Rott-n-GSDs
Posted : 3/28/2010 8:18:00 PM
A few different things may be coming into play. Do other dogs use this park? If so, there may be smells that are getting the dogs worked up. The excitement level is also likely elevated, as both are probably thinking, "Wheee!! We get to run free in a big area!" Excited dogs can sometimes become aggressive dogs (think of how sometimes dogs can get aggressive behind a fence... they may turn on their doggie friends because they are excited/frustrated about a dog or human on the other side of the fence).
Additionally, it may not be all the bullmastiff's fault. Sometimes a dog isn't intending to be aggressive, but the other dog overreacts and then a fight occurs. A friend of mine has a BC that is fear aggressive. If a dog comes up to him too quickly or displays any sort of dominant body language, he freaks out and lashes out at the other dog. A dog like a Rotti usually isn't going to back down if another dog challenges him. I would recommend tiring the dogs out with a nice long (leashed) walk before turning them loose in a field.