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Animal Health Foundation Animal Health Foundation
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Aggressive behavior in cats isn't always obvious to owner

There are more cats living in American households than dogs, and they usually don't live alone. Most cat homes have multiple cats. When cats don't get along, that is a source of stress for the cats as well as their owners.

The top two reasons for cats being relinquished are aggression and elimination problems, and sometimes the two can be intertwined.

Almost all acts of aggression between cats are resolved without actual fighting. Cats are subtle, and a lot of behavior can go unnoticed by owners. Stress can build over years and suddenly erupt into a huge problem. Watch for these subtle signs of brewing aggression:

» Staring can be a common form of aggressive display. Watch for the other cat's behavior in response to staring. Do they stop what they are doing? Do they turn around? If so, then this staring is a form of control one cat uses over the other.

» Choice of resting spot can be a clue to what is going on. Often, an aggressor cat will lie in open areas that allow them access to important resources such as food and water bowls, litter boxes or access to outdoors. These cats may appear at rest, but their ears may be partly pinned and their tail may be switching or flicking.

» Change of behavior on the part of the recipient cat. Cats that are the receiver of daily stressful communications can show changes in weight, grooming behavior and litter box habits. They may startle more easily and change where they prefer to lay, sleep or play based on the behavior of another cat. These are subtle signs of avoidance. Sometimes, these cats become exclusively active at night when the other cat is not.

Owners typically notice a problem when their cats are actually fighting. Hissing, chasing, clawing and biting are usually obvious signals that there is a problem. Sometimes, owners misconstrue this behavior for playing. A good question to ask when trying to distinguish this is: "Does the recipient come back for more?" If there is no give and take, then it is probably not play. They might also notice when one or more cats experiences a litter box problem. Hiding and avoidance can play into why especially victim cats may start to inappropriately eliminate. This problem is inextricably intertwined with healing the rift between the cats.

Owners often are misinformed that aggression between cats is a problem that cannot be solved. Treatment of inter-cat aggression is highly individual to the cats involved but is something that can be resolved well. Ideally, it is best to work on the problem before it progresses to more serious displays of aggression.

If you see warning signs of aggression between your cats, don't wait to get help from your veterinarian or an animal behaviorist. There are many more choices for treatment when the cats are not aggressive onsite. Cats can live together in harmony.

Dr. Jennie Willis is an instructor of animal behavior at Colorado State University and owns a private consulting business, which provides counseling for problem pets and their people. For more information about consultation, seminars and classes please visit

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