How to stop my friendly dog from being aggressive to my other dog?

I would make sure the dog that has become aggressive isn't having any other issues like pain or discomfort. Also, has anything change in your schedule or house that could have made her feel more insecure or anxious? You could talk to your vet about starting her on an anti-anxiety medicine like fluoxetine as this may help. I would also make sure they aren't becoming aggressive over any treats, bones, toys, etc. I hope this helps and she starts to act like herself soon.

Bella is adorable. I would recommend taking Bella to the veterinarian to make sure there is nothing medical going on with her. If that comes back as just behavioral I would recommend getting a trainer to work with you and her. They will be able to see what is the trigger and work with her and you to stop the behavior. If the trainer evaluates her and determines medication is needed then your veterinarian can provide medication to help. Thank you for using Petco Pet Education Center, formerly Petcoach.

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.

Consider obedience training ( https://www.petco.com/shop/en/petcostore/s/petco-dog-training ) to redirect some of that energy. A pheromone product, such as the Adaptil collar or DAP plug in diffuser, may also help to decrease any anxiety. Provide extra toys, bowls and beds to prevent resource protection.

It is so hard when they don't get along all the time especially when they are having fights at least 1-2 times per week. I would stop giving them treats together. You can either stop giving treats or put her in a different room when treats are given. I would also consider putting her on a calming chew like vetriscience composure and a calming collar like adaptil. These are natural ways to help take the edge off. Unfortunately, they don't work on all dogs. If this doesn't help, I would talk to your vet about trying an anti-anxiety medicine like fluoxetine or trazadone. I have had some success with anti-anxiety meds in dogs that are the aggressor of a group. I hope this helps!

I recommend to focus on increased exercise for the bigger pup. The more physically tired she is, the less likely she will be to bully the smaller one. I recommend at this time to have a baby gate or some other type of barrier to separate them so that the smaller one feels more secure. Work on calming the environment with pheromone sprays and classical music. Make sure to give the smaller pup exercise as well as this will act as a stress reliever. You can also try distracting both pets with peanut butter (make sure there's no xylitol) Kongs that have been in the freezer for a few hours. Lastly, if these are not breeding dogs, getting them spayed will eliminate the sex hormones and this may help calm things down a lot (although this is not the case for every dog). I hope this is helpful and please feel free to post again if you have any further questions.

Please have Lady seen by a vet to help rule out a possible medical cause for her behaviour. If nothing is found to be physically wrong, seek the advice of a dog trainer who uses positive reinforcement techniques, or a veterinary behaviorist, to help curb this behavior. If left untreated, Lady may injure our other dog, a person or another animal. I would advise keeping her on a leash and away from other animals and people until you have the chance to work with a trainer or behaviourist, and keep her in a separate room from your other dog. You may need to muzzle her to prevent injury. Visit the following link for more information on dog behaviour issues. http://www.dacvb.org/resources/for-the-public/ .