Case Study: Barney — Human-directed Aggression in a Cat

Written by Emily Carl, CCBC CPDT-KA


Summary: As a kitten, Barney’s aggressive behavior was ignored by his family, hoping that Barney would grow out of it. A few years later, when Barney’s family bring home a new foster son, they find themselves unprepared to handle Barney’s behavior towards him. Through providing more space, play, enrichment, and target training, the family were able to help their foster son feel more comfortable in their home, and help Barney feel less triggered to aggression too. 

Subject: Barney

Age: 5 years old

Species: Feline

Breed: Unknown, Domestic Medium Hair Mix

Sex: Neutered Male

Housing: Two-bedroom apartment with a 35-year old man and woman (Marshall and Lily), 8-year-old foster son (Ted), and 5-year-old spayed female cat (Robin). Free-roam except for foster son’s bedroom.


Presenting complaint: Aggression toward visitors and 8-year-old foster son.

Acquired from, and age at time: Local animal shelter, four years earlier at 6 months old.

Medical history: No medical concerns and up-to-date with vaccines. Both cats have had annual veterinary examinations since they were first adopted.

Diet: Wellness wet and dry food, half a 5.5 oz can fed twice daily and dry food free-fed.

Behavioral history

Lily adopted Barney and his sister Robin when they were 6 months old. Lily knew nothing about Barney and Robin’s past except that they were brought into the animal shelter together as strays. Lily let them free-roam the apartment and never saw behavioral issues between the cats.

Since Barney first arrived in their home, Marshall and Lily noted that he closely watched visitors and swatted at them as they passed. They ignored the behavior since he was a kitten and didn’t do physical damage, and they didn’t have visitors often. Barney continued this behavior and it started to escalate once visitors came over more often (when Barney was about 2 years old) and he was now attacking visitors, approaching at the entryway immediately when they arrived, occasionally sniffing and rubbing against their legs and then swatting and hissing if visitors reached down to touch. If they did not reach down to touch and simply entered the apartment, Barney would growl and chase them, swatting at their legs and hissing. Barney watched visitors once they were inside and would swat at their legs if they moved between rooms. This reaction to visitors has been stable since Barney was 2 years old and visitors began coming over more often.

About a month ago, Ted was playing in his room with his headphones on and Barney was lying on the bed next to him, as he often did. Ted stood up, did not notice Barney hop down from the bed, and accidentally stepped on his tail. Barney yowled and jumped at Ted’s torso, bit two or three times, and jumped down. Ted screamed and Barney swatted at Ted’s legs until Marshall and Lily entered and Barney ran out of the room. Ted had a few small bruises and scratches on his legs, but his sweatshirt prevented teeth from contacting his skin. Marshall and Lily reported the incident to Social Services, who said that as long as blood was not drawn from a bite and that this did not occur regularly, no intervention was needed on their part.

Marshall and Lily had two prior foster children since they adopted Barney and Robin, and had never had an issue with Barney attacking them until now.

Marshall has little to no knowledge of cats and has only ever lived with Barney and Robin. Lily fostered two or three litters of kittens over the past decade (before adopting Barney and Robin). Since the incident, Ted was extremely fearful of Barney and would not enter the same room as him. Barney started acting similarly toward Ted as he did with strangers, staring when he checked if he was in the room, running to the door and batting at his feet if he cracked the door open.

First Visit


When I arrived, Lily and Marshall opened the door to greet me and, almost immediately, Barney walked quickly toward me with a vertical tail, tall body, and forward ears/whiskers. He sniffed and started rubbing against my legs. I started to bend over to see more clearly what he was doing and he swatted quickly twice at my legs, hissed, and ran off. Lily and Marshall said that was what he typically did with visitors.

Lily and Marshall gave me a tour of their approximately 800-square-foot apartment, beginning with the kitchen. A water fountain and a bowl about half-full of dry cat food was located at the end of the cabinets. The kitchen funneled into a long, narrow hallway, which led to the bathroom and two bedrooms.

The end of the hallway and kitchen opened into the living room, the most frequented room of the apartment. A large sofa was in the middle of the room next to a 5-foot cat tree where Robin perched. Robin glanced over, then ignored us for the rest of the visit. There were two underbed storage containers used for litter boxes toward the back of the living room. There were also three solo toys — a toy mouse and two crinkly balls — and a feather wand toy on the floor. I asked how often the cats played, and Lily said Barney occasionally batted the balls and mouse around but that Robin didn’t show interest.

