The tiny, six pound Chihuahua was bred to be a companion animal, but some Chihuahuas can be temperamental and show signs of aggression such as growling or biting. There are several different reasons that Chihuahuas become aggressive, but the problem should be dealt with regardless of the reason. A bite from a six pound dog may not seem as serious to you as a bite from a 60 pound dog, but the aggression can still be a dangerous problem for both you and your headstrong Chihuahua because people may press charges, or your Chihuahua might pick a fight with a much larger dog.
One of the first things you should do if your Chihuahua starts to show signs of aggression such as growling and biting is take it to the vet for a checkup. Just like you might be cranky when you don't feel well, your Chihuahua can show that it is sick by acting aggressively. Make your Chihuahua an appointment with your veterinarian to ensure that the aggressive behaviour isn't caused by pain or illness.
Chihuahuas need to be socialised from a young age. When you introduce your Chihuahua to new situations, people and animals, you teach it how to handle new experiences in a calm manner. Socialisation builds confidence, and confident Chihuahuas don't feel the need to respond to new situations or new people with aggression. If your Chihuahua feels uneasy around strangers or in new surroundings, it may growl and bite.
A dog's primary means of self-defence are its teeth. When something frightens or startles your Chihuahua, it may respond with a growl, snarl or snap. Observe your Chihuahua to see if its aggression corresponds with certain stimuli, such as thunderstorms, the presence of larger dogs or visits from strangers. If your Chihuahua only behaves aggressively in certain situations, it may be exhibiting fear-based aggression.
Some Chihuahuas can become dominant and will growl, snap or bite to let you know that they are in charge. Dog Breed Info Center refers to this as "Small Dog Syndrome," which can occur when the owners of small breeds don't give their small dogs the same training or boundaries they would give a larger dog. Regardless of size, your Chihuahua's aggression is still aggression. It shouldn't be encouraged or justified as being "cute" or "funny." You can avoid this type of aggression by setting rules and boundaries for your Chihuahua. Don't allow your Chihuahua to put its paws up on you when you walk in the door. Don't let it in the kitchen while you cook. Choose any rules you would like, but enforce them consistently to let your Chihuahua know that you run the house.
Chihuahuas can be territorial dogs. They may show aggressive behaviour in an attempt to assert their ownership of a particular object, place or person. Because Chihuahuas are "one-person dogs," meaning they often attach themselves to a single individual, they may growl or snap when anyone else comes near "their" person. Chihuahuas may also bite or growl to protect their food, their bed, their toys or their bones.