Dealing With Aggressive Behavior In Your Cat

Dealing With Aggressive Behavior In Your Cat

Why Does My Cat Bite & Scratch And What Can I Do About It?

Ron Hines DVM PhD

Destructive Behavior?  

 Litter Box Accidents?  

 Sweetheart Cats

Some house cats, like some people, are sweethearts. They crave human affection, companionship, touch and attention. They are trusting, tolerant and mellow. They come to us with their tails straight up to greet us at the door. They rarely show displeasure and when they do, their inclination is just to leave. They don’t hold grudges. But there are a few – perhaps 10-15% these days – that remain aloof, timid and even aggressive toward their owners. Most arrived by way of an animal shelter. Sometimes the staff was honest about the cat’s personality, sometimes they weren’t and sometimes they did not know. This article is about those cats, why they are that way, your options in living with them and why the problem is considerably more common today than it once was.

Aggression And Your Cat’s Genetics

Genetics almost certainly plays a part in your cat’s friendliness. Genetics does in every species of animal – us included. There were two studies that appear to show how important your cat’s genes were in determining its friendliness. But both were poorly designed for their results to be applicable the general cat population. You can read them here  & here .  Another study on why some kittens cry more than others mentions that genetic variations were one thing that needed to be considered. (read here) Another found a link between aggressiveness and hair coat color, tortoiseshells and female orange, calicos, “torbies”,  gray-and-white cats, and perhaps black-and-white cats were owner-reported to be more aggressive toward them. There is a paywall keeping you from reading it, but if you ask me for Stelow2016.pdf I’ll lend you my copy. 

Genes responsible for agreeableness always accompany the domestication of animals for or companionship or food. In the loose tom cat, feral, or homeless cat populations, there is no advantage in having them. The dominant Tom in your neighborhood remains king of the mountain because of his aggressiveness. (read here) No single cat gene is responsible for aggression, but studies across the spectrum of animals tend to focus on the monamine oxidase A (MAOA) gene that controls your cat’s monamine oxidase A level. Monamine oxidase has important effects on docility and aggressiveness in domesticated animals (the many studies that confirm that were done in livestock and humans, not cats). None of these genes work independently of your cat’s early life experiences. They are just an open door to the problem. One survey of 1,717 cats, found that 16.7% had various states of anxiety and aberrant (abnormal) behavior of which 10.5% were forms of aggression. That is opposed to about 1-3% of the human population that have been found with aggressive tendencies. A perceptive observer can already see tendencies toward aggression in kittens; children begin to exhibit those tendencies at about 17 month of age. (read here)

Aggression And Homeless Cats

Cat aggression and socialization failures are much more common today than they once were. That is because in the past the spaying of female cats was uncommon. The chief source of a new kitten was your neighbor’s in-and-out cat that had an unplanned litter in or under the house. In rural areas it was the farmer’s barn mouser that gave birth. Kittens from those sources tended to be well adjusted. The humane movement did not exist, animal shelters did not exist, group homes did not exist, so cats that did not fit the desired personality profile were simply pitched.  

Urban homeless and semi-homeless cats live unnatural stress-laden lives as do the kittens they give birth to. House cats are derived from native wild cats whose mothers and offspring lived widely separated from one another to assure them an adequate food supply. Whatever abilities cats have acquired to live in crowded unrelated groups they have only acquired since intensive grain farming began in the Middle East (~10,000 years ago). Because they did not develop from pack animals cats (unlike dogs)  lack the ability to make or interpret complex visual signals that allow non-violent peck order assignment to form. Cats are intensely territorial. You may not be aware of it but invasion of their space by strange or unaccepted felines causes them immense stress. Cat colonies confront cats with situations Nature did not biologically equipped them to deal with. (read herehere)  Activists of all stripes lead with their emotions and rarely if ever understand the long-term consequences of their actions. There are many cat activists who do not accept or acknowledge any of these points. (read here) They consider it  politically incorrect to mention these points. They will also be quick to blame you when problems integrating their new cat into your household arise. One cat may look like another. But homeless cats different from from well-socialized house cat in subtle psychological ways. (read here

I was a foster parent in the Texas state welfare system for many years. The social workers we dealt with had the same tendency to minimize the psychological problems of the children we cared for.  We were instructed to minimize these children’s psychological issues when potential adoptive parents came to call. Texas found it much cheaper to adopt these children out than to pay for their long-term care and psychologist bills. In the end, that often proved a disservice to the children and their adoptive families.

