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?

Some house cats are sweethearts. They crave human affection, companionship 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. But there are a few – perhaps 10-15% these days – that remain aloof, timid and even aggressive toward their owners. This article is about them, why they are that way, your options in living with them and why the problem is considerably more common today than it once was.

Your Cat’s Genetics

Genetics almost certainly plays some role in your cat’s friendliness. It does across all species lines. Two studies appear to show genetics is important in cat friendliness – but they poorly designed for their results to be applicable to our general cat population. (ref1, ref2)  Another study on why some kittens cry more than others mentions that genetic variations were one thing to consider. (ref) There is also one study that relates aggressiveness to coat color for which I can provide no explanation. (ref)

Genes for agreeableness always accompany the domestication of animals for food or companions. In the loose tom cat, feral, and 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. (ref)

Genetics was most certainly at play when I worked with the early Asian leopard cat/house cat crosses that eventually became the Bengal breed. (ref) I could only handle them with gauntlets. But controlled studies on how genetic influences a cat’s personality  are rarely if ever performed – I know of none, other that the three I listed.
The genetic variation of random-bred cats was found to be about was 86%, compared to 93-95% in us humans. (ref) A  1997 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. (ref)
That is opposed to about 1-3% of the human population that have been found with borderline personality abnormalities. (ref)

So I will venture a guess that if you have an ordinary, non-purebred cat with aggressive personality problems, it has nothing to do with its genes and even less to do with its home environment.   It has to do with its early life experiences. Now there are groups that resist this interpretation; primarily those that attempt to find homes for feral cats and their “rehabilitated” offspring. (ref)

Homeless Cats

Cat socialization failures are considerably more common today in cats than they once were. That is because in the past, the spaying of female cats was uncommon. The chief source of kittens in those days was a neighbor’s cat that had her unplanned litter in or under the house. In rural areas, it was a farmer’s barn cat mouser that gave birth. Kittens from those sorts of sources tended to be well adjusted. (rptref)

Urban homeless cats live in an unnatural stress-laden environment, as do the kittens they give birth to. They are derived from native wild cats in which mother and offspring lived widely separated from one another. Whatever abilities they have acquired to live in 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 lack the ability to make complex visual signals that allow non-violent peck order assignment. Cats are intensely territorial – 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 for. (ref1, ref2)   Activists of all kinds lead with their emotions and there are many cat activists who do not accept or acknowledge these point. (ref)

One cat may look like another cat. But homeless cats different from from well-socialized house cat in subtle psychological ways. Some are more apparent than others (ref)

Deprivation Of A Normal Kittenhood Socialization

I mentioned earlier how critically important a kitten’s early life experiences are in molding its adult personality and that that importance of that is often minimized by cat shelters and cat-rescue groups. I do not fault them a bit for that.  Their mission is to find homes for homeless cats – not put up obstacles to their placement. It is a tendency not limited to cat groups. I do fault them, however, when they shift the blame for adoptions gone wrong to the persons who took in the cats. (ref)
I was a foster parent in the Texas state welfare system for many years  and social workers here had the same tendency to minimize the psychological problems of the children I cared for in a desperate attempt to find them permanent homes. In the end, that often proved a disservice to the child and their adoptive family.
A kittens are born with a brain that is quite plastic as to how it perceive the world around it – what it perceives as “family” what it finds enjoyable, what it perceive as a threat or a rival, how it deals with stress. However, 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 many 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 present when they are 3 weeks old. (ref) Others consider the kittens first 3-8 weeks as its most critical time to develop lifelong inter-cat and inter-human tranquility. (ref)

In their haste to get kittens out of feral colonies or of the owners of unexpectedly-pregnant cats to relieve themselves of the burden of kitten care, many wean and dispose of  the kittens at less than 12 weeks of age depriving them of their mothers nurture and accumulated wisdom. Some have noted that kittens, unaccustomed to humans look to their mothers when forming positive attitudes toward them and accept human companionship better when their mother is present and feels the same. (ref)

More importantly as to the success of future placement, the kittens were not handled sufficiently by humans to be able to form close human or inter-cat attachments later in life. (ref) It is also not unusual for feral mother cats to also wean their kittens too early due to the stress of colony living, parasites and disease. That critical sensory learning begins so early in kittens should not be a surprise to anyone. In human infants, it begins even before the date of natural birth. (ref1, ref2, ref3) Tactile (touch) senses are sufficient for a kitten, 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.

