This article is from the Complete List of Dog-Related Acronyms, posted to rec.pets.dogs newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
Advanced Trial Dog
Open Trial Dog
Ranch Dog (dog has been evaluated by a judge while doing its routine farm tasks & certified to be a useful working dog)
Started Trial Dog
Working Trial Champion (prefix) (dog has earned ATD on all 3 types of stock)
* Always with suffix -s, -d, -c to indicate title earned on sheep, ducks or cattle. Titles earned separately on each type of stock.