Feline Behaviorist Pam Johnson-Bennett is the author of a number of award-winning and critically acclaimed books, including Think Like a Cat and Psycho Kitty. The innovative methods described in all her books are based on Pam's unique way of training by actually understanding the way a cat thinks. She makes numerous television appearances including CNN, Fox News Channel, and National Geographic specials, as well as being a popular guest on many nationally syndicated radio programs. She is now considered to be one of the leading experts on feline behavior.

Q: My husband and I have two cats, Nala (female, five years old, spayed) and Mo (male, four years old, neutered). Mo came to our house as a little kitten and Nala was already there. When he was little, Nala used to groom him and love him, but as he grew older he started attacking Nala at her neck, (even though he had been neutered already) and takes hair off her body. She just runs away and cries but won't attack back or defend herself. When we are around we protect her, but if Mo is there she cannot go anywhere on her own because he would attack her. When we leave they have to be left in different parts of the house, or else Mo will attack Nala and won't let her eat or go to the bathroom. When Mo is sleeping or outside on a walk she still looks around and is nervous of walking around. When we see he is going after her, we get behind him so we can protect Nala. Can we still solve this problem? How can we help Mo be nice to Nala so that if we are not around she won't be threatened? How can we make them get along?

A: Although it can be upsetting to cat owners, it's not unusual for shifts in the hierarchy to occur as cats mature. As Mo has gotten older, he has become the dominant cat. Also, cats reach social maturity (not to be confused with sexual maturity) anywhere between two and four years old, and major shifts in the pecking order can happen around those times.

Since the behavior is serious and ongoing, the best way to handle this is to completely separate the cats and do a total reintroduction -- as if you were bringing Mo into the house for the first time as a new cat.

Let Nala have the run of the house and separate Mo into one room. It's good for Nala's confidence to have the prime areas of the house to herself during the reintroduction.

Gradually let the cats begin to see each other for short periods. Keep everything positive by offering treats whenever they are in each other's presence. This is how they start to form positive associations with one another. Initially, the sessions may only last 30 seconds, but you can gradually build up the time. If the cats aren't motivated by food, you can keep interactive (fishing pole) toys handy to distract them while together. This way you can start to break the ongoing behavior pattern.

I would also suggest you use Feliway in the environment. This is a product that contains synthetic scent chemicals from a cat's face. These scent chemicals, which are known as pheromones, have a calming effect on cats. You can get the product at pet supply stores and it comes with instructions.

Don't let Mo attack Nala. Whenever you see him starting to stalk her, divert his attention toward an interactive toy. This will help both cats become comfortable with each other again.

Finally, make sure you have enough vertical areas in your home for the cats. You can create this by having cat trees, window perches or cozy elevated beds on various pieces of furniture. The more high resting places you create, the more territory you'll create for each cat. Also, you should have more than one litter box (in separate areas of the house) and two feeding stations. This will help decrease tension so the cats won't have to share.