Yet another bit of 'advice'. You know how when you read up on certain breeds, they mention: 'may be aggressive, not for beginners, etc'?
This 'Red Zone' Rottie is an example of that. If you bring such a pup home, do not establish boundaries, weak obedience training, improper socialization, etc.,and allow him to reach maturity under these conditions-big problem. This dog is responding to his prey instinct when he encounters a barking small dog. He is not responding to his owner, because the owner has not addressed this when he had a chance, (socialization).
This dog does not belong in a campground,(small dog central). The owner needs as much training as the dog. The owner failed this dog. If the owner does not assume the Alpha position, the dog instinctively fills the position. A large dominant male Rottweiler has no trouble stepping up to the Alpha position, unless a dominant owner takes over. Lots of beautiful Rotties in the shelter for the same reason.