May 27, 2013: There has been some debate as to whether gaited breeds would be marked down for not demonstrating a two-beat jog/trot when doing a Western Dressage test. They should NOT be marked down. They should demonstrate a proper gait for their breed type instead of the jog/trot when called for in a test.
Here is the reference: FOSH Dressage Rules & Tests, Independent Judges Association Manual for Gaited Dressage (http://www.fosh.info/pdf/IJA%20Dressage%20Manual%202012.pdf.
Your show judge may not yet have this information as it just came out, so please be sure to bring a complete copy with you to your show, so you may politely bring them up to speed before your show starts. Go, gaiters!