shih tzu aggression

Question
We have a 9 yr old rat terrier S/F,  6 yr old Golden S/F, 2 yr old shih tzu N/M, and have just gotten a 12 wk old female shih tzu. Within the first week of getting the new puppy, our 2 yr old shih tzu has been very nasty towards the puppy. She tries to play with him and follows him around. All he does is run away which causes the puppy to think he wants to play. Then he'll bark aggressively and go after the puppy. He has snapped at her and bit her. She's only 4lbs and I'm afraid he'll hurt her. Being the only male dog, even though he's younger than our Golden and Rat terrier, could it just be him trying to prove himself as pack leader? Will it just take adjustment time? What is the best way to approach his behavior?  Thank you SO much for your help.

Answer

Hi Ellen,

Congratulations on getting a new puppy!
Sorry for the delay in getting back to you. Allexperts isn't sending me alerts to tell me I have messages waiting for me.

At just 12 weeks old, I sort of doubt the conflict is because the puppy and Shih Tzu are both males or because of "pack" dominance issues. Until the puppy goes into puberty,  your Shih Tzu won't be aware of the puppy's gender.

First and foremost, protect the puppy from the Shih Tzu. Tell your Shih Tzu "bad dog" in a stern voice to let him know your disapproval of his behavior, and physically separate him from the puppy when it's needed. Do this every time he's aggressive towards the puppy. By the same measure, protect your Shih Tzu from the puppy, who doesn't know when your older dog has had enough.

The Shih Tzu's aggression towards the puppy might lessen in the coming weeks, it's only been a week or so since you got the puppy. It can take a month before a dog adjusts to changes in it's home. When your Shih Tzu is calm and not being aggressive, let him see good things happen when the puppy is around. Give him treats, and tons of praise every time he's calm in the puppy's presence. When you finally find a fun game they will enjoy doing together, and will finally playfully interact more with each other, gracefully bow out. Let them focus on and enjoy playing with each other, not you.

This might be helpful reading for you:

http://www.adoptapet.com/blog/introducing-a-new-puppy-to-your-adult-dog/

Best of luck,

Patti