Barney sat very tall with stiff posture and slightly widened eyes with partially dilated pupils. He stared at me as I moved around the room. Lily said that was normal and added that if a visitor left the room, Barney would run over, swat at their legs, hiss, and run away. Occasionally he would chase them. I asked if he chased everyone or just some visitors, and Lily said her friend was nervous and yelled if Barney came close, which spurred Barney on. Barney attacked confident people less persistently. Lily said they don’t have visitors as much anymore, but that they warned visitors prior and asked that they don’t touch or look at Barney. They used to scold Barney by yelling “No!” or “Stop!” when they saw him go for visitors but realized it didn’t help, since Barney showed no reaction and, sometimes, even increased frequency of swats or started growling more. The only other attempt to stop or manage the behavior was to close Barney in the bedroom when they had visitors.

The tour continued to the bedrooms. The main bedroom had a large, rectangular litter box against the far wall and a 4-foot cat tree under the window. Marshall closed Barney in this bedroom and we proceeded to Ted’s room. Lily shared that Ted’s room is now a Barney-free zone and Ted said that Barney scared him and that he did not like to be around him anymore.

We left Ted’s room, and Lily let Barney out of their bedroom. We ended our first session seated in the living room discussing the plan. Ted cracked his bedroom door open and peeked into the living room four or five times. When this happened, Barney’s head pricked up and he stared at the door. The first time or two, Ted gasped or let out a high-pitched whine and quickly closed the door. The final few times, Barney ran towards the door and tried to paw at the opening and Ted escalated to a shriek as he quickly closed the door again. I asked Lily if that happened regularly between Ted and Barney, and she said it happened once or twice daily.


Lily and Marshall believed that Barney was unpredictable and bipolar. However, Barney displayed several predictable trends in his behavior.

Any time Marshall and Lily approached the door together without first putting on shoes or grabbing keys to leave, a visitor would arrive. This was a predictor of visitors and alerted Barney to rush to the door.

Barney would first facially rub against visitors’ legs, scent marking and creating a sense of ownership the very moment they entered the room. Visitors reaching toward Barney’s space was a trigger. Barney’s readiness to lunge and swat visitors when they moved from room to room showed spatial awareness and sensitivity to invasion of communal space. This suggested that Barney had spatial insecurity for which he overcompensated and actively tried to assert his ownership when, or before, his space was invaded.

Once visitors entered the home, Barney’s attacks primarily happened in the narrow hallway. Insecure cats, especially those confined to smaller spaces, develop an agitation and defensiveness over what small territory they have. This defensiveness can manifest itself through offensive or defensive attacks.1 When a cat is given a broader sense of territory and confidence, the need to defend the space diminishes. Barney also showed territorial behaviors in the hallway by occasionally scratching at the corner of the wall in the hallway, near where Barney stood when watching visitors.

Lily noted that Ted and Barney previously had a good relationship. Once Ted accidentally stepped on Barney’s tail, he lashed out defensively in what could be a combination of pain-induced aggression, where acute or chronic pain triggers an aggressive reaction, and defensive aggression, in which a cat will show aggression as a response to a real or perceived threat.1

Victim reactions and visitor frequency show another trend. Ted’s peeking through the door and gasping/shrieking, and visitors’ tension/yelling triggered Barney to stalk and treat them as prey. While the initial isolated incident with Ted did not begin with a prey element (as evidenced in the details of the incident and the lack of aggressive behavior seen with other foster children), I believe Barney’s relationships with visitors and Ted had become more similar. The more visitors came over or Ted peeked through the door, the more aroused behavior Barney showed (stalking, body stiffness, pouncing, dilated pupils, etc.). Nervous visitors likely had an increased heart rate. Cats can sense when human breath becomes shallow and heart rate speeds up, and high-pitched sounds can heighten arousal in an already-tense cat such as Barney and cause him to perceive the source as a threat.2

While this appeared to be an issue of territorial insecurity leading to lack of confidence in Barney, medical causes must always be taken into consideration. I recommended that Marshall and Lily consult with their veterinarian about whether chronic pain could be a factor or if the veterinarian had other thoughts as to a medical cause for this behavior.


Negative indications:

  • Barney was overtly aggressive toward visitors upon arrival and moving between rooms.
  • Barney was overtly aggressive toward the foster son in an isolated incident where the child was physically injured and psychologically traumatized. Barney had since shown indications of potential aggression directed toward the child when he peeks through his bedroom door, shrieks, and shuts the door.
  • Visitors’ and the foster child’s emotional fear response heightened Barney’s aggressive reactions.

Positive indications:

  • Barney’s behavior appeared isolated to visitors, especially in the hallway and entryway. The only exception was the foster child once he began to exhibit similar fearful responses as nervous visitors.
  • Barney was able to be safely led and kept in an enclosed room by Marshall and Lily
  • Marshall and Lily shared that they planned to move to a larger home in a few months, which would eliminate the factor of narrow spaces and allow for better spatial separation, as needed.


