SOLVED. Looking for a standalone horse novel. [s]

[Sarah]

I am looking to locate a book I read between the years 2005-2008.
I read it in paperback, it had a white/grey horse on the cover with a red stall (not the book, Joey).
I remember it being around 300-400 pages, there was a young girl and her brother. It was young adult/maybe even tween novel. They experienced something life-altering, and I seem to recall the horse got loose or they somehow got back to the horse in the stall.

[Stephanie]

No Small Thing?

[Sarah]

Stephanie wrote: "No Small Thing?

"

THANK YOU SO MUCH!!!!!!!! You are amazing!~