Aggression Resulting From A Lack Of Normal Kittenhood Socialization

I mentioned to you earlier how critically important a kitten’s early life experiences are in molding its adult personality. All kittens are born with a brain that is quite “plastic” (moldable) as to how it perceive and adapts to the world around it. What a kitten perceives as family, what it finds enjoyable, what it perceive as a threat or a rival and how it deals with stress are all dependent on its early experiences. That window of opportunity that determines if a kitten will grow up to be a well-adjusted cat opens considerably earlier and closes considerably sooner than most people suppose. Some observers of cats believe that window opens as early as the kittens first week – even before its eyes open (at 7-10 days). The first signs of sociality in kittens is already well formed by the time they are 3 weeks old. Others consider the kitten’s first 3-8 weeks as the most critical time to develop lifelong inter-cat and inter-human tranquility. (read here)

It is important that kittens be handled and talked to before their eyes open. That critical sensory learning begins so early in kittens shouldn’t be a surprise. Human infant perception of touch begins long before birth. The tactile (touch) of humans needs to be experienced by kittens even before vision develops. Its quite possible that cats not experiencing human touch in their infancy might find your stroking and petting objectionable as adults. No one has really looked into that.

In their haste to get kittens out of feral colonies, shelters and of the owners of unexpectedly-pregnant cats to relieve themselves of the burden of kitten care, many kittens are fully weaned much too soon (earlier than 12 weeks).  That deprives them of their mother’s nurture and accumulated wisdom. Cats in the wild,  Felis silvestris , wean their kittens at 3.5 – 4.5 months. Another reason for group home haste are the virus exposures so common in cat shelters and feral colonies. Some have noted that kittens, unaccustomed to humans look to their mothers when forming positive attitudes toward people and accept human companionship better when their mother is present and feels the same. (read abstract here) or ask me for Crowell-Davis2004.pdf Others have also noticed that kittens un-handled in their infancy are handicapped in forming close human or inter-cat attachments later in life. (read here) It is also common for homeless cats to wean their kittens too early due to the stress of colony living, starvation, parasites and disease.

When friendly normally-socialized cats meet they greet each other by rubbing (allorubbing) – a very positive experience for well-socialized cats that have learned it a kitten.   One could take that to the extreme and postulate that kittens not experiencing handling during the critical early period might resent your petting and touching them later in life. Those cats might attempt to leave or respond aggressively to you when you try. (read here)

Are You Telling Me I Should Not Give Problematic Cats A Home?


I do not want to discourage you from taking in one or more of these homeless partially socialized cats or kittens. I just want you to be aware of the realities when you do so.

What Are Some Of The Things I Might Try To Minimize Aggression And Other Objectionable Behaviors In My Cat?

Much of your cat’s attention revolves around the food resources you provide and feeding time. It is a time when even poorly socialized cats are forced to interact with their housemates and owners. How often you feed your cat(s), what you feed and where you feed has a major influences on your cat’s mood and behavior. Cats are pre-programmed to eat frequent small meals throughout a 24 hr day and to do so in solitude. They are not pre-programmed to consume large infrequent meals in a community setting around a shared food dish. My preference is for multiple programmable and puzzle feeders located as far as possible from each other. ask me for Gonzalez2018.pdf

Another important activity for a cat is marking its territory. Doing so gives a cat a sense of security. Much of those territorial urges center around its litter box – its equivalent of a forest marking tree. Multiple cats in a household are never entirely comfortable sharing a litter box. It is not in their underlying nature to do so. So changes in the location, number, size and type of litter you provide can have positive and negative consequences on your cat’s mood, interactions and feelings of safety throughout the day. Every now and then, topical products are introduced that are said to mellow the mood of cats. Some that are thought to have hormonal calming activity are suggested in or near the litter box. To date, they have met with mixed or contradictory results. You are welcome to give them a try.

