aggressive play

Question
Hi,
I have a 2 year old female spayed Great Dane that I adopted from a shelter about 2 months ago.  I am having some issues with her.  I go to an off lead dog park daily.  Lucy loves to play with other dogs, but will often grab the back of the neck of dogs when chasing them or when playing with a dog near her play ability/size/energy level.  This especially occurs in chase with more submissive dogs.  She doesn't do this with puppies.  I am having a very hard time correcting her in the moment.  Partly because I can't get to her and she doesn't seem to hear me in the excitement of play.  When I can reach her, I tell her no and take her out of play (time out).  It is often hard to catch the exact moment she is doing it and correct in the moment.  Any training suggestions?  BTW, I have a Shibu Inu/husky mix that we have had for a week or so, also.  She does not play this way with him.  She is very egalitarian-sometimes laying down submissively to play and sometimes dominating, but rarely grabbing his neck.  I have to say that she is rather stubborn.  I often have to give her commands repeatedly before she obeys.    I would greatly appreciate any advice you have.  Thanks!  Tracy

Answer
I don't know if better leadership would make enough difference or not.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

If you don't get it under control, you may need to try a private trainer.