When I started agility the only 'acceptable' reinforcer was a toy. And it was considered important that dogs tug, and retrieve this toy. It was normal to touch the dog repeatedly, pretty much piss them off until they death shook and growled when playing tug. Because good agility dogs tugged. I was also told by a agility instructor I paid for lessons that Deo would not be successful if he couldn't retrieve a toy. I still remember being in a workshop with people doing agility skill work, while she pushed Deo to try to get a retrieve.
Times have changed. Thank goodness! And every new challenge Deo gets (up to 84 now) I think of that instructor saying Deo would never be a good agility dog because he wouldn't play tug.
These days there is a much better understanding of the fact that different things are reinforcing to different dogs.
Reinforcement, by definition, increases the chance of a behavior occurring. So if your dog sits, and you give him a treat, and he sits again that treat was reinforcing. There are SO many things that are reinforcing for dogs. Play, chase, tugging, plucking a furry toy, food, chasing a bunny.... all reinforcing for many dogs!
Grid LOVE flushing the birds from my hedge (gotta love a spaniel....), it's highly reinforcing for him. Check him out, I reinforce his decision to stay working in our agility session by cuing him to flush the birds at the end of the session.
However individual dogs find different things reinforcing. My terrier finds chasing bunnies very reinforcing, however that isn't so reinforcing for Evo, my border collie. Deo does not find toys (apart from the occasional death shake of a toy on the bed during 'downtime') reinforcing or enjoyable. Evo will take a toy over most other reinforcers. Grid, my youngest dog is my first dog who I think genuinely finds praise and cuddles from me reinforcing. Flori will take food over all else.
How do you think Evo and Flori feel about each of these markers?
Not only do we understand that different dogs find different rewards reinforcing, but individual dogs have different feelings about different reinforcers. And how they feel about a reinforcer can rollover onto a behavior that is taught with that reinforcer. So if you are trying to get your dog to tug, and they have conflict about tugging, those feeling of conflict will be built into the behavior you are trying to teach with tugging. This is the case for Grid, as he has spaniel feelings about holding a toy and keeping the treasure to himself. He gets frustrated tugging, as he wants to hold the toy and run away to have it to himself. I don't want him to have frustration or feeling of moving away from me in agility, so we don't use a tug toy.
So what do we do? You can build tug drive for many dogs using food, but this is best done separately from using toys to build behavior's. Instead focus on having great markers and mechanics for reinforcement that your dog feels great about. If this is just food, consider using a food toy, or dish to get the reinforcement off you (if needed), and also ensuring that you teach delayed reinforcement for preparation for the ring.
Grid learning delayed reinforcement in preparation for the agility ring.
Here's a summary of markers and clear communication: