Chihuahuas, as well as other dogs, can be afraid of many things and/or situations. Chihuahuas are fear aggressive and will sometimes express their fear with aggression. Use conditioning training to help them overcome their fear.

Look at it from his point of view. Think about this. Dogs are expected to just deal with all the situations they are put in, whether to him they are annoying, terrifying, or intimidating. This without ever expressing annoyance, fear, apprehension, or discomfort using their natural canine communication tools. If you think about it, it’s no wonder your Chihuahua may become aggressive.
What does it mean to condition a Chihuahua?
As one expert puts it; to condition a dog is to teach him by association. When your dog associates one thing with something that he didn’t previously associate it with.
Example: Suppose you have a Chihuahua that has never eaten anything but dry dog food. You decide to start feeding him canned dog food (I don’t recommend it). The first time you open a can of dog food he probably won’t respond to the sound of the can opener at all. But after a week or so of feeding him canned dog food every day, he’ll come running when he hears the sound of the can opener. He was conditioned to anticipate the sound of the can opener.

Does your Chihuahua get excited when he hears the jingling of your keys? That’s because he has been conditioned to associate the keys with either you leaving or him getting a car ride. The same goes for when you get the leash out. My dogs all get excited when I say the word “walk”. That is because they have been conditioned to associate the keys or leash, or the word “walk” with something pleasurable. You can use this to your advantage.
Training VS Conditioning
Conditioning is not the same as training. Training involves getting your Chihuahua to perform a certain command or to NOT display a certain behavior, on cue.
Example: Training your Chi to “sit” is a training technique. Giving him praise, petting, or feeding him a treat when he performs on cue. Or taking away something he desires when he displays certain unwanted behaviors. By ignoring him or turning your back on him, for instance, are examples of training.

Conditioning is different in that your goal is not to change your dog’s behavior, but rather to change his or her “feelings” about certain things or situations. Conditioning helps to shift the emotional reaction that drives his or her behavior.
Chihuahuas And Fear
Conditioning is something every Chihuahua owner should know. As I’ve said many times, Chihuahuas are fear aggressive. If they are afraid of something, they will commonly react with some type of aggression; growling, snarling, snapping or biting.
Using Remedy as an example, I used conditioning to help her get over her fear of other dogs, especially big dogs. See Remedy’s Story, A Cautionary Tail.
She was also afraid of baths. I always bath my dogs in the sink because it is easier for me to not have to bend down to bath them in the bathtub. So I started by setting her on the counter and feeding her treats. I would do that for a short time each day for a few days. Then we would progress to setting her in the sink with no water and no running water and feeding her treats, again for a short time for a few days.

When she was calm while sitting in the sink I progressed to sitting her in the sink and turning on the water nearby, but not in the sink or too close to her and feeding her treats in the same routine. And so on, I think you get the picture. We took each “scary” thing and changed her emotional reaction to each situation. We changed her “feelings” of each from fear to anticipating something pleasurable.
Conditioning Training Tools
You can use conditioning to help your Chihuahua not be afraid of whatever it is he is afraid of. Nail trimming, baths, people, children, car rides, vet visits, etc. One behaviorist compares using conditioning along with socialization to an insurance policy. That is each time you can get your Chihuahua to associate children with treats, for example, you are ensuring that you won’t have behavior problems around children at some later time. Your Chihuahua learns that when he is around children, good things happen!

Eventually, he may learn to enjoy new experiences instead of responding with fear and aggression. Use it to help him to overcome the fear of people, noises, and new places or things. With conditioning training you don’t have to know why he is afraid of a certain experience or thing, you just need to know what he is afraid of and then condition him to like it instead.
Seeing your Chihuahua become calmer and more confident in strange environments is a joy to watch. Watching him relax and enjoy things that used to scare him is priceless.
Below is a video of one of my favorite trainers conditioning her dog Kiko not to be afraid of walking on the kitchen floor. This will demonstrate what conditioning a dog to overcome his fears looks like.