territorial mini schnauzer

Question
I have an almost 4 year old neutered male mini schnauzer.  At an early age he was socialized with other dogs.  Recently each of my daughter's have gotten puppies, a puggle and a jug, both female.  When the the jug comes to visit my dog is thrilled and the two play great together.  When the puggle is there he is consantly growling at her and has made her yelp on more than one occasion.  It's to the point if he's close by she immediately goes into a submissive state. When the two puppies are over together, he never goes after the jug.  When he sees the jug and puggle playing he's in their face growling, basically a the puggle. Yesterday a neighbor came over with a female border colli mix and he went nuts.  He started to attack her.  He is normally not an aggressive/mean dog.  Is he being territorial?  When we go on walks, I have no problem with dogs coming near him.  Is there something I should be doing when another dog enters the house?

Answer
Hi Denise

I am not going to be able to help you much here I'm afraid as there are so many components to this problem.  

what I would say is that your dog is clearly finding it difficult suddenly having two new dogs coming (regularly?) to his home.  I would be concerned about this, especially as he has since attacked your neighbour's dog.  You need to prevent the behaviour from continuing from now on as each time he bullies the puppy he is practicing successfully being aggressive, which he may then go on to do to more and more dogs in the future.

relevant information includes: age of the puppies; which was acquired first; your dog's relationship with the individual daughters; personalities of the puppies.  aggression between dogs really needs to be seen and I am unwilling to give advice without seeing it I'm afraid, as it may do more harm than good.

get a qualified behaviorist who specilaises in dog dog interactions to visit you all.  in the meantime, do not allow your dog to practice this behaviour as it is stressful for him and for the puppy, which may then have problems with other dogs as it grows up.  shut him away or in the garden or get someone to walk him perhaps, if the puppy visits.  ideally ask your daughter to find someone to look after her puppy when she visits until it has been resolved.

good luck and sorry i can't resolve it for you.

regards,

Lucy