Intervention recommendations

Consult #1


  • Safety must be considered the first priority in this case, especially since a foster child’s well-being was at risk. I recommended that Marshall and Lily continue keeping Barney separated or at a safe distance from triggers.
  • I recommended that Marshall and Lily continue full transparency with Social Services about Ted’s physical and emotional well-being in relation to Barney.
  • To prevent Ted’s peeking through the doorway while still allowing separation, I suggested a screen door. Marshall and Lily mentioned that, prior to Barney’s attack on Ted, Ted’s door was always open, so this should not compromise privacy and would build trust and maintain safety.


  • I recommended a veterinary consultation to determine if chronic pain or other medical factors could contribute to his behavior.

Environmental modification:

  • Incorporate vertical spaces along the hallway and near the entryway and encourage Barney to frequent those spaces to expand Barney’s space.
  • Offer meal enrichment for dry food rather than free-feeding. Cognitive exercise can refocus the brain, release serotonin for general improved mental health, and lower anxiety to reduce likelihood of aggressive behaviors.3

Behavior modification:

Barney’s aggression seemed like dominance to Lily and Marshall, so I explained how aggression can stem from insecurity. Barney’s sense of owning a limited space and incidence of his immediate space being invaded triggered an aggressive, protective response.

Since Barney displayed a higher energy level and increased tendency to treat visitors and Ted as prey when they exhibited prey-like behaviors, we decided this was best addressed through coaching visitors and Ted through calm reactions and giving Barney an appropriate outlet for built-up energy and predatory instincts.

I explained the natural cat cycle of hunt-catch-kill-eat-groom-sleep and asked that Lily incorporate daily play with Barney, specifically before meals. Since they already had a wand toy that Barney loved in the home, I demonstrated how to move it sporadically in a way that mimicked the actual movements of a bird, in order to entice and engage Barney. According to Pam Johnson-Bennett, “Successful, frequent playtime helps build confidence.”4 So, this would help to drain Barney’s pent-up energy and, most importantly, give him a sense of confidence due to serotonin boosts during play.

I recommended enrichment at least once daily. This would be a mental outlet for Barney’s energy and act as a dopamine booster, helping build confidence and reducing complicating factors such as stress, anxiety, and insecurity. I recommended that they offer meal enrichment like puzzle feeders, especially while visitors were over. I also recommended clicker training as a form of cognitive enrichment.

As a start to clicker training, I introduced the concept of a reward marker, using a store-bought clicker, and practiced for a few minutes establishing this reward marker with Barney. We did several repetitions of a click immediately followed by a treat. After about seven repetitions, I asked Lily to click and pause to see if Barney would look to her expectantly. Once Barney did, Lily rewarded him. Barney picked up the reward marker quickly and was engaged throughout the exercise.

Since Marshall and Lily’s primary concern was the physical and emotional well-being of their foster son, we made it a priority to include Ted in the process. For example, I suggested that he help choose cat perches to incorporate vertical space for Barney and that he help craft puzzle feeders for Barney. Lastly, I encouraged them to have Ted participate in clicker training as long as he was comfortable. While Ted would occasionally feed Barney, it is understood that “the act of feeding a cat can enhance the establishment of a relationship, but it is not sufficient to maintain it. Other interactions (stroking, playing, vocalizing, etc.) are required in the relationship.”5 To accommodate a sense of security while allowing these other interactions, I added that they could stack baby gates in his bedroom doorway so that he could toss a treat to Barney while maintaining distance.

I encouraged Marshall and Lily to watch a free online webinar on cat body language, Maddie’s Fund’s “How to Speak Cat,” as a family activity and a way to empower Ted to understand Barney’s warning signals through body language. This would also be helpful information for Marshall and Lily to help in guiding visitors as well.

Consult #2

Prior this consultation, Lily confirmed that Barney’s veterinarian gave him a clean bill of health. I returned the following week to find that Marshall and Lily had added a perch to the hallway and replaced Ted’s door with a screen door. Barney did bat at my legs once as I walked toward the living room in a much more subtle way than the week prior; this time Barney did not hiss or swat, his body was looser, and he did not approach or leave as quickly as he did the week before. He also did not attack me when I moved from room to room, though he did sit on his perch and continue to observe.

I asked how the relationship-building was going between Ted and Barney and they replied that, while Ted was not comfortable clicker training Barney himself at this stage, he did make a point of watching through him screen door and found the exercise to be very entertaining. They also noticed a complete stop to Barney darting toward Ted’s room since installing the screen door. Initially, Ted still gasped when he saw Barney, causing Barney to approach the door and pay closer attention to what Ted was doing. Ted’s vocalizations stopped after the first day, and they were near a place of ignoring each other while within sight of each other.

