How to train my adopted Chihuahua mix to stop barking too much?

Introducing a new dog into the house can certainly pose some challenges. Female/female dog pairings have a higher rate of problems than male/female dog pairings. Initially, keeping the dogs in separate rooms with a solid door between them can be beneficial. Allow them to smell one another under the door for a few days, then use an open barrier, such as a baby gate between them. This will allow them to see and smell one another without direct contact. A slow introduction can ease the transition. If both dogs are food motivated, try giving each a small treat at the same time. Avoid giving a larger treat that the dogs would need to put down to chew as this could create additional problems. Hope this helps!

I am sorry to hear of your loss. It may be best to consider adopting a slightly older (1-3year old) female rather than a puppy in order to ease the transition. IF Buster is generally dominant, a more submissive type may be best. Ensure you can take Buster to meet her in neutral territory before you commit to brnging her home

What cuties!!! I would honestly be less worried about bringing a friendly adult dog into your house than a puppy because puppies can be overwhelming to adult dogs who are not used to them. They are hyper and jump and bite/chew on adult dogs and some dogs do not respond favorably to this (others are find and will give the puppy warnings or love playing with them). A great option in these cases is asking if you can do a trial run/foster for the new dog to see if they get along with your dog. This gives you a little time to make a decision. If your dog has been around other dogs without issue and this dog gets along with other dogs, then it is definitely worth a try! Make sure your current dog has the ability to get away from this dog if it is annoying/pestering her, do not leave them alone together initially, and feed them in separate areas so there is no fear of competition for food. Give your dog lots of praise and treats when she meets the new dog. Sometimes meeting on a neuteral ground can be helpful if your dog is defensive of your home. I would also consider getting an Adaptil collar or diffuser which can help both dogs with any anxiety https://www.adaptil.com/us/Products/ADAPTIL-Calm-On-the-go-Collar

Male and female combinations may get along better BUT many households have single sex pets and absolutely no problems. The biggest factor is individual personality. I recommend to have your first dog meet any potential housemates to make sure they seem to like each other. I hope this helps and please feel free to post any additional questions.

Without knowing how Cookie interacts with other dogs, it would be hard to say. I would recommend bringing her to a local park to see how she reacts- is she interested? Does she want to play? Or does she avoid and shy away from the other dogs? This may give you some idea as to how she may interact with a new dog in the house. If you do decide to get a new dog, I highly recommend bringing Cookie with you to the shelter or other place you are looking for one. Most shelters will allow you to introduce your current dog to any potential new family members to see if they are going to get along. As for age, it really depends more on your dog's personality and that of the new dog. An older dog that is super hyper may not work well compared to a very calm puppy, etc. As with any new pet, take introductions slow. Even if they got along outside the home, they may still have some scuffles over shared items, spaces, etc. Separating the two until both are calm, and then trying again to reintroduce them can help ensure things go more smoothly during the transition.

Outside is neutral territory; inside is your previous dog's territory. There isn't much other than allowing him time to get used to having a new roommate. Try to keep things as normal as possible. Continue the walks outside so they can bond. You can also use Adaptil diffusers or DAP collars to provide calming pheromones.

it is important to remember that Chico was there first, and is used to a certain level of attention from you. This newcomer has no expectations, so be sure to dote on Chico as much as ever so he feels secure. Then, gradually, you can increase the amount of time you give the new guy (without taking anything away from Chico). The second issue you are facing is that the dogs have to sort out, for themselves, who's who at the zoo. In other words, they may have one order of inportance to you, but they need to determine amongst themselves who's top dog, who's in the middle, and who's on the bottom. There may be a bit of snapping and barking going on, but as long as there are no injuries or serious fighting, leave them to it. Once they get it squared away, everyone will know his place in the pecking order and will (usually) behave accordingly.