Environmental Enrichment For Your Cat

An indoor life without sufficient stimulation is just as boring for your cat as it would be for you. Some cat owners remedy for that is to leave the house side door ajar. I don’t suggest you do that for a great number of reasons. For one, in-and-out cats have considerably shorter lifespans.  There is a better way to avoid feline boredom. Altering your cat’s indoor environment to add stimulation and activity options will positively alter its general behavior: safe places to climb, hide and snooze, locations of solitude from you and other cats. Some of those preferred locations should be elevated (eg cat trees and shelves). The internet is full of ideas. Many are likely to reduce hostility and stress. 

What About Medications To Treat Aggression And Other Personality Issues In My Cat?

I believe that quite a few cat owners, some cat psychologists and even some veterinarians fail to recognize that in cats with behavioral issues, brain anatomy and circuitry communications have physically changed. (read here) Veterinarians like me have no medications that will reverse those changes nor do we have medications that specifically treat aggression. What we do have are drugs that “lower the volume” of response to various stimuli in general. Because of that none are ideal.

All of these medication options basically mask an underlying brain circuitry problem. They do not cure it. I particularly avoid giving these medications to cats that deliberately attack their owners. That is because I have seen too many cat owners mauled by their cats while on or off medication. Perhaps the medication was ineffective, perhaps the dose was too large or too small, perhaps the medication dosing frequency was too often or not often enough. Perhaps a dose was forgotten due to preoccupation with other matters. Perhaps the cat spit it out. Every cat is different. I feel  personal responsible when one of my clients calls and tells me that she/he was injured. There are also legal liability issues for veterinarians but they are not what concern me. I am not telling you to declaw your cat. But you can read some of the human health issues related to cat bites and claw scratches here.

Specific Medications

Faced with aggressive cats years ago, veterinarians resorted to methods similar to shock therapy. Some subjected cats to periods of deep barbiturate anesthesia. Others removed portions of their blood (anemic cats do not attack). Still others gave them injections of hormonal drugs such as ACTH, megesterol or medroxyprogesterone that jolted their hormonal systems. (read hereherehere,   here  &  here) Obviously, their mood did change – at least temporarily. Today, your veterinarian has more targeted medications to offer your cat.

General Sedatives

Benzodiazepines like Valium®  are known to reduce anxiety (anxiolytic drugs). Their expected effect is through general sedation. However occasionally unexplained excitement or major liver dysfunction occurs when these drugs are given to cats. (read here) That is probably dose and dose frequency related. Cat appear to be less susceptible to than humans to  drug tolerance  (requiring higher doses to achieve the same effect). I do not know of that having occurred with this class of drugs given to cats. 


Drugs developed to treat human depression are also in use for feline behavior modification. The most common ones veterinarians dispense to cats today to combat aggression are fluoxetine (Prozac®), buspirone (Buspar®), amitriptyline (Elavil®) and clomipramine (Anafranil®). Possible side effects of these drugs include generalized sedation and disorientation. Buspirone appears to be the most free of unwanted side effects when given to humans. In one early study, neither buspirone, Valium® or amitriptyline appeared to decrease intra-cat aggression. read here:    Since then, the only study I know of that administered any of these drugs to cats on a controlled basis only determined that transdermal (rubbed on the skin) application of buspirone and amitriptyline was ineffective. (read here)

I rarely recommend any of these medications for long term use in cats. The first reason is that I find it cruel to keep a human or an animal “drugged up” for personal convenience. The second is that medicating a cat orally – especially one that is sociologically challenged – is never easy for the cat or you. With time your cat will learn to leave when it sees you coming. There are pharmacies that will gladly mix these medications for transdermal application to your cat’s ear. Even though I just mentioned that one attempt with buspirone and amitriptyline was found to be ineffective, perhaps it is dependent on the skill, carrier ingredients and compounding methods used by individual druggists. If you elect to give any of them a try, I would give the medication a 2-months trial – if your cat accepts your applying them without a fuss. That is because you have so few alternative options when non-pharmaceutical options fail.


