 16th century Spain! It's akin to the tourist stupidity of Running the Bulls! The traditional reason's long-gone: now it's bordering on brutal barbaric bravado! Further, it's unnecessary: in a civilised society, this animal maintenance (the supposed reason) can easily be done more gently and humanely.
I believe there's a time and place for preserving old traditions and customs but, when animal cruelty or outdated actions are involved, then events such as this (and bullfights, the grindadráp, La Mattanza, Toro Jubilo, Luminarias etc) should all be BANNED!