Aggression in cats has been recognized as the second most common feline behavioral problem seen by veterinary behavior specialists (Curtis, 2008). It is a very complicated and upsetting problem to the owners not only because of the patience, commitment and efforts needed to manage it but mainly because the problem poses direct implications for the welfare of the cat and can dramatically affect the cat-owner relationship with the potential for ultimately leading to relinquishment of the cat. There are also public health concerns given the relatively high risk of zoonoses from cat bites and scratches.

Most owners expect their veterinarians to have feline behavior knowledge in order to be able to advise them on how to deal with their aggressive cats. Thus veterinarians are in a unique position to help manage feline aggression problems and this process should start by an exclusion of any underlying medical condition and a detailed collection of the behavioral history.

This presentation will focus on the various aspects of feline aggression seen by the owners in their homes with a step-by-step approach to behavioral diagnosis and treatment of common types of both 1) human directed aggression and 2) intercat aggression.

1. Human Directed Aggression

Bradshaw and colleagues (2000) in a door-to-door survey of cat owners reported that 13% of owners declared that their cats showed human directed aggression. In another more recent survey carried out in Brazil, human directed aggression was perceived by about half of the cat owners who answered a questionnaire (Ramos & Mills, unpublished data). Thus, human directed feline aggression seems to be more common than currently recognized.

Defensive and offensive displays of feline aggression can be seen in response to people. Aggression when stroked or petted is reported to be the most common form of aggression shown by cats (Blackshaw, 1988; Ramos & Mills, unpublished data) against people. Other frequently reported types of human directed feline aggression are: fear or defensive aggression, play and predatory aggression, assertive aggression, redirected aggression and pain-related aggression.

Lack of early socialization in particular gentle handling (Turner, 2000; Lowe and Bradshaw, 2001; McCune, 1995), mother's absence during socialization (Rodel, 1986) and paternal temperament (McCune, 1995) have been reported to increase the risk of aggressive behaviours towards people. Other factors such as gender, neutering, access to outside, home environment, early trauma and living with other cats have just started to show their significance in more recent studies (Ramos & Mills, unpublished data) but still deserves deeper investigation.

The selection of the treatment method for cases of human directed aggression will depend upon the form of feline aggression dealt but it will mainly consist of a multifactorial approach of behavioural modification and environmental changes. Antianxiety medication such as benzodiazepines (e.g., oxazepam), tricyclic antidepressants (e.g., clomipramine) or selected serotonin reuptake inhibitors (e.g., fluoxetine) can be added as an adjunct to the treatment plan. "Pheromone" therapy may also be of help in some cases. The use of other more recent studied compounds such as some neutraceuticals (e.g., alpha-casozepine, l-theanine) may be useful in cases of anxiety based human directed aggression (e.g., from fear).

Prognosis will depend critically on the potential for injury and the ability and willingness of the owner to implement the treatment proposed.

2. Intercat Aggression

For the purpose of this presentation, intercat aggression will be used to describe aggression between cats living in the same household; thus, aggression towards and/or from outside cats will not be included in here.

Intercat aggression within the home has been understudied despite its high prevalence. According to the survey by Bradshaw and colleagues (2000) 48% of the cat owners reported their cats showing aggression towards other cats. This is in accordance with a survey of 887 owners at veterinary hospitals in the United States in which Borchelt and Voith (1987) concluded that cats are more likely to direct aggressive behaviours towards another cat than towards humans; however one recent study (Amat et al., 2008) has found that when access to the primary target is denied, the owner is most commonly the target for redirected aggression.

Aggression in multi-cat households can occur in a variety of contexts, ranging from an occasional chase to intense fighting (Crowell-Davis, 1997). It is commonly seen as a result of the addition of a new cat into the home or due to changes in the composition of the social household (e.g., death or absence of a resident cat, change in a resident cat´s physical appearance, deterioration in a cat´s condition as result of aging). Another common scenario refers to cats that used to get on perfectly well with each other but start to have aggressive encounters once one of the cats (or both) reach social maturity (Juarbe-Diaz, 1999). In all of these scenarios (and in other less common contexts) cats can display different forms of aggressive behaviour depending upon their motivation as well as their emotional status (e.g., fear aggression, territorial aggression, play and predatory aggression, redirected aggression, assertive aggression and pain induced aggression). Dominance aggression can be seen as one cat bullying another (Beaver, 2004).

Research by Lindell et al (1997) showed that male cats initiated aggression in more cases than did female cats, however the aggression was equally likely to be directed toward a same sex or opposite sex victim. Levine and colleagues (2004) found that neither age, sex, nor number of cats in the household was associated with current fighting. But their studied revealed that current fighting was associated with certain behaviors (i.e., scratching and biting) during the cats first meeting, outdoor access and the owner´s perception of the first meeting as unfriendly or aggressive (Levine et al, 2004); thus pointing out the importance of gradually performing introduction of new cats within the home in order to prevent aggressive displays during first meetings.

Treatment for inter-cat aggression includes the conjunction of behavioural modification, environmental changes and medication for the aggressor, for the victim or sometimes for both of them.

References

References are available upon request.