Behavior modification:

We discussed Marshall and Lily going to the door as a predictor of people entering the home. I suggested they have a friend come over and have Lily engage Barney with a toy in their bedroom with the door open while Marshall greeted the guest. This would engage Barney in a positive experience at the same time as a visitor’s arrival and help eliminate their joined presence at the entryway as a predictor of visitors. I also asked them to knock and feed Barney immediately afterwards to make knocking a predictor of food, rather than a predictor of a stressful trigger.

We began target training using a target stick I had brought along. I explained that we could use what we started with clicker training to teach Barney to touch his nose to the target. We could then use targeting to guide Barney around the home without ever invading his space. This would create a sense of control over Barney’s movements while Barney simultaneously felt control over his environment, having learned a new skill and chosen to utilize it.

To begin this targeting behavior, I demonstrated smearing a little wet food to the target and holding it immediately in front of Barney’s nose. When Barney leaned forward to touch his nose to the ball to sniff and lick the food, I clicked (which was conditioned the week prior) and delivered a food reward. I asked Lily and Marshall to practice the same exercise, keeping the target no more than an inch or so away from Barney’s face. After about four repetitions, we removed the food from the target and restarted within an inch of Barney’s face, clicking and rewarding when he touched his nose to the target stick. I added that, over time, they could increase distance between Barney and the target stick but that they should do so gradually. I explained that if Barney lost focus or disengaged, they should take a break and try again closer to Barney.

I asked that they continue this practice every day and encourage Ted to participate as well, if he was comfortable. I noted they could elongate the target stick to give Ted some added distance and he could hold the target stick through the crack of the door or bars of a baby gate for added security.

Consult #3

I revisited three weeks later. While Ted was still uncertain of Barney, he was actively excited by targeting. Ted and Barney spent several minutes each day practicing targeting through a baby gate.

Marshall and Lily had a friend come over and practiced the new greeting ritual we discussed. They said this worked beautifully to eliminate entryway attacks. I noticed during my entrance to the home that Barney did not approach the door and I was able to move about the home without being stalked or pawed at by Barney. Marshall and Lily only had two or three instances soon after my last visit where Barney pawed at visitors’ feet. He has not shown visual fixation for the past week.

Marshall and Lily successfully got Barney to target from approximately 6 feet away. Occasionally they needed to start closer to Barney if there was a visitor over. Marshall and Lily found targeting to help give everyone peace of mind and relocate Barney when visitors moved from room to room.


I kept in touch with Marshall and Lily over the next few months. After about three months, they moved to a larger house. During this time, I helped guide them in how to make the transition as stress-free as possible for both Barney and Robin. This involved moving the same cat furniture to similar locations, slowly and gradually introducing both cats into the home (starting with a “base camp” room), and maintaining the same feeding and exercise routine.

About one month after the move, Marshall and Lily noted a “night-and-day difference” in Barney. Barney had plenty of space in their two-floor, two-bedroom home. He rarely spent time in the same room when visitors came over. Lily believed that Ted also found relief in the new home since he no longer had those bad memories associated with his bedroom. While Ted is not comfortable enough to have Barney closed in the room with him, he now often sat in the living room with his foster parents while Barney was present. He also continued his involvement in target training and started to engage in interactive play with Barney using a feather wand. Lily and Marshall felt that Barney was no longer a safety risk within their home.


  1. Frank, D, and Dehasse, J. (2003) Differential diagnosis and management of human-directed aggression in cats. Veterinary Clinics: Small Animal Practice 33:2, 269-286.
  2. Chapman, B. L., and Voith, V. L. (1990). Cat aggression redirected to people: 14 cases (1981-1987). Journal of the American Veterinary Medical Association 196:6, 947-950.
  3. Zebunke, M, Puppe, B., and  Langbein. J. (2013) Effects of cognitive enrichment on behavioural and physiological reactions of pigs. Physiology & behavior 118, 70-79.
  4. Johnson-Bennett, P. (2011) Think Like a Cat: How to Raise a Well-adjusted Cat–not a Sour Puss. Penguin Group USA.
  5. Turner, D. C., Bateson, P.P.G., eds.(2000) The domestic cat: the biology of its behaviour. Cambridge University Press.


Emily Carl (CPDT-KA, CCBC) is the owner of Great and Small Animal Behavior and Training. After years working in shelters and teaching group classes, she now offers private dog training and cat behavior consultations while offering cat nail trim fundraisers and foster/volunteer training for local shelters.

TO CITE: Carl, E. (2021) Case study: Human-directed aggression in a cat. The IAABC Foundation Journal 20, doi: 10.55736/iaabcfj20.6