Lab Wont Accept New Dog

Question
We have had a three year old male lab, Chester for three years now. Recently we wanted to get another dog as a playmate for him. We got a female Great Dane at the Shelter, eight months old and a real love bug. When they were first introduced, they met outside on leashes and just sniffed each other. Everything seemed fine. The next day, Chester saw Cheyenne (GD) in her crate and started growling and barking continuously. We took him out of the room. The following day, Cheyenne went downstairs to where Chester was. Chester growled, snipped at her and continued to bark. Chester does not seem to want to accept her at all. She shows no aggression toward Chester at all and I think only wants to be his friend. I have gotten several suggestions; taking them for walks together on leashes, putting leashes on them in the house. Keeping Cheyenne on a leash and letting Chester run free. I'm not sure at this point what to do. I don't want either one to get hurt. It makes me sad that they can't get along, due mostly to Chester. Cheyenne is spayed and Chester is due to go in to be neutered in a few weeks. Please advise. I'm open to any suggestions you may have to solve this problem.  

Answer
Having a good pack structure reduces such problems.  The 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/  You may have already obedience trained him, but Chester never learned you are top dog.  

Spending some time drilling him now will not only help teach that lesson, it will also show him he is still an important member of the pack.  Do all the top dog stuff, go through doorways first, he sits before being let out, before eating, etc..

Usually a spayed female and neutered male is the best combination.  He is still young enough to enjoy having another dog to play with and to adjust to not being the only dog.  Has he had regular chances to play with other dogs?  If so, that should help.  Most puppies enjoy rough play losing interest as they age.  Visitors are usually much more welcome than new residents.  We have a number of dogs coming and going, usually for a short visit.  Visitors are always welcomed except our 11 year old Lab finds puppies a little much.  She especially dislikes our 7 month old Sheba. We had a 10 year old visit, and he didn't like Sheba either.  The few times we have brought a new dog into the household, the old dog seemed to sense it was long term and was slow to accept it.  In each case, it was 2 females, at least one of which was intact.  

It sounds like you have done your best.  I don't know if meeting on neutral ground helps much or not.  Certainly it can't hurt.  I would not leave them alone together for now.  Give him time.  Continue to give him plenty of attention.  Keep a close eye on what is happening when they are together.  Sometimes it is hard to tell play from aggression.  Here is a link showing my Shepherd playing with a visiting Lab, http://www.photolocker.net/images/Labman/labmanellagretchen.jpg  On the other hand, I didn't realize what was happening another time with my Lab and a friend's Lab until I saw the fur missing.