2 female dogs playing

Question
Both dogs are spayed. It seems the bottom of your answer was cut off.  Was there more to your answer?
Thank You
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
Hello,
I have a Yorkie puppy Daisy 11 months old.  My neighbor has a schnauzer about 20 months old and she has been bringing her over for play dates.  The last few time the Schnauzer has become very aggressive and gets on top of the little yorkie and growls and snaps until the pup is yelping.  I would think she should back off is the pup is yelping but she keeps hurting her.  My neighbor keeps making excuses for her dog but I have a bad feeling about this.  This Schnauzer is much bigger than my pup.  
Any advise or should I just stop the play dates?  They use to have fun before.
-----Answer-----
Sometimes it is hard to tell what is going on, but the Yorkie yelping sounds bad.  Retreating when it get a chance and not coming back, is a certain sign the other dog is being too rough.  The Schnauzer is maturing and may be exerting more dominance than the Yorkie will accept.  Neither may be getting the training it needs.  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/  Such problems are even more likely if neither dog has been spayed.  For the average dog owner, there is no good reason for not spay/neutering.  Many people do not understand how difficult it is to breed quality dogs, and we have no need for more people to be getting into breeding.  A spayed female is a better behaved dog, will have a longer healthier life, and never give the owner the hassle of being in season twice a year with all its dangers.  And, yes, I am concerned about all the dogs slaughtered in the shelters.

Unless your neighbor changes how she manages her Schnauzer, it would be better to find another playmate for your Yorkie.  I have seen

Answer
Oops! That happens sometimes.  I write my answers and everything else in NS 4.8 because I never found anything else with as friendly and powerful spell check.  I am spelling and typing impaired and desperately need a good spell check.  

I guess I was going on to say different sized dogs can enjoy playing together.  I am attending a meeting tomorrow.  Most of the dogs will be larger breed puppies, part of a dog guide school program.  Since it is at the leader's home, we are free to bring other dogs too.  I will be taking my 3 1/2 month puppy, plus my 13 year old retired dog guide.  The hostess has Cairn Terriers and sometimes somebody brings a Beagle.  The dogs spend most of their time in a large fenced back yard.  We seldom have to settle anybody.