Q: Hi, we recently adopted a 3-year old male unaltered Yorkie. We plan to have him neutered ASAP, however he has an infection right now, so the surgery has to wait until that is cleared up. Ozwald was very timid and fearful the first few days, but has quickly bonded with the family, most especially me (the mom). Oz is still somewhat timid with the three male household members, but is never aggressive with them. The problem is that Oz is very aggressive to my 20-year old nephew. He barks uncontrollably whenever my nephew comes in the house, and has even nipped him on two occasions. Oz only behaves this way toward my nephew in our house. On the occasions that he saw my nephew in other settings, (the veterinarian's office, etc.) there was no aggression at all. My nephew always speaks kindly to Ozwald, and gives him treats, but Oz will take the treat then resume the aggressive behavior.

Thanks for any help you can give me! Lori

A: It may take quite some time to solve this problem--or figure out how to safely manage the dog--and in the meantime I would be concerned that he's also going to go after other people who come to your home, especially males. You didn't mention ages, but if you have children, of course there is concern about them and their friends.

Two causes of this behavior in an adult dog (and there can be other causes, but these are likely ones) would be harsh treatment at the hands of a male in the past, or simply not enough experience with males to get used to them. It's possible for a dog with either of these problems to be rehabilitated, in some cases. You have to be sure, though, that people are safe while you are working on it.

If there are children in the house, a dog who shows signs of aggression is just not a good risk. It would be wise to have a local behavior specialist come out and evaluate the dog in the presence of the family members, and diagnose the problem. Someone who is expert with the Yorkie breed might also be a good person to help you make this determination. They need to observe the dog, not diagnose online or on the phone.

Some dogs object to the person entering the territory. I had a dog like that, and two things worked. I could meet the person out front with him on leash and all of us come in together, and he was fine with them. Or I could confine him in another part of the house (where he could not see them come in), and bring him out to meet them after they were settled inside. He accepted them happily then, too. A dog who calms when the person comes in, but then erupts again later--that doesn't sound like territorial guarding.

Many times when we believe a dog is guarding our property or our persons, the dog is actually guarding himself. He's afraid and is being defensive. Systematic socialization, including all kinds of positive outings and obedience classes, can help a dog learn to view people less fearfully. Sometimes it is a very long process. The question for you to decide is whether you can protect people from being hurt by the dog while you try to work through the problem. Even though he's small, someone could get hurt, get an infection, facial scarring--dog bites are just not acceptable.

Depending on the reason for the aggression, it often gets worse after he settles into the home. At the same time, of course it also gets harder for you to give him up. I would definitely recommend some in-person help from a local expert before things go any farther. Your veterinarian may be able to recommend someone.