How to introduce a new puppy when my dog is aggressive and barking?

Introduce them to one another gradually. First, by allowing them to hear and smell one another through a closed door, then by sight without physical contact, then supervised contact. You will need to progress gradually through each phase. Correct any aggressive behavior immediately and praise good behavior consistently. A pheromone product, such as the Adaptil collar or DAP plug in diffuser, may decrease any anxiety or aggression.

I recommend giving Zoe lots of attention and keep to her same routine. Often when people get new dogs they are so time demanding that the other dog gets put aside. Puppies are annoying also so give Zoe some time alone so she can relax and sleep without him bothering her. I find playing with them outside, or walking together usually helps. Feed them separately so Zoe isn’t worried about her food. In addition I would try her on an anti anxiety supplement like Solliquin. This will help her relax. Over time she should accept Rocky and enjoy having him around. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Zoe and Rocky.

Poor Merlin! It sounds like he gets very upset around other dogs, which can be a challenging problem to work on in some cases. You will need to take things very slowly when introducing him to the new puppy - this will be hard for both of them, so be patient and stay positive. For now, I would recommend keeping them separated unless you are actively working on training with them - this will help to prevent any setbacks that may occur if they get into a fight. I would try to do several short training sessions each day if you can, no more than 5-10 minutes each. You will need another person to help you, and both dogs should be on-leash. Start with them on opposite sides of the room, and give treats for calm behavior while they are in the same room together. Over the next few days, if things are going well, you can gradually start to allow them to be closer together, still giving treats for calm behavior - if either dog becomes upset and starts to bark or growl, just move them further apart again. It may take several days or even weeks before they can safely be loose together, depending on how severe Merlin's problem is. If you are not seeing any improvement within the first week of starting this plan, I would strongly recommend getting in touch with a good reward-based trainer who can work with you in person. You can search for a qualified trainer in your area here: www.ccpdt.org

It may take some time for her to accept him. If she is being aggressive toward him than you should not allow them to be together unsupervised, espeically around feeding time or any toys/bones that she may protect. Give her extra attention, praise, and treats while the puppy is around so she knows he is not there to replace her. You could also try an Adaptil collar or diffuser and see if that helps. If she doesn't start accepting him than you could talk to your vet about trying an anti-anxiety medication, like Prozac or Trazodone and see if that helps.

It can be very stressful for the existing dog when a puppy is introduced. I am not sure what you have tried already but if it is not working then you could try an Adaptil collar, Solliquin chew, or talk to your vet about trying an anti-anxiety medication, like Trazodone to see if that helps relieve any anxiety your adult dog may have. Otherwise, you may need to get a professional trainer to come and work with your dogs. Here is a link with information on how to introduce a new puppy... https://indoorpet.osu.edu/dogs/new_additions_dogs/dog-dog-intro

Separate them for a few days then gradually reintroduce them. First with a door between them so they can hear and smell one another then separated so they can see but not reach one another and finally a supervised physical introduction. Use leash, collars and muzzles if necessary. Pheromone products such as the Adaptil collar or DAP plug in diffuser may decrease any anxiety or aggression. Provide adequate numbers of bowls, beds and toys to prevent food aggression or resource protection.

You will likely need to separate the new dog from the 2 "older" dogs for a period of time. Spend time with each separately, but make sure that they cannot see the new dog, i.e. keep him in a separate part of the house behind a closed door for at least one to two weeks. Then you can allow them to see each other, but not have contact. Move slowly, from this phase on to allowing them to see and smell each other across a barrier such as a baby gate. Finally, allow them to spend supervised time together. Reward good behavior with high value food treats (i.e. bits of cooked chicken) and go slow.