About the author
Newlin B Wildes was an American author, who worked for Photoplay and the publishers Curtis Brown. He contributed short stories to publications like Argosy, and wrote two horse books, The Best Summer and The Horse that Had Everything.
Finding the books
Both are easy to find.
Links and sources
Newlin B Wildes at IMDB
Pony Book Chronicles – a review and much other information besides
Terri Wear: Horse Stories: An Annotated Bibliography
Thanks to Lisa Catz for summaries and photographs
Bibliography (horse books only)
The Best Summer
Rand McNally, Chicago, 1965, 79 pp, illus Albert Micale
Martin is 16, loves horses, and has a summer job lined up at a riding stable. But his father does not approve of the place. Then a relative gets him a job on a dairy farm in Vermont, that also raises horses. It proves to be a summer of hard work, adventure, fun, and an eye opener for Martin, who comes from a wealthy family. Martin becomes attached to a young Morgan/Arab filly named Sally, and works with her in his spare time. If things work out, he hopes to someday own her.

The Horse that Had Everything
Rand McNally, Chicago, 1966, 128 pp, illus Albert Micale
A review of The Horse that Had Everything
When Mr Corcoran orders a crippled Thoroughbred colt; just three months old, put down, Rick is horrified. He asks Mr Corcoran if he can have the horse, as he hopes the horse is not permanently disabled, but will grow out of his difficulties. Rick is right, and he and the horse form a strong bond.

SHORT STORY
Young Man on the Way Up
In Wildfire, the Red Stallion, ed Joe L Wheeler, Pacific Press