By Jennifer Copley (Last Updated 6 December 2011)
There are many different causes of aggression in cats, ranging from territorial defense to frustration to fear, but aggression can be a sign of illness as well.
A previously calm, gentle cat that becomes aggressive should be brought in for a veterinary check-up as soon as possible because sudden behavioural changes are often a sign of health problems. Like people, even the most good-natured cats may lash out when they’re in pain, especially if touching certain spots on their bodies causes extreme discomfort. Problems that can trigger pain-induced aggression include arthritis, abscesses, and severe dental disease. Seizure activity and hyperthyroidism can also make cats more aggressive in some cases.
There are various non-medical causes of aggression in cats as well. Petting aggression (when a cat lashes out after being petted for a certain length of time) is often caused by overstimulation. Other types of cat aggression include fearful/defensive, territorial, misdirected, inter-male, and non-recognition (for more on these, see Why Cats Fight).
When aggressive behaviour is caused by pain or illness, treating the underlying problem and the pain associated with it should stop the aggressive behaviour. However, if the cat was in pain for a long time before treatment was administered, he may have developed a negative association with being touched. In such cases, once the illness has been treated, owners may have to use counter-conditioning strategies such as providing praise and treats when the cat is touched to eliminate the negative association.
If the aggression problem is psychological, there are a number of behavioural treatments that are usually effective.
This article is provided for informational purposes only and is not intended as a substitute for veterinary consultation and care.