Feline Territorial Aggression

Filed Under: Cats, Behavioral & Training

Territorial aggression involves displays intended to exclude a cat from a particular area and often occurs when a new cat is introduced into a household. Individual cats may vary in their tolerance of other cats in the home. The introduction of a new cat to the household is easier when at least one of them is a kitten or juvenile. Assimilation is also easier when all the felines are well socialized to their own species. Cats that lack social skills will not understand normal feline communication and etiquette and will likely have inappropriate or exaggerated responses to the introduction of an additional cat. Bottle-fed kittens that have never been around others of their own species may be especially challenging, if not impossible, to socialize. Bottle-fed kittens do not realize they are a member of the feline family.

Members of a feline family tend to be insular social groups that are distrusting and unaccepting of strangers. Cats within the family may act aggressive to one cat while being tolerant or friendly to another, and it may not involve solely the newly-introduced family member. With a new cat’s introduction, suddenly the whole family hierarchy may need to be reshuffled. Territorial aggression becomes a problem when the victim of the aggression is being injured or becomes so fearful that it continually hides to avoid being attacked.

Aggression may be prevented or at least lessened in intensity by facilitating the introduction of a new feline member to the household. Initially, cats should be separated and then gradually exposed to each other under nonaggressive circumstances such as during feeding and play. Cats may be fed or played with on opposite sides of a barrier such as glass followed by a screen door that is the gradually removed. This gradual introduction allows the cats to get used to the sight, sounds, and smell of each other before meeting directly. The cats may be separated in different rooms when a physical barrier is not available and even bedding may be alternated. Alternating rooms and bedding allows the cats once again to get used to each other’s odors and sounds without visual or physical contact. The exposure should be gradual and take place over a period of weeks and may still not be successful.

An alternative method of introduction may be through the use of opposing kennels which may be placed on opposite sides of a room and are gradually brought closer and closer together. With this option, it is important that the felines are kennel-trained, for if either cat is uncomfortable in a kennel situation it will only add to the stress level of those involved.

It is generally considered that acceptance of a familiar cat is far more likely than that of a totally unfamiliar cat. Younger cats and kittens tend to be far more accepting of a new introduction than an older established individual. In some cases, a male will be more accepting of a female and vice versa.

During the final stage of a new introduction, harnesses, leashes, and human handlers may facilitate the direct physical contact. Each cat should be counter conditioned through what activity the cat likes best, such as treats, petting, or play. Contact should be gradual and the distance may be continually decreased, unless hostilities break out. Mechanical restraint may then be achieved should a fight erupt and the process may be repeated at a later date. Eventually the restraints may be removed and the cats allowed to interact freely.

The aggressor may not necessarily be the oldest cat or the cat that has been living in the house the longest. This type of aggression may also occur between cats that previously coexisted peacefully once another cat has been introduced or has reached sexual maturity.

Territorial aggression is difficult to treat and is not typically amenable to drug therapy. A new pheromone product approved for the decrease of stress between cats may be of assistance. Feliway® spray, also available as a plug-in device, may prove helpful in easing an introduction. The product professes to mimic facial pheromones that give the cat a feeling of well-being, thereby eliminating stress and improving the chance of a successful introduction.

In certain instances the only solution may be to find another home for one of the cats or to keep the opposing cats separated at all times, one indoor and one outdoor, or each cat may be confined to differing house areas.


Beaver, Bonnie. Feline Behavior: A Guide for Veterinarians. W.B. Saunders Co. 1992. Pp. 97-115.

Crowell-Davis, Sharon. “Intercat Aggression.” Compendium for Continuing Education Veterinarian. September 2007. Pp. 541-546.

Horwitz, Debra. “Feline Aggression Directed Toward People.” NAVC Clinician’s Brief. May 2007. P. 33-34.

Marder, Amy and Victoria Voith. “Advances in Companion Animal Behavior.” Veterinary Clinics of North America. Vol. 21. No. 2. W.B. Saunders Co. March 1991. Pp. 315-327.

Topics: aggression

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