How to stop my dog from being aggressive towards her 8-month-old pups?

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.

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.

If your dog does not get along with other dogs it was probably a very bad idea (and a very stressful one) to bring a new puppy into the house. A new puppy can also be hard around a newborn as they aren't yet sure how to interact with each other. You can try to continue to get the two to get along by starting with limited introductions that are supervised, however if a fight breaks out the interaction should be stopped immediately and started again later. Never leave the two unsupervised together as even a good play sessions can cause accidental injury. You can also use baby gates as a way for the two to "meet" each other without being able to physically be together. If fights are continually breaking out, talking to a trainer or behaviorist that can observe within the home is best.

I hate to hear this is happening. I;m sure it's not only scary but stressful as well. Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend 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. Also, dogs who are spayed and neutered are less likely to fight though this is not always the case. I recommend to discuss having both dogs altered with their veterinarian. Best of luck.

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.

Hormonal changes that occur after being spayed or neutered can sometimes cause tensions. Keeping the dogs separated unless supervised may help reduce fights. If you notice one or both dogs becoming too excited or agitated, separating them and giving them a chance to cool off can help. Removing items of contention such as treats or toys can also help reduce fighting. If the fighting continues, or they are unable to be together at all, seeking out a local veterinary behaviorist or trainer in person that can observe their behavior may be useful for formulating a training plan to help both dogs get along again.

A certain amount of rough play is normal in puppies. If they get too rough, simply separate them until they calm down. Praise and reward them when they behave. Correct any negative behavior immediately. A pheromone product, such as the Adaptil collar or DAP plug in diffuser, may also help to calm them down some.