My Indoor Cats are Fighting

If you have more than one indoor cat, you have almost certainly seen them get into a scrap with each other. Almost all the time, when two familiar indoor cats fight it’s because they are playing. This is very normal behavior and is a chance for your cats to exercise and have fun.

However, that does mean some of time the fights are real and can become dangerous for your indoor cats and yourself. In these cases, you will want to separate your cats and then find out why your cats have become aggressive against each other. If one your cats has suddenly changed its behavior by becoming aggressive you should speak to your vet as this could be the sign of a health complication.  

How do I tell if my indoor cats are fighting or playing?

Play aggression is common and is reasonably easy to identify. When play fighting cats will chase each other, swat with their claws extended, bite, kick, and grapple on the floor. Biting will look aggressive, but cat skin is thick and properly socialized cats will understand how to soften their attacks to not hurt. Watch for your cat’s ears for a clear sign of play fighting. If a cat thinks that it is about to get into a real fight, it will flatten its ears to protect them from claws and teeth. If your cats are keeping their ears out while fighting, they don’t feel as if they are in danger. Puffed up fur, easily seen on the tail, is also a sign that your cat is taking a fight seriously. Raising up fur is a cat’s natural instinct to prepare for a fight by making themselves look larger and more threatening for a fight.

A little bit of growling while your cats play fight is uncommon but could mean little if its relatively soft. If one of your cats is yowling or hissing loudly however, this is a clear sign that they are feeling threatened and are taking the fight seriously. If your cats are taking short breaks between fights and taking turns in chasing each other, this is another sign the fight isn’t real and the need for play is being reciprocated by both cats.  

Should I separate my indoor cats when they fight?

If its clear that your cats are just play fighting and the play is being reciprocated by both cats, there shouldn’t be any need to separate them normally. If your indoor cats are kittens this is especially important as this is the time in their life when they learn to play with other cats properly by limiting the strength of their bites and swats.

However, if one cat is becoming tired of play or the play is becoming too violent you should step in to separate the two before either cat becomes injured. You should do this earlier than later if aggression between your cats is a regular problem. You may also want to stop a fight if your indoor cats have become too aggressive to each other and are starting to damage furniture or put other housemates into danger.

If you think that your cat has become wounded with a bite that has punctured the skin, you should definitely stop the fight as soon as possible and take the effected cat to the vet. Wounds like this will naturally close very quickly but can lead to infections if not properly treated as soon as possible.

What should I do if my indoor cats are fighting?

You don’t want to get directly in between your two indoor cats if they are fighting or even play fighting. Its quite likely that you will get scratched in the crossfire making separation more complex. Instead, try to distract them with a toy or break line of sight with a solid object like a cardboard panel or pillow. If one cat is becoming the aggressor, it gives them an outlet for them to expend their energy on while your other cat can retreat. Using a toy to distract your indoor cats is more effective if you start before a fight escalates too far but either method will work in most situations.

If your cats have become too focused on the fight to be separated with this method, you can try scaring both cats with a bigger threat. This could be done by clapping loudly or using a spray bottle of water. We don’t normally like resorting to these types of measures with cats. We think it can be cruel and it damages the trust between cat and owner. Cats don’t understand negative reinforcement so we really wouldn’t recommend doing this every time a fight breaks out. However, in this case we aren’t trying to use negative reinforcement to teach the cats that their behavior is wrong but instead scare them to stop harming each other.

After your cats have stopped fighting you should physically separate them so they can cool off. Although its natural for us to become frustrated with the aggressor cat, nothing will improve if you punish them and may even make the aggression worse. Make sure that both cats still have access to a bed, water, stimulation, and food during this time. You can try keeping them separated for a couple of hours and continue to increase this time if they show aggression towards each other immediately after being released. If they continue to fight, your next step should be to find out what is causing the aggressive behavior.  

Why is one of my cats suddenly attacking the other?

A very common cause of aggressive fighting in indoor cats is improper introductions. Indoor cats living together need to be introduced to each other in a controlled manner otherwise they may feel threatened. If you have a cat that has been living in the house for longer, they may feel as if their territory is being claimed by the newer cat resulting in their aggressive behavior. Older cats have less energy and may become fed up with a younger cat’s constant attempts to play. If this is the case, responsible cat owners should seek to satisfy the younger cat’s need to play themselves with cat toys.

If one or both cats have both recently returned from the vet or a visit outside your other cat may be confused by the scents that the cat has picked up on their travels. They could feel as if a new animal has entered their territory, again making them more aggressive as they feel like they need to fight a new animal to protect their home. In this case you may need to quickly reintroduce your cats to one another by separating them for a short while and mixing scents together. You can also consider using synthetic cat pheromone sprays like Feliway to calm your cats. Feliway is a man-made copy of the pheromones that mother cats release to calm kittens and works on cats of all ages. It can be used in some cats to make them more comfortable.

If you noticed that your cats were watching out of the window just before they suddenly start fighting, your cats may be experiencing a form of redirected aggression. This is a phenomenon where a cat gets too much energy from a stimulus like a bird or new animal walking by. Your cats don’t have anywhere to use this energy and they end up lashing out at something they reach, like another indoor cat. Its normally easy to stop these types of fights before they break out by introducing a toy for your cats to direct their energy at. Outdoor cats and animals approaching the door are common causes of this type of behavior, you can try to stop animals coming close to your house with alarms and deterrents.  

Each situation is unique and you may need to do your own detective work over why your cats are suddenly aggressive. Changes in behavior are usually enough reason for you to contact your vet. It could be that a cat is in pain from an unseen injury or illness that is causing them to lash out at other animals through redirected aggression. If your cat continues to be unusually aggressive, you should book a vet appointment for them as soon as possible. Cats are good at hiding when they are in pain so a visit is always better sooner than later.

My indoor cats are fighting at night

As a side note, its quite common for indoor cat owners to complain about their cats fighting at night. This can be annoying as the sound of indoor cats fighting can keep a whole household awake and annoy neighbors. Cats are naturally crepuscular, meaning that they are most active in the evening and morning. This is the time they would naturally be hunting and exploring their world. It works for them when living in the wild but its not convenient for domesticated cats and their humans.

You can stop your indoor cats fighting at night by keeping them more entertained during the day. As a general guide you should try actively playing with your indoor cats for at least 30 minutes in two 15 minute sessions throughout the day. This stops them getting bored and will keep them more tired during the night. You can tire them out even more by playing for an extended period just before going to bed. If your cats still have energy after this, you can try brining out a quiet passive play toy such as a ball run just for night-time. This should may be interesting enough to distract your indoor cats from fighting each other.