I'm gonna take a wild guess that the horse she was based on had to be put to sleep because of a severe injury.

ETA
I tried my hand using Google and so the translation might not be accurate and or bestly worded

Amoriderefarfalla said:
---

In its own way, a different sort of sadness. Tachyon ran four races, completely dominated all four of them including the first leg of the Japanese Triple Crown, and then was retired because of a leg injury.

He had an incredibly successful breeding career, though, taking after his father Sunday Silence. He had, if the rumors are correct, over two thousand foals during his stud years, and could have had more had he not tragically suffered sudden heart failure at 11 years old.

MoltenSlag said:

In its own way, a different sort of sadness. Tachyon ran four races, completely dominated all four of them including the first leg of the Japanese Triple Crown, and then was retired because of a leg injury.

He had an incredibly successful breeding career, though, taking after his father Sunday Silence. He had, if the rumors are correct, over two thousand foals during his stud years, and could have had more had he not tragically suffered sudden heart failure at 11 years old.

Run free, Tachyon. 😢🐎