If the fur’s flying in your house, the result can be cat-astrophic! Seriously, though, once your cats start fighting, it is unlikely to resolve on its own and you do need to intervene before serious injury to the cats, or you, occurs.
Firstly, we need to look at why the aggressive behaviour is occurring and, secondly, who is the aggressor and who is the victim?
Territorial aggression in cats is common. Often the aggressive behaviour is triggered when a new kitten or cat has been introduced into the household and upsets the status quo. Cats do not like change! This is more likely if one or both has had inadequate socialisation with other cats as a kitten, or when there are just too many cats for the amount of available space.
Sometimes it occurs between two cats in the household that have previously got along well, or you haven’t noticed any overt stalking, chasing or fighting. Aggressive behaviour can be quite subtle in cats, such as blocking access to food, litter trays, rooms or stairs. You’ve probably seen videos of dogs scared to enter rooms or climb/descend the stairs when the resident cat is sitting there nonchalantly?
Covert aggression might not be as noticeable with cats, but look for one that slinks away when the other approaches or doesn’t enter a room where the other cat is. It might be losing weight or not-using the litter tray because it can’t access these resources. The victim cat might perch up high or hide a lot, its coat looks unkempt or is losing hair because it is constantly grooming itself. This cat is a victim and is quite miserable.
Sometimes when young cats in the household reach social maturity at around 1-2 years of age, fighting can start out of the blue when one feels the need to declare its territory inside the house and to show its superiority.
Another situation where aggression can occur between two previously friendly cats is the removal of one, say for veterinary treatment or surgery, and on its return it is attacked, perhaps because it smells, looks or acts unfamiliar in some way.
A behaviour known as 'transferred aggression' often occurs, too. A house cat can be upset by seeing a roaming cat travelling through its garden. The resident cat becomes frustrated that it can’t chase the cat away, over-aroused or even fearful and attacks whoever is nearest at the time, often its house mate or even its owner!
Will my cats ever get on again?
Once overt fighting occurs between cats, they can stay aroused for hours or even days. Cats tend not to forgive and forget! If you have enough resources for the cats and the behaviour has only occurred a few times, the cats may resume being bosom buddies if you’re lucky. More commonly, peace returns but they lead completely separate lives, seemingly oblivious to each other’s existence (with perhaps the occasional hiss and spit).
However, it may not resolve at all and the cats cannot be in the same room or house or even the garden together without fighting. Injuries are common and, in this situation, the cats must be separated from each other for their safety.
What can be done to solve cat aggression?
The first step is to separate the cats for a few days. This will prevent any further aggression and thereby stop what is called self-reinforcement of this unwanted behaviour. It gives the cats a chance to calm down, too.
When they are re-introduced the aggression may not show again but usually this is not enough to solve the problem.
What we need to do is change the cats’ feelings towards each other from a negative one to a positive emotion through a process of desensitisation and counter-conditioning. Desensitization involves exposure to the other cat but at a low enough level that either cat does not become fearful or aggressive.
Counter-conditioning is used to change the cat’s response to the other cat by associating the cat’s favourite treats with each exposure. The cats are then slowly introduced to gradually more intense stimuli (e.g. closer) paired each time with the presentation of the highly-favoured reward.
10 Steps to Re-Introducing Your Cats
Firstly, separate the cats by confinement behind a common solid door until the cats adapt to the odour and sounds of the other cat and show no fearful or aggressive responses.
Placing a towel with the cat’s scent in the other cat’s confinement area can assist the cats in getting used to each other without having to see each other. Gently rub a slightly damp and warmed face-washer or handtowel around the face and cheeks of the victim or least aggressive cat first. Then take it to the more aggressive cat and do the same. Make it a happy experience by offering a very special food treat before you begin towelling. Take the towel back to the first cat and give it a rub once more. This has allowed the cats to share their scents or pheromones, which are powerful chemicals that cats use to communicate with each other.
After a few days or even a week, the next step is for the cats to see each other through a glass or mesh door, which allows for safe visual exposure. If the cats are happy to see or sniff each other through the mesh without friction, then you are progressing well. Allow them to sniff each other for a few minutes each day and give the cats a treat with each exposure to create a positive association.
Can they be in the same room? This time place each cat in a cat cage and put the cages in the same room at a sufficient distance that they show no fear and will take treats. The cages can gradually be brought closer and closer to each other while the cats' happy moods are maintained.
The next step is to allow one cat free. Place the least aggressive cat in its cage and allow the other cat to roam free in the same room, preferably a neutral room that has no special significance for either cat. Toss some treats gradually closer to the other cat’s cage. If all goes well, the roles can be reversed with the tough guy in the cage and the other free. Again you may need to test the water like this for a few days.
Now it’s time for both to roam free. A leash and harness on each cat is recommended for safety. Have one person with each cat and giving it treats as it gradually gets closer to the other. If one or both cats do not eat, move them further apart. If things go well, the cats can be moved slightly closer together during subsequent conditioning sessions.
Progress slowly! Allowing either cat to become fearful or aggressive sets the program back. The cats must remain separated except during the counter-conditioning sessions. When the cats appear ready for some freedom to roam the home, it might help to place a bell on the more aggressive cat to help you supervise and so the other cat knows when it is near.
Anti-anxiety medications and ‘happy’ pheromones e.g. Feliway may be useful during a behaviour modification program to reduce apprehension and allow the cat to learn pleasant associations. Feliway Spray can be sprayed onto the cat’s cages and the Feliway diffuser plugged into the room the cats are meeting in.
In any situation where there are multiple cats, it is important to allow as much space for perching, climbing and hiding throughout the house as is practical, and maintain separate feeding and litter stations to reduce conflict.
What if they still fight? For serious cases of aggression between cats, it is often useful to get the cats out of the home and re-introduce them in a foreign location where neither has territorial rights, such as a cattery or veterinary surgery. If this isn’t successful, then as a last resort you may need to consider rehoming one of the cats.