Zucchini Out West by Barbara Dana

Zucchini is Billy's pet and his best friend. When biologists at the ASPCA think that Zucchini is a rare black-footed ferret, Billy is in a quandary. He loves animals and does everything he can to help the ecology, but realizes that he can't keep an endangered animal as a pet. Can Billy do the right thing and risk losing Zucchini forever?