How to introduce a new, untrained dog to an aggressive dog pack?

A few thoughts here: first, esteemed PhD level animal biologist Ray Coppinger debunked the "alpha" concept when it comes to dogs several decades ago, but the idea seems to persist for some reason. Second: you should always introduce a new dog to existing members of your canine household on neutral ground. Bringing a "stranger" into your home invites territorial behavior. You don't say how long you've had the newest dog. If it is a short time, they may be working out dominance issues and, as long as no one is getting hurt, this can be okay. Sometimes, there is more noise and posturing than anything really serious going on. Not being there, I can't know for sure. If you are really concerned, or if blood has been drawn, I would ask your vet for a recommendation to a canine behaviorist (NOT the same as a dog trainer!) for help. Good luck with this!

There are some articles here that may be worth reading. http://www.veterinarypartner.com/Content.plx?P=SRC&S=1&SourceID=47 Every new dog is a new pack member with thier owne personality. A new dog is challenging your other dogs place and potentially taking resources (food, toys, attention). You need to slowly make introductions and not leave the dogs alone unsupervised until they have reached a stable peace. http://www.veterinarypartner.com/Content.plx?P=A&A=2465&S=1&SourceID=47

Pack dynamics aren't really a thing with dogs, (it's a construct of wolves kept in captivity) so it may be that they are still in the "settling in" period, especially since you didn't mention how long ago you added in the third dog. Adding in a new pet can be stressful for even the most socialized and well-behaved of dogs, and as they try to determine what the new dog is like it may lead to scuffles. If they become upset, agitated or try to get away from each other, separating them all for a while in a time out and letting them relax before reintroduction can help. Removing items of contention such as toys, bones, treats, bedding, etc can also help to reduce any fights over these items. Pheromone diffusers placed in the house can also help reduce tension between new pets. Dogs are also very good communicators, so if one of your dogs hackles or growls, it's a sign that it is time for a time out period. You shouldn't scold or reprimand your dog for this, as that can lead to behaviors where they don't give warning prior to a fight. Instead, calmly just remove the dogs to different locations and try again later. If the problems continue even after a few weeks of being together, or seem to ramp up in intensity even with changes, seeking out a trainer or behaviorist in your area that can help you in person is best.

Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not capable of correctly interpreting dog body language. For that reason, your best option is to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Best of luck.

Thanks for using Petco Pet Education Center, formerly Petcoach! This is certainly possible and recommended but this usually requires in person training by a qualified dog trainer. I recommend you consider contacting a qualified dog trainer to work with you in person. Good luck and have a good day!

I'm sorry to hear that you're having these problems! Aggression or fighting between dogs in the same household is a complex behavior issue that's very difficult to address without evaluating the dogs in person, because there are so many factors to consider - it's important to assess both dogs' personalities, how they interact with each other when they're not fighting, how severe the fights are when they happen, what seems to trigger the aggressive behavior, etc. For this reason, I would strongly recommend getting in touch with a veterinary behaviorist or a good reward-based trainer who can work with you in person to help determine why the aggression is occurring and put together a detailed treatment plan to address the problem. In the meantime, I would recommend keeping the younger dog on-leash whenever he is around the older dog to prevent any bullying or harassment, or using a baby gate or other barrier to keep the dogs separated until you are able to get some hands-on guidance in how to help them.

Thanks for using Petco Pet Education Center, formerly Petcoach! These behaviors can sometimes be changed or modified and improved. However, this usually requires in person training. I highly recommend that you consider contacting a local dog trainer who can help you in person. This can improve but does require a profesional to help you in person. Good luck and have a great day!