Ideally, the program should be designed and carried out in such small steps that the problem behavior never occurs during the program. This means that all the stimuli that cause the behavior should be identified and that you should find a way to lower their intensity until your pet doesn’t react to them. For example, if a cat becomes afraid if someone approaches closer than six feet, then the starting point would need to be much further away than six feet.
Determine what is provoking your pet's reaction
For example, if a cat is afraid of being picked up, you would want to figure out exactly what she's scared of. Is she more afraid of adults than children? More afraid of men than women? More afraid of a family member or someone she doesn’t know?
Some common factors to consider include location, loudness, distance, speed of movement, length of time near the other animal or person, response of the other animal or person, and body postures of the animal or person who induces fear or aggression.
Arrange these characteristics in order from least to most likely to produce a negative response
A counter conditioning and desensitization program needs to begin by using combinations of stimuli that are least likely to cause a fearful reaction. In our cat example above, perhaps the cat is least afraid of being handled by a familiar adult female who approaches slowly and speaks softly to her, while she’s lying on the bed in the bedroom. She is most afraid of a nephew who runs up to her yelling while she’s in the kitchen.
Begin with the characteristics that are least likely to elicit the problem behavior
Begin with the easiest combination of characteristics of the situation, and gradually work up to the most difficult. If a cat will be less afraid of a male child approaching slowly than an adult female approaching fast, then we know speed of approach is more critical than type of person. Don’t make all dimensions more intense at the same time.
Devise ways to make each characteristic less intense
If a dog is afraid of the sound of the hair dryer, the sound must be presented to the dog at a low intensity that doesn't provoke the fearful behavior. This could be done by turning the dryer on and off quickly before the dog shows fear, turning the hair dryer on in another room, covering the dryer with towels, etc.
Pair each level of each characteristic with a positive consequence
Help your pet associate good things with the situation rather than bad things. Good choices are food (especially favorite treats), toys, and social reinforcements like petting, attention, and praise. If food is used it should be in very small pieces and be highly desired by your pet (cheese, hot dogs or canned tuna often work well). You may need to experiment a little to see what food is the best motivator for your pet.
Don't move on to the next level until your pet is clearly anticipating the reinforcement
People commonly want to know how long they need to repeat each intensity level. This will depend entirely on your pet, who should be demonstrating that he is indeed expecting good things to happen. Perhaps he looks to you for a treat, or looks around for his toy. This should be in contrast to his previous reactions such as trembling, tensing up or other fearful or aggressive responses.
Counter conditioning and desensitization take time and should be done very gradually. Think through the steps you need to take. Rather than expecting progress in leaps and bounds, look for small, incremental change. It can be very helpful to keep a record of your results, since day to day changes will not be very big.
You may need to supplement the behavior modification program with other approaches, such as avoiding situations that provoke the problem, using a headcollar like the Gentle Leader collar or treating your pet with anti-anxiety medication. Your veterinarian or an animal behaviorist can give you more information on these options.