IIRC, the only reason Junior continued to leave a carbon footprint was that Patrick's family requested he not be put down. (Mind you, this was 25 years ago, so the details are a bit hazy.)
The thing is, that as sad as this is, this young girl could have died of illness, been in a car crash, drowned etc. Because it was a rarer accident, horses and jumping are getting more attention. Horses are good for kids most of the time IMO. That doesn't mean an adult shouldn't be around to supervise safety though.
If that horse ever hurt somebody else again, they'd have it on their consciences, but the owner would be set up for a big punitive damages verdict.
That's the "One Bite Rule".