Cats are territorial and, at times, surprisingly emotional creatures. Although sometimes disturbing for us to see, it is normal for environmental or social changes to trigger extremes in our cats' behaviour. Extreme fear may provoke an explosion of hissing - a defensive behaviour, spitting, swatting and escape.
Firstly, if you have an aggressive cat, have your Veterinarian take blood and urine samples to rule out a disease such as thyroid levels.
Territorially defensive cats may stalk, yowl (also known as "caterwauling") and pounce on perceived intruders. Both fear and territorial defense may lead to visible aggression, including bites. What might cause such frightening behaviour? Most often, it is the sight, smell or sounds of unfamiliar cats outdoors.
In many cases, the source of aggression is never identified. Regardless, an extreme behavioural reaction is then bounced or "redirected" to the nearest available target: another cat in the home, or even a member of the cat's human family. Such redirected aggression is typically severe and explosive. In fact, owners frequently recount stories in which they were cornered in the bathroom for hours, waiting for their furious (and confused) cat to calm down.
Unfortunately, if not treated, such behaviour may continue for days or even weeks. Severe redirected aggression can be a dangerous problem. The cat should be examined by a Veterinarian Surgeon to rule out general medical conditions that may contribute to such behaviour.
The next steps may include temporary drug therapy to reduce the edginess contributing to the aggression. It is also helpful to separate the cat from its "victim," whether human or feline, for several days or a week. Cats that have attacked their owners benefit from temporary confinement in a dark, isolated place, such as a bathroom. Water and a litter box should be provided, but food should be offered only periodically, along with light, by the owner. Because redirected aggression can continue to be severe, this should not be attempted unless first discussed with a Veterinarian Surgeon or Behavioural Specialist. In time, many cats regain their self-control and the problem is resolved. However, caution is advised because redirected aggression may resurface the next time your cat is exposed to the same situation.