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

I believe that all these disabilities likely contributed to a recent 251 cat-owner survey that found that former stray/feral cats and their offspring tend to be more human non-social and more human-aggressive than cats obtained in the former traditional ways. (ref) One of the top reasons adult cats end up in shelters or homeless is that their personalities did not match the expectations of their new owners. Rather than making the “sell” I believe that shelter staff need to concentrate more on confirming the “fit”. (ref) Not doing so adequately is a disservice to both the cat and its new owner (aka guardian/trustee/conservator/etc/etc).

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 of doing so. When my children were old enough, I accepted foster children. I learned early on in the Texas child foster care system that traumatized kids were never going to say “thank you for taking me in” but I wanted to offer them a home just the same. Different motivations prompt people to adopt cats. Perhaps a more distant companion is what you desire. There are also, many people who derive great personal satisfaction in life from the altruistic deeds they do. But you might want to consult with the cats you already have and your two-footed partners before you elect to do so.

I have a somewhat unique perspective on feline-human aggression. That is because I deal allot with cats in which aggression is perfectly normal. In fact, I would worry about their psychological and physical health if they did not exhibit it toward me. At many points in my career I dealt with wild felines. These days, I receive injured and orphaned bobcats from Texas Parks & Wildlife to raise, rehabilitate and re-release.

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

Much of a cat’s attention revolves around the food resources you provide and feeding time. It is a time that even poorly socialized cats are forced to interact with their housemates and their owners. How often you feed, what you feed and where you feed can have major influences on your cat’s mood. Cats are pre-programmed to eat frequent small meals throughout a 24 hr day in solitude. Not large infrequent meals in community around a food dish. Multiple programmable and puzzle feeders. (ref

Another important occupation of a cat is marking its territory. Doing so gives them a sense of security. Much of those territorial urges center around its litter box. Multiple cats in a household are never entirely comfortable sharing a litter box. It is not in their nature to do so.  So changes in the location, number, size and type of litter you provide can have consequences on a cat’s mood and 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. (ref)

A Richer Environment

Altering your cat’s general environment to add stimulation and activity options will also 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).  All tend to reduce hostility and stress. You can read in detail about techniques that appear to lower stress levels in cats here, here, here and here.    

What About Medications To Treat Aggression And Other Personality Defects 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 communication have physically changed. (ref) In 2018, we have no medications that can reverse those changes nor do we have medications that specifically treat aggression. What veterinarians do have are drugs that “lower the volume” of response to various stimuli in general. None are ideal.

All of these medication options basically mask an underlying 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. Perhaps the medication was ineffective, the dose too large or too small, the dosing frequency to often or not often enough. Every cat is different. Perhaps a dose was forgotten due to preoccupation with other matters. Perhaps the cat spit it out. Whatever the cause, I feel a personal responsibility 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. You can read some of the human health issues related to cat bites and claw scratches here.

I now realize I failed to specifically mention trazodone in this article. Trazodone is another antidepressant veterinarians sometimes resort to when dealing with frustrating behavioral issues in cats. Read some articles on the medication’s use in cats here  and  here  . 

Faced with aggressive cats in the 1970s, veterinarians resorted to methods similar to shock therapy. Some subjected them to periods of total barbiturate anesthesia. Others removed portions of their blood, Still others gave them injections of drugs like ACTH, megesterol or  medroxyprogesterone that jolted their hormonal systems. (ref) Obviously, their mood did change – at least temporarily. Today, your veterinarian might offer you other medications for your cat.

Benzodiazepines like Valium are known to reduce anxiety (anxiolytic). Their general effect is sedation, occasionally excitement and occasionally major liver dysfunction. (ref)

Drugs developed to treat human depression are also in use for feline behavior modification today. The most commonly dispensed to cats today are fluoxetine (Prozac), buspirone(Buspar) amitriptyline and clomipramine. Side effects of some of these drugs include generalized sedation and disorientation. Buspirone appears to be the most free of unwanted side effects when given to humans. However in one study, neither buspirone, Valium® or amitriptyline appeared to decrease intra-cat aggression. (ref)

I rarely recommend giving 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. With time cats learn to leave when they see you coming. There are pharmacies that will mix these medications for transdermal application to the cat’s ear. That is the rout I would suggest if you do elect to try them. (ref) There is very little independent hard evidence that many of these medications given transdermally to cats are actually absorbed in enough quantity to have a positive effect. (ref)  If you elect to use them, I would give the medications a few months trial in any case (if your cat accepts your applying them without a fuss) because you have so few alternative options.

