When I first moved out to Jacksonville (dog racing country) from Jersey, a buddy of mine explained how they once used trained monkeys as jockeys for the dogs... I almost fell for that one
Seriously, the key to handicapping dog racing is just like the ponies, watch all the races! dogs by habit and by breeding fairly consistently run in a similar path each time out. You can use that knowledge to figure out which dog may(or may not) get a clean run.