#1 Rule: The person operating the machine is responsible for the safety of the course and the participants. Safety Tips:
ALWAYS have a pair of scissors on hand, if a dog gets tangled in the line, cut the line immediately next to where you are standing (do not go to the dog just cut the line wherever you are) and this will release the tension and free the dog.
Watch dogs for signs of overheating - slowing down, tongue hanging out, tongue curling up. Never run a dog for too long.
If you think a dog shouldn't run (they're limping or older etc.) it is the operator's choice to say they won't run a dog for safety reasons - in this case you can offer a refund. For example, I once had a dog enter the field with a bandage on their belly, the dog had been spayed the day prior - I told the owner this kind of activity could affect the sutures/spay site and refused to run the dog and offered them a refund)
The line can cause severe line burn. NEVER let children on the course without parent or guardian present and let them know the child cannot go near or touch the line.
The line will break at the drive wheel as a safety mechanism but this is only if the dog is holding the flag or standing on the line etc.
Always have water nearby the course and remind owners to give their dog a chance to cool down and get a drink after running.