Abstract

Successfully integrating unfamiliar cats into a shared living environment requires a structured and evidence-based approach. This case study examines the introduction of two cats, Rosie and Caleb, who presented contrasting temperaments and were initially unlikely to form a positive relationship. Over a 39-day period, their integration was guided by thoughtful management, gradual exposure, and applied training techniques rooted in contemporary nonhuman animal behavior research. The case documents key milestones in their social development, highlighting the effectiveness of patience, environmental management, and reinforcement-based strategies in facilitating a relationship. Findings contribute to the understanding of feline social adaptation and provide practical insights for caregivers managing multi-cat households.

Figure 1: Caleb and Rosie

Behaviour History

When 10-year-old male neutered lilac European Burmese, Caleb, became the only cat in the home, his behaviour of excessively attempting to lick the caregivers (cat grooming), frequent crying, and decreased activity indicated the likelihood that Caleb missed his longtime cat companion, Haddie, and was demonstrating behaviours akin to grief (Walker et al., 2016). Caleb had a history of intercat tension with overt agonistic behaviours, including staring, stalking, chasing, swatting, and biting another former cat in the home, Mallory, until both cats were prescribed fluoxetine to facilitate mutual toleration. Two incidents of redirected aggression resulted in bite wounds to the caregiver. Introducing a companion cat to Caleb could benefit his wellbeing, but had the potential to be a stressor to both cats, as well as the caregivers.

Three months after Haddie’s death, Rosie, a 2-year-old female spayed red European Burmese was adopted. In her former home, she expressed affiliative behaviors toward other cats such as nose-touch, allogrooming, and resting together. But several months before adoption, when Rosie spent time away from her home, for unknown reasons she began to fear people. Avoidance behaviours included fleeing and hiding instead of greeting people, which is unusual for European Burmese (Selonen et al., 2019). Rosie’s history is partially known but not detailed for privacy purposes.

A study of 2,492 multi-cat households emphasized the importance of well-managed introductions, where 87.7% observed intercat conflict, of which 73.3% stated conflict started when a new cat was introduced (Elzerman et al., 2020). When introducing cats, in addition to environmental management, systematic desensitization is typically utilized by gradual exposure to each other’s four senses individually — hearing, smell, sight, and touch (Bradshaw & Ellis, 2016). Behaviour modification strategies utilizing operant conditioning can be beneficial during introductions to reduce stress, increase affiliative behaviours and enhance wellbeing (Pratsch et al., 2018, Savastano et al., 2023). During these processes cats are conditioned to thrive together by building resilience — the ability to recover from the negative impact of environmental stressors (Bhambree & Murphy, 2023).

The introduction of Caleb and Rosie took 29 days to achieve mutual displays of affiliative behaviours without the need for continual monitoring.

Negative Indications

• Caleb was 10 years old.
• Caleb practiced agonistic behaviours of stalking, chasing, and swatting for 8 years.
• Anti-anxiety medication was necessary for Caleb to tolerate former housemate Mallory.
• Rosie displayed avoidance behaviours of fleeing and hiding in the presence of people.

Positive Indications

• Rosie was 2 years old.
• Caleb displayed affiliative behaviors of allogrooming, sleeping intertwined, and social play with his former housemate Haddie.
• Caleb’s behaviour of crying, decreased activity, and excessively attempting to lick his caregivers (cat grooming behaviour) could be relieved by a feline companion.
• Caregivers have improved skills in introducing cats.
• The five pillars of a healthy multi-cat environment were implemented, including safe places (Rodan et al., 2024).

Bringing Fearful Rosie Home (Days #1–5)

Both cats had safe rooms with necessary resources: a litter box, water, food, a scratching post and pad, and places to sleep, rest, and hide. Enrichment included toy mice, balls and food puzzles. Rosie’s room became her territory where she could feel secure and lower her stress after exploring the house or meeting Caleb. Her door was kept closed with a baby gate in the doorway to prevent either cat from dashing in or out when a person entered or exited the room, avoiding possible intercat tension. Caleb did not indicate he would jump the gate, nor did Rosie until day #10 when the gates were double-stacked, which will be discussed.

In outdoor cat colonies, agonistic behaviors are directed toward unfamiliar cats and acceptance of non-colony cats occurs only after numerous interactions (Crowel-Davis et al., 2004). Since cats lack appeasement behaviors and the skill set for conflict resolution, implementing a gradual introduction process, including the use of barriers, decreases the likelihood of agonistic behaviors and increases the likelihood of affiliative behaviours (Rodan et al., 2024).

