The Toro de la Vega festival is unique in that after the bull is run through the town, chasing daredevil participants through the streets in a similar fashion to Pamplona's famous San Fermin event, the beast is not fought by professional matadors in a ring.
Instead, all comers battle for the honour of killing the animal out in the open plain, some on horseback, others on foot. The winner of the tournament trophy is the one who lands the mortal wound on the bull, bringing it to its knees before an accredited expert deals a coup de grace to the animal's neck.
Supporters of the nearly 500-year-old tradition say it is the purest of battles between man and bull, pointing to strict rules against wounding the animal from the side or attacking in numbers rather than one by one.
Don't kill animals just for fun! We're not troglodytes Help us! "Rompesuelas needs your help! NO Toro de la Vega pic.twitter.com/5g5yfUsOPg
— Jesusf. (@Jesusf_Malaka) September 15, 2015
If you don't know "The Toro de la Vega" it's were a bunch of cretins with spears stab a toro over and over again until it finally dies.
— Ooh no you didn't.. (@VKateMitchell) September 15, 2015
Despite thousands protesting against abuse, the next victim of the Toro de la Vega is set to be killed tomorrow. pic.twitter.com/Spt2fectXX
— jc.....55! (@jczv) September 14, 2015