Looking for a fiction YA (perhaps adult) book from the early to mid 60’s that I read in junior high. I was given the book as a present. It’s about a lamb that gets lost in a forest/jungle. I remember that it had a jaguar, panther or puma that befriended the lamb and helped keep it safe. There were no illustrations that I recall; strictly text. It was a fairly long novel, about the length of the Harry Potter novels. The book had a green hardcover with the lamb and trees on it. I want to say that the lamb on the cover was black, but can’t be sure. Does anyone remember this book? I know it sounds vaguely like The Jungle Book, but that really isn’t it.