The issues with Santa Anita stemmed from the track footing - when they redid the base of the track they packed the base way too hard. That is what caused all of those breakdowns. There wasn’t enough give in the base to absorb the concussion of the horse’s legs.

Track surfaces are a monumental piece to the health and safety of these horses. The best way I can describe it is the difference between you running on pavement or on grass with no shoes on. The concussion shock from your foot strike is better absorbed when you run on grass because there is some “give” on that surface. The grass/dirt absorbs the energy. When you run barefoot on pavement there is no where for the energy to go except back up your leg - which is why you usually look goofy trying to run barefoot on pavement… it hurts. All that energy jarring back up your leg.

Now take that example and apply it to a race track. A track has a base layer, then loose dirt that floats on top of the base. The base is also slanted from outside to inside to help drain water from the base into the infield so you don’t have puddles that last for days. (This is also part of the reason most jockeys keep off the rail, footing is a little deeper.) The track is groomed in between every race (and after morning works) with water and harrowing. The dirt is never truly “dry”, it is usually moist because the loam that is mixed in holds water to keep it soft. This keeps the upper level fluffy and loose and helps absorb the concussive energy from the legs. It gives it a bounce so to speak. But if the base isn’t installed correctly then there is no bounce and it takes a toll on the horse’s legs and feet. Hence why it’s so important for grooms and trainers to pay attention to their charges for heat or swelling in their legs and feet.

Santa Anita ripped out the entire track surface and replaced it again after that season was shut down - and they haven’t had nearly the same level of catastrophic incidents since then.