How to help cats get along

Problem behaviors in cats — like aggression and fighting — can come on suddenly or gradually. When they happen, it can be stressful for you and your cat.

Any sudden change in your cat’s behavior could be a sign of an underlying medical condition. Diseases such as hyperthyroidism, osteoarthritis, dental disease, and central nervous system problems may cause aggression. See a veterinarian to make sure your cat is healthy.

If your veterinarian rules out medical problems, you’ll need to identify the cause of the aggression to develop a behavior modification plan with your vet (or other professional)".

If there’s no medical reason for your cat acting aggressively, one of the following could be in play:

Fear aggression. Fear aggression may occur in situations that make your cat feel threatened or trapped. If your cat feels afraid, they may act in aggressive ways to defend themselves.

Maternal aggression. Maternal aggression may happen when an animal or person approaches a mother cat and her kittens. The mother cat may growl or hiss, swat at, chase, or even try to bite another cat who gets too close, even if they typically get along. Maternal aggression usually goes away after the kittens are weaned from nursing. If a female cat is maternally aggressive, consider spay ing to prevent any more litters.

Play aggression. All feline play consists of mock aggression, so rough play is nothing out of the ordinary. Cats may stalk, chase, swipe, sneak, pounce, kick, ambush, and even scratch or bite each other during play. However, play can lead to overstimulation, which can escalate to aggression. This commonly happens between cats with a significant age difference.

Territorial aggression. All animals can be territorial, and cats are no exception. When cats perceive their territory is being encroached upon, they may hiss, swat, growl, and even stalk and/or chase the “intruder” — whether that’s another cat or a person. 

Your cat's eyes, ears, body, and tail all attempt to communicate their feelings — with you and with other cats and animals. Some postures and cues to look for include:

• If your cat’s ears are backward, sideways, or lying flat ("airplane ears"), they’re likely annoyed, angry, or frightened.
• If their pupils are dilated, they may be feeling nervous or submissive, or defensively aggressive.
• If their tail is held low or tucked between their legs, they may be feeling anxious. If it’s thrashing back and forth, they’re likely agitated.
• If their back is arched and their fur is standing on end, they might be scared or angry.

Cats’ vocalizations also communicate their feelings:

• Growling and/or hissing indicates your cat is annoyed, angry, frightened, or aggressive. 
• Yowling or howling means your cat is in some kind of distress. They could be in pain, trapped, or afraid.

Treatment for aggression or fighting between cats varies depending on the type of aggressive behavior but may include desensitization, counterconditioning techniques, or drug therapy.

Management methods for cat aggression include:

• Spay or neuter your cats. Fighting is common between intact (unneutered) males, and intact females are likely to have litters, leading to maternal aggression.
• Provide additional perches and hiding spots, such as boxes and cat trees. This allows your cat(s) to escape and/or hide when they feel threatened or afraid.
• Have plenty of cats’ supplies. Having multiple food and water bowls, litter boxes, perches, and toys can prevent fighting over resources.
• Reinforce incompatible behaviors — any behaviors that cannot occur at the same time as the problem behavior. Praise them and toss healthy cat treats to reward your cats.
• Try using pheromones. There are products that mimic a natural cat odor, which may be effective in decreasing aggression.
• Keep cats separated, especially at mealtimes. Separation may need to last only a few days, but if the aggression is persistent and severe, it may take several weeks before you can gradually reintroduce the cats. 

When you’re trying to help your cats get along, it’s important to pay attention to whether they’re playing or really fighting. If the fight is real, you want to break it up and respond appropriately afterward.

• Don’t let them fight it out. If it’s a real fight, never let your cats fight it out. Cats don’t solve disagreements with aggressiveness. You don’t want to get in the middle of two fighting cats, so try to distract them instead, with a loud noise or sudden movement to break their concentration on their fight.
• Don’t punish your cat. Never punish your cat for aggressive behavior toward another cat. Punishment can make fearful or aggressive behaviors worse.
• Don’t reassure them. In that same vein, don’t try to calm or soothe your aggressive cat. Instead, give them space.

If your cat’s aggression is severe or becomes unmanageable, contact a Certified Applied Animal Behaviorist (CAAB or ACAAB) or a board-certified veterinary behaviorist (Dip ACVB) for guidance. These professionals can provide deeper insight and guidance on behavioral modification for your cats. 

Unfortunately, some cats simply cannot live together peacefully. If you’ve exhausted your resources, time, and energy in the hopes of resolving aggression or fighting between your cats, it may be time to consider finding a new home for one of them or keeping them permanently separated.