Running of the Bulls events are gratuitous spectacles of animal cruelty for the sake of nothing more than entertainment and a fleeting sense of bravado. Organizers put the health and safety of both humans and animals at risk and the events should be stopped before there is serious injury or death.
Bovines in general do not have much physical stamina due to their heavy weight. They will suffer from stress (fear during transport, being restrained, forced running...) and exhaustion (heat, running...). Their vocalizations will call other bulls or cows letting them know that something bad is happening there. They may be intentionally teased, provoked and agitated prior to the run.
Over 13 people have died from injuries in the Pamplona bull run over the past 102 years. The last death was in 1995, when a 22-year-old American was gored. The injury count is over 113.
Don't let this dangerous precedent be set for America!