As with humans, greyhounds run at varying speeds, so in order to give all dogs in any race a chance to win, the sport uses what is known as a "grading system". The best dogs at a track are usually in grade 1, the next group are grade 2, etc. The total number of grades varies from track to track. The grade is accompanied by. Greyhounds that win their way out of maiden class and would normally become a Grade 5 but will now become a Grade 7. Once a greyhound wins a race as a Grade 7, it will become a Grade 6. Grade 6 greyhounds will have won no more than one race outside of Maiden Grade (excluding Qualifying Heats). I don't know much about greyhounds, but I'm trying to learn, and I can't find anywhere explaining what the race grades mean exactly? I've got the basics I think: OR = Open Race (any dogs can enter??, but basically attracts the best dogs??), A-numbe. You are about to the double watch a violation of the comment Terms and Conditions. Additionally, the National Greyhound Association holds their membership to strict standards towards the care and handling of the dogs. If you want to bet on a forecast or tricast then you have to do this on the Tote. Mullingar will have a Sprint Rating of Fifteen states without live racing allow simulcast betting on greyhound races in other states.