Why has my dog gone from very beta and passive to an aggressor that starts fights?

with the alpha(you) being gone a new alpha was needed so that is part of the cause of the fighting and huskies reach full sexual maturity by 2 so although they are fixed it is probably a mix of being leaderless and hormones. Make sure food isn't the problem and if it continues find an animal behaviorist or dog trainer

It sounds to me as if your boyfriend probably was not honoring the dominance heirarcy between the dogs and has created confusion in them. This on top of adding a new dog has caused things to spin out of control. If you can identify the dominant dog in your pack you need to start treating him as such. While it seems unfair to humans to "play favorites" this is what is necessary to restore peace and calm into your home. Your alpha dog needs to be the first for everything! Examples: when you get home he gets the irst greeting and pets (and then pet the other 2 in order of their ranking as well. At meal times alpha gets his food first. He gets his treats first, his leash put on first (and out the door for walks first). By treatting the dogs in the order of their pack heirarchy you can aid the alpha in regaining control over the other 2 dogs and demonstrate to the entire pack that you understand their places within the home. If your bf happens to be more fond od the beta dog he may have been inadvertently showing him more favoritism causing the beta to feel superior to the alpha which is why he is now trying to undermine the other dog. The tips above, paired with ample exercize for those energetic huskies should help restore balance to your home.

I write a dog blog @ www.shespeaksbark.blogspot.com - if you go there and search "nothing in life is free" in the search bar @ the top left it should pll up an old article I've written- I think those tips would also be an aid for you and your lovely dogs. Good luck- huskies are simply the best!

Dogs need socialization. Dogs do not warm up to other dogs on their own automatically. They need to know that its ok to have other dogs around as well as other people. In fact, its the one most important thing in training a dog so that it doesn't lead to aggressive behavior. Take him around other dogs constantly and treat when he's calm and plays well. As far as your new dog goes, be in the room when they're together. Treat them everytime they play well and even really look at each other for a couple of days. This will cause positive associations with your new dog and will let him know he doesn't have to fight for anything....especially dominance, since that's your position not any of theirs.

It sounds to me like you *was* the leader.

Then you left and your boyfriend wasn't a good leader so they had to decide between themselves who should take charge.

When you came back, you have acted in a weak way towards them fighting and therefore have not reclaimed your leader status and therefore they continue to fight.

Personally, i'd tie them up just out of reach of each other for a while and see if things settle down over time.

If not, i'd consider either getting rid of the new arrival or calling a professional in.

One thing as that neither of these dogs are neutered and are fighting for dominance.

Mounting is a sign of dominance...and the younger dog is trying to dominate the eldest dog...please neuter them and find an animal behavorist.