How to introduce a new dog?

[Fred]

We have a Bichon/Schnauzer mix who I've had for about 4 years now, and we recently got my mom's Chihuahua/Schnauzer mix. My dog has always been the sweet, loving little guy and we brought home the other dog, since then he has get's all excited and starts sniffing him, about 3 times, he's snapped at the new puppy, who is now terrified of him. We introduced them by having the new guy on the leash, and letting my dog go up to him. I'm just not sure if they'll eventually work things out or what I can do to assist the process. Thank you in advance!!

 

[Love My Hubby]

I introduced my two dogs to each other off leash. Putting my eldest one on the leash would have been a bad idea. You need to let the dogs sniff each other out. The dog will probably snap and growl but they will get used to one another. The puppy will get over the fact that your other dog snapped at him. In time, they will bond.
Have them play together with a tug or a ball and they will probably pretty quickly forget they don't know each other.

 

[itsmariaokay]

Same things happend to me. i have a poddle that i've had for 5 years and i just got a chi too .. at first the poodle would snap at the chi and the chi would be so scare but what we would do is put them together but not alone as the other dog may hurt him and they will get to know each other .! days will go buy and the other dog will get used to him trust me now after two weeks they play all the time and i even leave them together when i leave but PLEASE DONT LEAVE THEM ALONE WHEN YOU LEAVE UNTIL YOUR SURE THEY ARE HAPPY WITH EACH OTHER

 

[no qf]

it's hard to know exactly what's going on but if you're sure the puppy is terrified, separate the two dogs with a baby gate, which allows them to see each other, even sniff each other and be able to exchange canine communication signals but will be safe.
it isn't fair to either your resident dog or the new dog to just throw them together and hope for the best -- it's not likely to work out.
watch the dogs closely while still separated.
when either dog gives friendly signals (doesn't have to be directly to the other dog) praise him softly and encourage him to move away from the other dog (yes, that's right - move away. most dogs who are reactive or afraid are seeking to increase distance from the object of their reactivity/fear. you can teach them that offering appropriate, calm behavior gets them what they want. eventually they start to change their mind about the scary thing and want to start getting closer all the while still feeling calm and happy).
if you're not familiar with calming signals, i recommend reading about them.
dogs have very subtle ways of communicating and if those signals are ignored, things escalate and are bound to end in a scuffle or worse.
normal dogs try to avoid conflict at all costs, but under pressure they can be pushed to react inappropriately.
it's also not normal for adult dogs to strike out at puppies under 4 months. how old is this puppy?

these websites may help with understanding calming signals and helping dogs learn alternative ways of interacting (which are based on understanding dog language):

http://ahimsadogtraining.com/blog/bat/
http://www.canis.no/rugaas/index.php
http://www.youtube.com/watch?v=MgnLgHFRJu4
http://www.youtube.com/watch?v=Lj7BWxC6iVs

best wishes to you and both dogs.

edit: oops. sorry. parallel walking is also an excellent way to get two dogs used to being with each other without the pressure of actually interacting:

http://www.k9magazinefree.com/k9_perspective/iss36p9.shtml