Both our Bunny and Eli do this. I used to play with B this way.. not really realizing that this was influencing her aggressive behavior. And then when we got E, he wanted to play that way as well (he's 8 mo old now too).

Since we don't want to encourage that behavior... When either of them does it, I pull my hands up to my chest and give a firm No. A few 'No's will usually stop them.. but if thats not enough, I'll push them down to the floor and onto their back... in a submissive position. Thats usually a good way for them to realize that Im in control and I dont like what they are doing.

About the neutering... We just had Eli done last month.. He hasnt really changed his behavior too much. It has changed the competition between him and Zeke, which is what we were hoping for. Ive always heard that 6 months was a good ago to have that done... Because if they get too old and are still intact, it will be virtually impossible to get them to stop marking and chasing females... We have a friend with a 2 yr old dog that wasnt fixed until recently and thats ALL he does. Has to mark every BLADE of grass at the dog park...