What is this book? Help!

When I was growing up, I read everything that I could get my hands on about horses. Black Beauty, Walter Farley's Black Stallion books, countless novels by Marguerite Henry, plus nonfiction titles like The Encyclopedia of the Horse.

For some reason though, I've been thinking a lot lately of a specific book - but of course, I can't remember the title or the author (although I'm pretty sure it was a female author). EDIT: Oops, nope!

The plot, as I recall it: There's an adolescent girl who is in love with horses. She wants one of her own, but her parents are against the idea. She gets stricken with polio, and has difficulty recovering. Her parents think that buying her a horse will help inspire her to work harder to walk again. So they buy her a horse. Towards the end of the book, there's a robbery or something (I can't remember exactly) and it's up to the girl to drag herself onto the horse to save the day. Or something. I can't remember exactly.

The only other detail I remember is that yew bushes are mentioned. That probably isn't helpful, but I often remember little inconsequential things about books I read. For example, I read To Kill a Mockingbird twice in high school and the only thing that's stuck with me is when the town drunk reveals to Scout that the booze hidden by his paper bag isn't actually alcohol. Go figure.

Photo Credit

Update: Thanks to Candice who figured out that I was looking for Tall and Proud by Vian Smith!  I thought the title was familiar, and then when I looked up the cover I knew it was the right book: 

Tall and Proud