Some participants of the Thoroughbred industry need to be incarcerated.. I won't delve into that.
What I will say is by and large they are the best treated horses on the planet. Bathed daily, inspected by vets at least weekly but often daily, properly fed and well exercised. They spend the majority of their life either in extremely clean stables or on well maintained farms. Would I eat one? Not knowingly. Even if I were to knowingly eat horse meat I think I'd choose a more lax variety. Thoroughbred would have to be tough.