Is a Yorkiepoo Chihuahua mix dog prone to aggression like Chihuahuas?

Yorkies can be somewhat protective, as all terriers can, however they don't have a reputation for being aggressive. I'm assuming your considering getting a Yorkie puppy, and if so you can get her off to a good start by selecting a breeder that takes measures to properly socialize the puppies before they leave their mother. This includes exposing them to humans of all sizes, so that they are comfortable with people. As soon as your puppy has had all of his/her puppy shots (16 weeks) you can enroll in a "puppy kindergarten" class, and this helps to establish good behavior and manners from the start.

Aggression can have many different causes, with fear being the most common. If it started at 5-6 weeks of age, I can almost guarantee something is deeply wrong with her brain because that's very abnormal. Sadly, after 4 years of practicing the aggression, it's going to be hard to change her behavior. I would recommend starting with a consultation with a veterinary behaviorist (not a trainer or non-veterinarian) who can diagnose the problem, prescribe medications, and start behavior modification with you. Good luck!

Chihuahuas are loving devoted dogs when properly trained. They can be protective, and aggressive if spoiled, not socialized or have not had obedience training. I would not recommend this breed for a new dog owner or in a house with small children, since they often will bite and can be stubborn. They also can have some medical issues such as luxating patellas and sometimes back problems. One of the best personality small dogs is a Shih Tzu. They are great family dogs, are affectionate and live a long time. They do need to be groomed though to keep the coat from matting. Many people clip them to keep the fur short and manageable. I'm glad you are researching dog breeds before you get a dog to make sure it is a good match. Thanks for using Petco Pet Education Center, formerly Petcoach to help you get answers to your veterinary questions.

Thank you for using Petco Pet Education Center, formerly Petcoach, and congratulations on your new puppy. I'm glad she is playing and sleeping with your 2 older females. While sometimes dog behavior can change over time, there is nothing to say that she will for certain become aggressive with age. As they grow out of the puppy stage, they can try to establish dominance among the other dogs, but this doesn't always happen, and only time will tell what your girls will do. Hopefully, Peaches will continue to leave in harmony with the older dogs.

There is no guarantee with any breed, but being raised together can help. Just make sure you are always there when they play that way you can intervene and correct whoever is being too rough. generally the smaller dogs are usually in charge anyway

I'm afraid it's hard to say why Prince might be acting aggressive without more information - aggression in dogs can have many different causes. Some common possible causes for aggressive behavior would include fear/anxiety, stress, resource guarding, frustration or over-arousal, or playful biting and mouthing which some owners interpret as aggression. Feel free to post another question with more details, or request a one-on-one consultation with one of us for a more in-depth discussion about your concerns if you prefer - we would be happy to try and help.

It may be a little bit of both. I believe that a lot of aggressive behaviors can be prevented by the way the puppies are raised, but there are possibly heritable traits that could be passed along with breeding. I would avoid breeding aggressive dogs.