Ok. I want to give you my thoughts on your situation given the facts you have already given me so you won't have to wait on an answer.
Dogs are pack animals and there is a boss and followers. What you have is two dogs who have been the only dogs in their respective households for at least some period of time. One dog (1) does not seem to have been socialized much while the other (2) seems to have been socialized around other animals and possibly people as well and house trained too.
When you bring too dogs who have been used to being the boss dog in their household together, you are going to have some adjustments since both dogs are used to being the boss. Since 1 was there first, her smell was over the whole house and since she was there first, 1 believes that she is indeed the boss of the house. The fact that she was not socialized before means she may not know how to be the alpha dog or feels the need to constantly remind dog 2 that she is the boss.
One way a dog will show they are the boss is to mark around what they believe is their territory. Thus she would urinate in various places around the house to claim the area. She might also urinate on the other dog's bedding to show that dog that she owns everything which isome alpha dogs might do to show another dog they are boss. The attacks are likely #1 dog's attempts to make #2 submit to her. Alpha dogs feel they own everything and it is their right to get respect from other dogs in the household. They feel they should eat first, get affection first, get treats first and even go outside first. Since the dogs are owned by different people, each person is going to be treating their dog special such as giving affection to their dog and treats to thei dog and each dog has their own toys.
The alpha dog (1) won't see it that way. To her, only she should get attention first and treats first. Since she really can't attack the owner, she redirects that aggression toward the other dog so the dog realizes that they shouldn't be accepting the affection or treat until the alpha dog lets them.
Many experts recommend letting the dogs sort the situation out which they will with time, and if there is no serious bloodshed is not such a bad idea since eventually they should settle down when the less dominant dog submits totally. However, with the first dog not having been socialized, she might not realize that she doesn't have to reprimand #2 dog all the time so it might take longer.
Let's discuss possible solutions to the problem now. The first thing is to clean thoroughly to get rid of the urine odor. Use an enzymatic pet odor cleanser to thoroughly clean the areas either dog has urinated. Allow it to soak in thoroughly to reach anywhere the urine did to break up the protein and remove the odor. It may not smell to you, but dog's have better noses and if an enzymatic cleaner was not used, there is still an odor there and that will draw a dog back to the spot to urinate again.
The next step is obedience training for #1. She has to know that the humans are the boss and not her. So far it seems she has been pretty much allowed to do what she wanted. Obedience training will help teach her commands but also that the humans are the boss and she needs to obey them. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
If she sees the people as the boss she won't be as inclined to protect the house from visitors either s it will be the human's job to do that. You can also train her to sit and stay when visitors come to the door. When first teaching her to sit at the door when visitors come, you can slip the leash under your foot, have her sit and use the leash to keep her in that spot in a sit or down position as you open the door. Initially she will fight it, but soon will realize it doesn't do any good to try and move away and will stay. When she does that reward her with a tasty hot dog sliver treat. Have visitors reward her as well. This helps her see that visitors are not bad people as well. It will help socialize her.
You may also want to have her go to a group training class for the socialization with the other owners and dogs. I'd get some training done at home first so it is more a socialization session and obedience with distraction training.
Now the barking is also something that requires training. As crazy as this sounds you may wish to teach the dog the speak command and then the quiet command. It seems easier to teach the quiet command after the dog has learned the speak command. The following site explains teaching speak and quiet commands.
You also have the option of getting a bark collar such as citronella spray collar or shock bark collars that will stop excessive barking. It is definitely the fast quick way of solving a barking issue and is effective. I personally believe in training unless the problem is happening when no one is around the dog to give direction.
Now the dog might also have a medical issue such as hypothryoidism, so a thyroid panel needs to be run to be sure. Hypothyroidism can cause excessive aggression. Once that is ruled out and I think it is more likely behavioral, then you will know that the training is necessary.
You will want to train both dogs but focus on the aggressor which is the number 1 dog. Additional training can also help. Both dogs should be leashed and if one dog even looks at the other dog, a correction should be done. Any sign of aggression including a prolonged look, hair raised on the shoulders, a growl or even a stiff legged walk, should be corrected. A correction is a quick tug of the leash and a firm low toned "NO". Once you have done this a couple of times, you should notice the dogs ignoring each other. When that happens, you will want to reward them for the desired behavior. Again, use tasty treats like the hot dog slices. This teaches the dogs that you WILL not tolerate fighting in YOUR pack.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.
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