In 1920 Canada boasted about 3,500,000 horses, per- forming heavy, useful work on farms, cattle ranches and in cities. But in the years since, with the development of heavy trucks and efficient farm machinery, auto-makers have more and more forced horses from the road and put them under the hood of today's sleek automobiles. Today, Canada's horse population has shrunk to about 900,000 animals, and it's dwindling every day. With the exception of a few dray horses still doing daily battle with big-city traffic, Canada's supply of equus caballus is now pretty much relegated to doing minor farm and ranch chores not yet touched by mechanization.