My dog humps and gets aggressive. How to introduce him to another dog?

The most important thing is that, if you get another dog, you introduce the two on neutral territory. Just waltzing a strange dog into Cody's house is begging for trouble. You could try a trial meeting to see how Cody is with the other dog. I would recommend a bitch, as two dogs of opposite genders are the least likely to fight. Remember that Cody was there first, and be sure he gets the lion's share of attention. Sometimes, the novelty of a new dog, and the requisites of trainng, mean that the old dog gets left out a bit. The new dog will not know you, and will therefore have no expectations as far as interacting with you. But Cody will want what he's always gotten. I don't know if Cody is aggressive due to basic temperament, or if it's a learned behavior. You can ask your vet for a referral to a canine behaviorist (different from a trainer) to help with this. Good luck!

You're right that there can sometimes be problems when introducing two dogs for the first time, especially if either of them has any history of aggression towards other dogs. I would recommend introducing them in a neutral place at first, like a park. Keep both dogs on leash, let them sniff each other briefly, then go for a walk together. This allows the dogs to get used to each other's presence without feeling pressured to interact. After the walk, take them both home and into the house together and if things are going well, let them off-leash to relax. If things don't go smoothly, it would be best to get help from a veterinary behaviorist (ideally) or a good reward-based trainer who can work with you in person. You can search for a behaviorist in your area here: www.dacvb.org or a qualified trainer here: www.ccpdt.org.

Introducing dogs should be done carefully and you must observe both dogs closely for signs of aggression or anxiety. Here are some links which may help: https://www.petcoach.co/article/5-tips-to-introduce-a-puppy-or-dog-to-your-older-dog/ https://www.petcoach.co/article/mounting-behavior/ https://www.petcoach.co/article/should-you-get-another-dog/ I hope this helps and please feel free to post any additional questions.

If there is any chance that the female could be going into heat then I would avoid this situation. While most people think they can keep dogs separated, accidents happen (dogs jump fences, etc.) and unplanned mating occurs. Whether or not they are aggressive towards eachother will really depend on each dog's personality, as many unfixed dogs will get along. Perhaps if the bitch was starting to come into heat but not yet ready to breed and the male wouldn't leave her alone there might be some problems.

It sounds like Bruno has not been socialized well with other dogs, which does tend to make it difficult to introduce him to other dogs. Try introducing the dogs in neutral territory - like a park. If it's not their house, then they will be much less likely to fight. While having the muzzle on does add security, it can make the dog act aggressive. Same can happen if you are holding the dog or putting tension on the leash. The best and safest way to introduce them would be at a neutral place with a fence inbetween them. Let Bruno off lead to explore the other dog. If he's aggressive right away, then it won't work. If he's not aggressive and seems interested, then the next step would be to introduce them while walking on lead or in an open area off-lead. This is a bit more risky, so just make sure you're nearby to break up a fight, but don't be overbearing (i.e. holding the lead tight). I hope that helps and all goes well.

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.

This definitely can be happening because Buddy is feeling uncomfortable. I would continue to have monitored meet and greet sessions, and if someone becomes too nervous or starts to try humping behavior, separate and let both dogs relax. Sometimes, dogs do well with mutual activities such as a walk or running around a backyard as this can help them focus on something else (the walk) instead of focusing entirely on the other dog. This may also help nervous dogs calm down a little by changing their focus. It does take time for dogs to get used to each other, so keeping up with the meet and greets, adding in a mutual activity, and providing places for both dogs to go and relax on their own without the other bothering them is best. I would not discipline the behavior, especially if your dogs are trying to communicate their needs to each other, and instead just calmly separate, allow them to calm down, and then reintroduce.