Originally published as Lion in the hills. Dodd, Mead, 1961.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Mountain-lion : a puma called Rusty by John Brewster Prescott. Published by Deutsch in 1962. Publication and catalogue information, links to buy online and reader comments.
obnb.uk is a Good Stuff website.