For cats, territory is extremely important. Owning territory gives them the ‘rights’ to that space, including food, shelter and safety. There are responsibilities to owning territory, keeping the peace, marking the boundaries, defending against intruders. Human carers are considered ‘high value’ territory.
While many cats are prepared to share part of their territory with others there are some that are not even prepared to consider that as an option! Often these cats lack confidence or have not had ongoing contact with other cats. Personality also plays a role in relationships.
Territorial aggression occurs when one cat feels that another cat is, or could, encroach onto his territory. When the defended territory is the carer we may refer to a vat as being ‘jealous’ when in fact he is keeping his ‘territory’ safe from invasion. Losing complete control over his carer could mean that he no longer receives all the benefits of food, shelter, safety and care. This behaviour is typically towards other cats but may be against other pets or animals or people.
Some causes of territorial aggression are the introduction of a new cat, sexual maturity of one cat, illness or injury making a cat defensive, changes in the human family, changes in the environment, or other triggers such as non-family intruder cats on the territory. Cats that have previously been friends can turn aggressive. See Redirected Aggression
This type of aggression often begins slowly and subtlety and can escalate into full-scale war between cats that were friendly. The protecting cat will show signs of aggression by hissing, growling, puffing up his fur and posturing. If the threat persists he will lash out and then attack. This can escalate into one cat chasing, and later even hunting out, the presumed aggressor even when the territory is not under dispute. Spraying and urine marking are often used as territory markers. Where cats do not have sufficient other stimulation, are bored, stressed or not socialised to other cats, this can become a habit that is difficult to break.
The first steps in resolving this form of aggression are a full vet checkup for both cats, identification of the territory or resource that is in dispute and establishing which cat is the aggressor; usually the one who initiates the attack.
Separate the cats and keep them in separate areas with all the necessary items, food, water, litter trays, toys and stimulation. Ideally neither of them should have access to the territory under dispute, although this can be difficult if this is the carer.
Use natural or homeopathic calming remedies to reduce stress and tension in both cats. In extreme cases it may be necessary to use medical calming medication available from your vet.
Once both cats have relaxed and are calm, begin the process of introduction as if they were new cats meeting for the first time. The cats will determine how long this process takes, which may be longer than the original introduction. Many cats will learn to accept and live reasonably peacefully with another cat, even if they do not become friends. In extreme cases it may be necessary to re-home one of the cats; this should be a last resort.
Punishing any act of aggression will only escalate the behaviour. Aggression is a normal reaction to a trigger that is anticipated and accepted by other cats.