We have a 13 yo toy fox terrier (spayed) and a 1 yo yorkie Jax (neutered). We have the opportunity to possibly adopt a 2 yo biewer male (unneutered) he has been bred (don't know any more yet - he's supposed to be 7 or 8 pounds so I don't imagine he would be in high demand as a breeder
).
Our older dog is pretty sedate and we have wanted to have Jax a more active playmate as he is very friendly and loves when his yorkie buddy visits. So, we are seriously considering this and in fact, are going to meet him and find out more tonight. Of course, we would neuter him immediately. If you have any experience with this would you please post.
My concerns so far would be aggression from new pup, marking and would/could it stop after neuter.