Thoroughbred

 Geraldine Brooks' book Horse is about a real race horse.  There are four main characters: Lexington, Jarrett, Jess, and Theo.

Lexington was a horse and his trainer, Jarrett.  They grew up together and went through life, war, and blindness, together.  Jess is researching the skeleton of a horse, which turns out to be Lexington.  Theo is a PhD researcher, who comes across a painting of Lexington.  

I found it interesting that Jess found out the reason why Lexington went blind.  Even in the painting, his eyes are opaque.  The horse must have had an abscess in his tooth, and it traveled to his optic nerve.  

An important thread in the story is racism.  Jarrett is a slave and his life reflects that.  Jess is white and wonders where her relationship with Theo, who is Black, will lead.  It would spoil the story to tell you what happens to Jess and Theo, so you'll have to read it, yourself.  Sorry.

You won't regret reading Horse.