If you have more than one cat living under your roof, you may be familiar with catfights. But how do you know if it's play aggression between cats, when to worry, and what to do about the fighting? When cats are fighting frequently, it can be frustrating for pet owners and potentially dangerous to cats, sometimes even drawing blood. It's not a good idea to allow cats to "fight it out" because this rarely settles conflicts and usually makes matters worse. Learn the types of behaviors and how to stop aggression between cats so your household can stay at peace.

Why Do Cats Fight?

Cats usually display social standing with posturing and "bluffing" communication that typically do not result in injuries. If they get along, they can usually learn to tolerate or avoid each other as well. However, this likely won't always be the case and fights may break out for any number of reasons:

• Fighting between same-sex cats that have not been neutered or spayed may worsen during mating season.
• Bullying the lowest-ranking cat—often an older or infirm kitty—can become rampant as the victim cat starts slinking around, using submissive ​body language, hiding, and inviting even more bullying.
• Moving or rearranging a cat's environment, including cat furniture, feeding stations, or litterboxes can cause fights.
• Any change in routine may leave cats so stressed that they take it out on each other.

Cats use vocal and silent communication to elevate their status in the eyes of the other felines. They challenge each other with stares, forward-facing body position, hisses, growls, mounting behavior, nape bites, or blocking access to food, play, or attention. Some dominant cats use "power grooming" behavior and aggressively lick another cat to make it move away.

Aggression Types

Not all expressions of aggression are the same when it comes to cats. There are many types of aggression in the feline world, and it can help you achieve more patience if you understand the possible reasons behind the attacks. Here are the types of aggression that cats can experience:

• Fear aggression: A scared cat facing unfamiliar circumstances or unknown cats may transmute its fear into aggression as a way to try to control the situation.
• Inter-cat aggression: Usually male cats will become aggressive with each other between two and four years of age as they reach social maturity unless they are neutered. Female cats rarely engage in this behavior, but it can happen to cats that are not spayed. Most instances of inter-cat aggression can be decreased or prevented by spaying or neutering cats before their first birthday.
• Maternal aggression: New mother cats will show aggression towards any human or cat encroaching on her newborn kittens, but the aggression should subside as the kittens mature.
• Pain-induced aggression: If a cat is in pain, it may become aggressive with humans and cats. It will be tough to tell if this is the case with catfighting, but if your cat also recoils from your touch, there could be an illness and may warrant a call to the vet.
• Petting-induced aggression: A cat that is overstimulated by petting or by another cat's playful antics may become aggressive. An aggressive cat is trying to tell the offending party to stop.
• Play aggression: Unsocialized cats, or cats that did not grow up with littermates, may be too aggressive during playtime with other cats. Cats typically chase and roll around with each other, but socialized cats will do so with ears pointed forward and they will let the playmate know if it's gone too far resulting in the play stopping without any intervention. You can usually tell if a cat is going to engage in play aggression because it may be stalking another cat. Distraction and redirection are the best antidotes for this type of aggression if it gets out of hand.
• Redirected aggression: A normally calm cat may turn aggressive towards a housemate cat if it is stimulated by an unrelated situation such as seeing a stray cat outside the window or hearing an unbearably loud noise nearby.
• Status-induced aggression: A cat may try to be the alpha cat at any time, and may take aggressions out on cats and humans by swatting and blocking doors.
• Territorial aggression: This type of aggression is complicated and notoriously hard to correct. Cats use scent to imprint property and do it with cheek rubs, patrolling, and marking behavior. When introducing a new cat into your home, or welcoming back a cat that was away for a hospital stay, for example, other cats will try to defend their territory from the intruder. A lack of space can also incite feline territorial disputes. Reintroductions between cats may be necessary.
  

How to Stop Aggression

If your home is the site of frequent catfights, it's important that you do your best to stop it; not only for your cats' health but also for your own well-being. This is not an overnight process—behavioral conditioning can take months. Stick with it, but also realize that some cats may never get along. Here are steps to take to curb the catfighting:

1. Add more territorial space to prevent cats from having to share climbing, hiding, and perching areas where fights can break out.
2. Increase the number of toys, cat trees, litter boxes, and feeding stations to reduce competition for resources. Create at least one feeding station and one litter box location per cat. If you have the resources, adding an extra set is even better. 
3. Consider giving the bullied cat use of an electronic cat door opened by a magnetic "key" inside a collar. This device gives the passive cat access to the entire home while having a safe area to go to where an aggressor can't follow.
4. Try pheromones to reduce tensions and modify behavior. Pet stores sell products that mimic natural cat odor (humans can't smell it) and that can significantly reduce stress. Diffusers may be more effective than sprays.
5. Speak with a board-certified veterinary behaviorist to see what kind of professional therapy may be helpful. Certain medications may control the aggressive behavior in the bully cat while decreasing the defensive posturing and vocalizing of the threatened cat. While it's not a cure, medication may be a tool that enables further training to work more effectively. 

When all tactics have failed to stop two indoor cats from fighting, one cat may need to be placed in a new home or permanently segregated from the other. Don't consider it giving up; it's making life better for your cats and ensuring that they are happy no matter where they live.

How to Break Up a Catfight

If you're witnessing a catfight breaking out, there are steps to take to deescalate the brawl. Resist the temptation to break it up physically yourself. You'll only end up bloody and scratched and potentially lose the trust of one (or both) of your cats. Take these steps to break them up:

1. Use distraction to stop the squabble: Loud noises can do the trick, but only if you're out of sight so you're not seen as a third aggressor in the fight. Try clapping your hands, banging on a pot, or throwing a large, soft object like a pillow near the cats to stop them in mid-swat.
2. Redirect the bully cat's behavior: Try to catch the aggressive cat before it gets hissy with the passive cat by redirecting its behavior with an interactive toy such as a flashlight beam to lure it into play instead of war. Once the aggressive cat walks away and is calm, then you can reinforce its good behavior with a desirable treat, toy, or attention.
3. Avoid rewarding poor behavior: Giving food to the aggressive cat while it's already in the throes of fighting may calm the angst in the short term, but it rewards the bully.
   

How to Get Cats Used to Each Other

You can help your cats tolerate each other with another tactic that gets back to the basics. Treat the fighting cats as though they are being introduced for the very first time. Give the passive cat the choice of locations within the house, sequester the bully cat, and then make a controlled introduction. Expose the cats to each other with cat carriers or a harness and leash used in a hallway or large room. During these meetings, feed cats tasty foods or engage in play so they learn to associate each other with fun, positive rewards.