My dog growls at our new, larger rescue. How can I prevent fights?

This is not unusual behavior as they are trying to work things out. I recommend to always supervise them together until you know there is not chance of a fight. Some dogs are more possessive of toys or food or their person and thats just how they are. Certainly not leaving toys down and only giving them toys when you are home to supervise will help. Do not allow them to steal each other's toys. Also, both dogs will likely think ALL the toys belong to themselves and not the other dog. If you cannot supervise then, you may separate them during chew times with their toys. Heavy daily exercise will help to get some of the energy out and this can help to decrease aggression. I also recommend to pick up some books about dog behavior so that you can recognize what the dogs are saying to each other. Lastly, there are several different training methods out there. You may opt to find a trainer who can come to your house and show you how to modify the dogs' behavior. Find a trainer who's style works with yours. This will take some time to condition the dogs and yourself. I hope this at least points you in the right direction. Please post again with any further questions.

This behavior is likely to improve with time. Take them on leash walks together frequently (twice a day if at all possible). Feed them in separate rooms, as this is the time he is most likely to actually snap at her. If his behavior is not improving, consider keeping a [basket muzzle](https://www.petco.com/shop/en/petcostore/product/baskerville-ultra-black-muzzle-for-dogs) on him when they are inside so he can't hurt her. Also, if his behavior isn't getting better, ask your vet for a referral to a trainer or behaviorist who can help you. Thanks for asking PetCoach!

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.

Your house is a lot different, and your own dog may be feeling like there is a bit of an "intruder" situation going on. it may take some time for your dogs to all get along, especially if the change was recent. Until they get along better, the dogs should only be together when able to be supervised by you. You may also want to pick up items of contention such as beds, toys, treats, etc that may be fought over if your dogs feel threatened. If a fight breaks out, immediately separate the dogs for a "time out"/cooldown, and then reintroduce when all dogs are calm and relaxed. When you are not at home, the dogs should be separated or crated in separate crates to avoid a potential fight. If the issue persists, speaking with a trainer or behaviorist may also help as they can often observe what is going on in the home, and can make suggestions based on your specific needs.

I'm sorry to hear that you're having these problems! Aggression or fighting between dogs in the same household is a complex behavior issue that's very difficult to address without evaluating the dogs in person, because there are so many factors to consider - it's important to assess both dogs' personalities, how they interact with each other when they're not fighting, how severe the fights are when they happen, what seems to trigger the aggressive behavior, etc. For this reason, I would strongly recommend getting in touch with a veterinary behaviorist or a good reward-based trainer who can work with you in person to help determine why the aggression is occurring and put together a detailed treatment plan to address the problem. In the meantime, I would recommend keeping the younger dog on-leash whenever he is around the older dog to prevent any bullying or harassment, or using a baby gate or other barrier to keep the dogs separated until you are able to get some hands-on guidance in how to help them.

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.

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.