Handlers with small and large dogs should be conscious that small dogs are more likely to be hurt by large dogs even if they are both friendly and are just playing. Owners of small dogs can be unaware that their small dog's behaviour may be provoking even to well mannered dogs. Both handlers should be aware of how well socialized their dog is and whether they should work on good manners.
Even though on leash, please ask before allowing your dog to 'visit' another dog. Both for safety's sake, and because it is important for the dogs to learn to wait for permission, so they can maintain focus in the ring.
Do not throw food into tunnels, this can remain insitu and be a serious distraction to other dogs.