How to transition my dog-aggressive dog to apartment living safely?

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.

In addition to a gradual introduction or acclimation, consider using a pheromone product such as the Adaptil collar or DAP plug in diffuser. Either may decrease any anxiety or aggression. Correct any aggression or negative behavior immediately. Praise and reward good behavior. Be consistent and be patient.

This can be a very frustrating situation. Typically Lady is feeling threatened and possessive leading to aggression. I would highly recommend hiring a behavioral trainer to come into your house and help work through Lady's behavior. You can try adaptil a pheromone to help reduce stress and even increased exercise can help with anxiety but a trainer is the best option.

Have her spayed. This will decrease hormones which can drive certain behaviors. Slowly acclimate Panda to one dog, then another and another. Do this on "neutral" ground and on leash. Correct any aggressive behaviors immediately. Use praise and small rewards as she progresses. The use of a pheromone product, such as the Adaptil collar, may also help to ease her anxiety/aggression.

Any introduction should be done gradually and on "neutral" ground. You can use a pheromone product such as an Adaptil collar to decrease anxiety or aggression. Introductions should start with Max being able to hear and smell a new dog but not see him. This can be done a friend's house or perhaps a family member's home. Again, some place neutral to both dogs. Once he is acclimated, he should be able to see the new dog but have no physical contact. This can be done using the fence at a dog park. Eventually, you will be able to physically introduce Max to the dog. Use a leash on both dogs for safety and muzzles if necessary. Go slowly, don't force him but correct any negative or aggressive behaviors immediately. Praise and reward him as he progresses.

Give him some time to acclimate. A pheromone product, such as the Adaptil collar or DAP plug in diffuser, may decrease any anxiety. Consider short visits to a dog park or short walks to get him further acclimated. Praise and reward him as he progresses, but correct any negative behavior immediately. If you need help, consider an obedience or socialization program. The local Petco may offer one or both.

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.