These medications are never curative and rarely effective when other important changes in your cat’s environment and care are not simultaneously made. Cats, like people, can be over-medicated or medicated for the wrong reasons (ref) but you can read more about the medication used as an approach to cat socialization problems here, here and here.

What About A Cat Psychologist?

Discussing you and your cat’s situation with another empathetic person is always comforting. As in humans, basic cat personalities once established in kittenhood do not change. (ref) 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 the situation cannot be improved through their 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 your and your cats. Every cat-to-human relationship is unique and requires a customized approach – not something that can be done by checking off a form or consultations over the internet or phone. Cat owners making decisions on the future fate of an unmanageable pet experience a lot of guilt. At the least, giving these people a try lets you tell yourself that you 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 the neighborhood 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. (rptref)

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 months under the understanding that you will return them, no questions asked, if their relationships and behavior in your home is not what you seek. Once you have given them names, you will find it exceedingly difficult to give them up.

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

My favorite is the sociable, confident, easygoing cat. It will come up to you 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 is curious and will chase a toy or a string. 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 pets. They have loving relationships with their owners and usually get on well with their feline housemates.

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.

Standardized methods to classify a cat’s personality have been developed. You can read them here, here, here and  here.

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 their cats are in a conundrum. If they wait long enough to truly judge the temperament of the cats and kittens that come in, 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. (ref) If they keep cats long enough for them to revert to their true dispositions, other health issues can be discovered that require expensive veterinary care. Not only the cats are stressed by the realities of the situation; it is highly stressful to the people providing their care. (ref) Over the years, I have seen the emotional exhaustion, turnover and negative effects on the general health of the good folks who attempt to assist these animals. (ref1, ref2) It is not that different in other high-stress, emotion-laden jobs that take a toll on your empathy. (ref) Is it any wonder that they are motivated to places as many cats in homes as they can, as fast as they can?

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 pre-existing socialization issues as well.

When it occurs in a household of cats, it is often due to the introduction of a non-compatible cat. Less frequently but also common, it 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 no such event occurred, personality changes are often due to health issues the cat is facing.

When it is an 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.   It can also be due to the many other health issues that older cats face.  Hyperthyroidism, so common in older cats, can cause hyper-excitability and personality changes. Read about that here. Although the mental decline of old age (cognitive dysfunction/ pet Alzheimer’s) is said to occasionally cause aggression, things like loss of litter box training and confusion are more common symptoms. Read more about that problem and other behavioral problems in older cats here and here

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 cat will come from a shelter, spend some time looking over their available cats using some of the methods I mentioned earlier to judge their underlying dispositions. 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 too young. That brings up a whole different set of health issues. (ref)

Be sure the cat is already free of fleas, ticks, internal parasites, ringworm and ear mites. I prefer that the cat’s  health has already been recently checked by their participating veterinarian. There is nothing as disconcerting to a veterinarian as to having to convey bad news to happy clients who drops by with a newly adopted cat – be that anti-social or physical health issues.  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.

Later in the day, go to the store and buy a spacious, high quality pet carrier. Not the cardboard one the shelter will 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.

If you already have other cats at home, those that previously accepted newcomers 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 a preferred location for one of your resident cats. It should be a quiet room in which you can place separate food, water, litter box, and enrichment activities and 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.

I would maintain that situation for about a week – perhaps more if the resident cats or the newcomer appear tense or agitated, perhaps less if everyone remains mellow. After the first day or two, depending on how calm things appear, take two small pieces of your apparel or one of your used small towels . Mark them and stroke each cat down with one of them. Then place the item in a corner of the living areas of the opposite cats. If all goes well, repeat that from day to day until the cats 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 they 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 compete for resources, snacks and toys in an attempt to break the ice. That does not work and is counter productive.
You can read another veterinarian’s  thoughts about introducing cats to each other here.

How Can I Tell If My New Cat or Old Cat Is Uncomfortable In Its New Living Arrangement?

Cats that are uncomfortable with each other rarely interact. When they do, it is often aggressively over possession of choice resources (food, toys, favorite resting area, etc.) One will often leave the room when the other 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.

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