While failure to use the litter box(s) will probably always be the number one reason pet parents seek cat behavior help, aggression is next on the list. Whether life-long aggression or that of sudden onset, as loving as your ‘Mad Max’ may usually be, those flying claws and sharp teeth mean business; people, other pets (and even Max himself) can get hurt.
If you take the time to ‘read’ your cat, you will see that Max is sending you plenty of signals that something is wrong. Aggression is harmful or threatening behavior towards a human, another pet or any other animal and can be displayed as:
Offensive stance or posturing: Max makes himself look as large and scary as possible. His ears are upright, tail lowered and stiff; fur on his tail is erect. He is facing the threat, may even begin moving towards it. He may be growling, his pupils constricted, eyes staring.
Defensive pose and movement: Max anxiously makes himself as small as possible. His tail is curved and tucked in, he is crouching, ears flattened; his whiskers may move forward and his body is turned sideways not head on. He may spit or hiss.
Do not try to comfort Max; you could inadvertently reinforce this behavior. (Now may be a good time to rattle that can of coins you keep handy to distract your cat.)
Common types of aggression in cats can range from fear (when the cat has perceived a threat and cannot escape) to pain (even a docile, well-socialized cat will lash out when he is ill, hurt or in pain) and even territorial disputes. Max will defend the territory he believes is his against, humans, dogs and other cats; if he is an un-neutered male, territory issues could be to blame. In some cases, he may not know how to play properly; you may have inadvertently taught Max to play aggressively. He is not a dog and does not play like one.
Since aggression can have many causes, including pain or illness, any display of aggression is a sign that a trip to your veterinarian is in order. Working together, you can restore Max (and the peace in your home).