Trazodone is an antidepressant medication primarily sold to treat depression, anxiety and alcohol dependence in people. In humans and cats it is also a sedative. (read here) Trazodone has been given to people to control aggression. How long-term administration of this drug might affect cats has not been determined.

What About A Cat Psychoanalyst?

Discussing you and your cat’s situation with another empathetic person is always comforting. As with humans, basic cat personalities once established in kittenhood do not readily change. (read here) But that doesn’t mean that they cannot be improved through some of the techniques I mentioned earlier or that your skills in coping with these situations cannot be improved through professional help. If you elect to use one of their services, I suggest the person visit your home in person to get a good feel for you and your cat(s). Every cat-to-human relationship is unique and requires a unique approach. It is not something that can be done by checking boxes on a form, cookie cutter consultations over the internet or by phone. Diplomas and position award no access to empathy. It might turn out that your best psychoanalyst is the doorman at your condo. Cat owners faced with decisions on the fate of an unmanageable cat experience enormous guilt. At the least, giving these people a try lets you assure yourself that you have left no stone unturned.

Do You Have Any Advice When I Choose Another Cat?


You came to this article because you already have a cat with “interpersonal” issues. It probably won’t be the last cat you have and if you are  a cat person, you have friends you can pass this advice on to. I have worked with cat shelters and newly adopted cats for many many years. Here are some things I have learned: When you choose to have more than one cat. Your chances for successful peer cat and owner acceptance and a tranquil loving relationship for all are always better if the two or three cats are littermates. If not genetic sisters, then kittens that grew up and nursed on the same mother simultaneously. If not that, cats from the same colony source.

I mentioned earlier that kittens and cats born in a low stress environment are much less likely to have psychological (and general health) issues. I am talking about random-bred, run-of-the-mill house cats from your neighborhood feline gene pool. Once you opt for a cat or kitten from a breeder, inbreeding and genetics come into play across the entire spectrum of physical and psychological health.

When you are observing cats in a shelter environment or homeless cats in the field, observe them from a distance. When you see two or three mature cats that consistently stay close to each other, perhaps lying together in physical contact one using the other as a pillow or licking each other (allogrooming). Those cats are almost certain to make good housemates. 

I mentioned earlier that the mission of animal shelters is to place as many of their wards in homes as possible. Several I worked with had a no-return policy. If you have the mind for it, find a shelter that will let you foster two or three kittens or cats for two or three months under the understanding that you will return them, no questions asked and no guilt, if their relationships and behavior in your home is not what you seek. Over the years I have observed that once you have given them names, you will find it exceedingly difficult to give them up.

Choose your cats as you choose your friends, based on their personalities and not on their visual appeal. Many divide general feline personalities into three types. But the divisions in temperament between the three are not as crisp as I and others list them below. Once established in a cat, those personality types rarely if ever change.

My favorite cat is the sociable, confident and easygoing cat. It will come up to you in curiosity even if you are a total stranger. When it does, it will carry its tail straight up with a slight curl at the tip. After circling you, it will rub on your leg and purr. If you extend your hand, it will sniff it. It will often roll over at your feet. It will chase a toy or a string (bring one in your pocket). It passes by you again and again to be stroked. As it does, it makes trill and chirping sounds. If you pull gently on its tail, it will simply turn around. If it is in an animal shelter cage, it is lounging near the front. It might yawn in your presence. These cats make excellent companions. They have loving relationships with their owners and usually get on well with their feline housemates as well.

