Star ship on Saddle Mountain

I think I would have loved this story when I was about 13 years old. Not so much now that I am older than dirt.
A boy and his horse get kidnapped and taken in a spaceship to have wonderful adventures. It has its moments.
Slight spoilers: Some things made the story not work for me. The aliens are slightly different looking humans, but that is never satisfactorily explained. Also, there is a lot of hand-wavium science and just plain wrong science.