The U.S. military recruited dogs to serve during World War II. Families were asked to "enlist" their dogs for service in the newly formed canine unit. Trevor Jones tells the true story of one such recruit in "Major: A Soldier Dog." Some 17 thousand were part of the "dogs for defense" program.
http://accesswdun.com/article/2020/8/932394/listen-major-a-soldier-dog