The second type of cat is shy, suspicious and fearful. It will withdraw from you if you approach it. It resents handling. When forced into situations that are too intimate, it is likely to claw or bite. It will also take a swipe at you if you gently pull on its tail.  If it is in an animal shelter cage, it is in a rear corner. It is too tense to yawn in your presence. These cats were never properly socialized as kittens.  When adopted, they are over-represented in cats with inter-cat and inter-owner issues.

The third type of cat is excitable, nervous and tense. It ignores or is hostile other cats. It regards you with an intense stare. It stands its ground when approached and will spit, hiss or growl. Its only motivation to approach its caretaker is to be fed. These are the cats most likely to attack their owners and housemates.

Are Cats That Don’t Pass Those Personality Tests All Fated To Become Problem Cats?


Animal shelters are places of turmoil for cats. Even a very social cat is likely to be fearful in such an environment. The caretakers of those cats are in a conundrum. If they wait long enough to truly judge the temperament of the cats and kittens that come through, they cannot keep up with the inflow of new cats. If they maintain high numbers of cats under evaluation, they exhaust their financial resources. If they maintain incoming cats and cats being evaluated in the same facilities, they experience periodic outbreaks of disease. If they keep cats long enough for the cats to revert to their true dispositions, other health issues can be discovered that require expensive veterinary care. As the veterinary industry consolidates, the accumulation of money increasingly dictates corporate decisions.

Not only the cats are stressed by the realities of the times; it is highly stressful to the people providing their care. Over the years, I have seen the emotional exhaustion, turnover and negative effects on the general health of the angels who attempt to assist these animals. Many of my friends in that calling passed away much too soon. I suppose that it is not that different in other high-stress, emotion-laden jobs that take a toll on your empathy. Is it any wonder that they are motivated to places as many cats in homes as they can, as fast as they can, with little time to contemplate if the new home is a good fit? The truly compassionate people who volunteer at your local animal shelter are not the greedy ones with the slick commercials you see panhandling on the internet and television. Give them a dollar and if you are lucky perhaps 20 cents will trickle down to the cats.

What About Cats That Develop Aggressive Behavior Or Other Objectionable Behaviors Later In Life?

Cats that were once human and inter-cat social but loose those attributes suddenly or over time have a different set of issues. Of course they may have mild pre-existing socialization issues as well. When this occurs in a household of cats, it is often due to the introduction of a non-compatible cat. Less frequently but also common,the problem is due to major changes in the household that do not involve a new cat. It can also be due to things you might not have considered. Things like the cat viewing another cat through a window. When you are certain that no such event occurred, personality changes are often due to health issues that the cat is facing. Let your veterinarian sort that out.

When it is your older cat that no longer appreciated being petted or picked up, it can be due to arthritic pain. You can read about ways to manage that pain here.   As I mentioned, it can also be due to the many other health issues that older cats face.  Hyperthyroidism, so common in older cats, commonly causes hyper-excitability and personality changes. Read about hyperthyroidism in cats here. Although the mental decline of old age (cognitive dysfunction / pet Alzheimer’s) is said to occasionally cause aggression. But issues such as loss of litter box training and confusion are much more common symptoms of the mental decline of old age. 

If you let your cat outside unattended, the number of health issues to consider is considerably greater.

Poorly socialized female cats with kittens can be quite aggressive in protecting their kittens if they are disturbed.

How Should I Introduce My New Cat Into My Feline Family?

If your future cat will come from an animal shelter, spend some time looking over their available cats using some of the methods I mentioned earlier to judge their underlying dispositions. Bring your parents or a friend if you like but I prefer you not bring your children prior to their having developed  delayed gratification . Sign an agreement with the staff to adopt the cat that you choose. I prefer those that do not insist that you spay or neuter kittens as infants. Doing so brings up a whole different set of health issues which you can read about  here

Be sure the cat is already free of fleas, ticks, internal parasites, ringworm and ear mites. Check its litter box to be sure its stools are well formed. I prefer that the cat’s health has already been recently checked by their participating veterinarian. I would not adopt a cat whose  feline leukemia  and  feline AIDS/FIV  status had not been recently checked unless you have other positive cats at home or are willing to deal with the chronic health issues those virus produce. There is nothing as disconcerting to a veterinarian like me as to have to convey bad news to excited happy clients who drop by with a newly adopted cat – be that anti-social or physical health issues I have found.  Have a person in authority at the shelter agree that you can return the cat to them, no questions asked, if things do not work out. 

Earlier in the day, go to the store and buy a spacious, high quality pet carrier. Not the cardboard one the shelter will probably give you. Use it to pick up your new cat. Have the staff bring the cat to you and place it in the carrier. Do not let them take the carrier to the back where it can pick up the odors of other cats. Do it on a non-hectic morning for you and for their staff – after their feeding and cleaning chores are over. No cat should ever leave its current residence/location without an identification tag and collar. Microchipping is fine, but it is no substitute for a readable identity tag. 

If you already have other cats at home, those that previously accepted newcomer cats are more likely to accept them again. The reverse is also true. Hopefully you have a room entirely separated (but not too distant) from the cats you already have. Preferably a room that is not already a preferred location for one of your resident cats. It should be a quiet room in which you can place separate food, water, litter boxes, enrichment activities and a hiding area. A cardboard box will do.  Some find that the liberal use of Feliway™-type products in the new and resident cat’s quarters during this adjustment period is helpful. Having a house call professional clip all of your cat’s toenails is always prudent when stressful situations are anticipated.

I would maintain that situation for about a week – perhaps more if the resident cat(s) or the newcomer appears tense or agitated. Perhaps a few days less if everyone remains mellow. After the first day or two, depending on how calm things appear, take a small piece of your recently worn apparel or one of your used small towels. Stroke the new cat down with it. Then place the item in a corner of the living areas of the resident cat(s). If all goes well, repeat that from day to day until the resident cat(s) show no interest in sniffing the cloth. I worry more about cats not getting along that show no interest in sniffing the scents on the cloth than those that do.

Gradually increase the contact between the cats. Perhaps there is enough space under the door to the new cat’s room for your resident cat(s) to explore the new arrival. If not, devise some way for the cats to see each other and observe what happens. Which one’s tail goes up, which goes flat, whose ears lay back, which if either tenses up, spits or hisses. Rubbing the divider or purring is a very positive sign for either cat. The one that doesn’t is likely to have the most problematic with the new relationship. When you do attempt to allow the cats free access to one another be sure to have extra food stations, litter boxes, water dishes and hiding areas. The more the better. You will need to chaperone them for a while until you are certain that they have become compatible. Play with both cats for short periods.

If altercations occur, go back to the previous living situation, give them more time, and then try again. Keep towels and heavy gloves handy to separate cats if necessary. Once the cats appear to tolerate each others close presence, let them develop their relationship at their own pace. Don’t attempt to push them closer to each other or to compete for resources, snacks and toys in an attempt to break the ice. That may work with your small children, but it does not work with cats and it tends to be counter productive.

How Can I Tell If My New Cat Or The One I Already Had Is Uncomfortable Sharing A Home?

Cats that are uncomfortable with each other rarely interact. When they do, it is often aggressively over the possession of choice resources (food, toys, favorite resting area, etc.) One cat will often leave the room when the other cat arrives. They tend to watch each other intently giving none of the indications of inter-cat affection I mentioned earlier. They are tense when circumstances require that they be in close contact. They never sleep near each other nor do they groom each other. One or both may loose their toilet training. An occasional blink is a sign of a relaxed, contented cat. One rarely sees that in a cat uncomfortable in its living arrangements.

You are on the Vetspace animal health website

Visiting the products that you see displayed on this website help pay the cost of keeping these articles on the Internet.