Day #1. Rosie’s arrival

Upon arrival in her safe room, Rosie immediately scurried behind the daybed. She was left alone with the night light on, a pheromone diffuser plugged in, and soft, calming “Through a Cat’s Ear” music playing. Throughout the evening, she was found in the same spot motionless behind the daybed, wide-eyed and crouched over tucked legs, indicating she was “shut down” (Overall, 2013). The litter box was unused, although three feet from her. Viewing Rosie from a distance, after seeing her blink, lean, or look away, the caregiver said “Good girl,” slow eye-blinked back to mimic a cat’s relaxed, non-threatening interaction (Bradshaw & Ellis, 2016), and quietly left the room. If Rosie wanted distance from the caregiver (averser), then when she saw the caregiver, she predictably would increase the likelihood of slow eye-blinking (relaxed behaviour), leaning, or looking away, for the averser to move away from her (negative reinforcement) (Adelman, 2015; Heidenreich, B. 2020). To be cared for and trained, Rosie needed to overcome her fear of her caregivers before she could meet Caleb.

Day #2–3. Rosie is not a happy cat

A routine was started to reduce stress and to strengthen resilience by interacting with Rosie in a manner that was predictable to her. Before entering Rosie’s room, a signal was always given so she would know a person was approaching — a quiet knock, knock, knock and soft greeting, “Hi sweet girl.” On her first morning, Rosie was still wide-eyed with dilated pupils, crouched behind the daybed, her body half under the urine-soaked bed sheet draped over her. The litter box was untouched. Her food was uneaten, all indicating stress.

Figure 2: Day #2 (morning) Fearful Rosie behind the daybed.

To entice Rosie to eat, four times a day wet food was warmed with the appetitive Fortiflora probiotics sprinkled on top. Daily, the calming nutraceutical L-theanine was used (Dramard et al., 2018), (Note: always follow veterinarian guidance on using nutraceuticals and psychotherapeutic medications.). Announcing arrival and glancing at Rosie from a distance, similar negative reinforcement interactions were used as on Day #1. A treat was left within her view and wet food was placed farther away from the litter box. Kibble was always available in a food puzzle. There was a switchover from negative reinforcement to positive reinforcement once Rosie was relaxed enough to eat in the presence of a caregiver (Taylor and Zeman, 2020).

By noon, Rosie moved to a softer location — the lower mattress under the daybed. Although she had not eaten a meal yet, the treats were eaten and she used the litter box, indicating she was slightly more comfortable in her territory.

Figure 3: Day #2 (noon) Wide-eyed Rosie under the daybed.

Figure 4: Day #3 Rosie is under the daybed, with eyes slightly relaxed.

By evening, although hiding on the lower mattress, Rosie’s eyes were more relaxed, almond-shaped, and squinting. When the caregiver presented a bent finger in greeting to determine if she wanted to interact, Rosie leaned away, widening her eyes. She was saying “No.” The caregiver moved away, slowly blinked, and glanced away; as Rosie relaxed, the caregiver softly said, “Good girl,” left a treat and departed the room. The finger was presented far enough away for the cat to choose whether or not to approach and sniff. A cat will approach and facial rub if desiring interaction, while leaning or moving away indicates no desire to interact (Bradshaw and Ellis, 2016).

Because Rosie was hiding, a motion-detecting camera was installed in her room on Day #2. The benefits included:

• • The ability to monitor Rosie’s eating, drinking, using the litter box, playing, scratching, grooming, increasing movement, and marking her territory.
  • The videos revealed Rosie roaming until she heard knocking. Then she quickly hid.
  • The videos showed a repetitive behaviour: After Rosie ate, she pawed as if to cover her empty wet-food bowl. This could be addressed by removing the bowl sooner to avoid frustration.
  • Rosie’s reaction to Caleb’s scent on a glove was observed. She did not hiss, but instead ate the treats nearby and later played with the glove.
  • Caregivers felt less stress seeing Rosie display species-typical behaviour.

Figure 5: Day #3 Night view of Rosie, litter box, water, food, and the daybed.

Day #4. Scent exchange and Rosie peeking at caregivers

Spending time in Rosie’s room without interacting with her, the caregivers spoke softly and examined videos of Rosie. Since Rosie’s body language on day #3 showed an increase in species-typical behaviour indicative of reduced stress (Herron et al., 2020), and Rosie was eating treats, it was time to transition from R- to R+ to help Rosie habituate to people.

The videos reassured the caregivers that Rosie’s confidence was increasing as she moved around the room without hesitation, resting on top of the daybed and the window shelf. She was also depositing pheromones around her territory by scratching the sisal post and rubbing her cheeks against various items, which is believed to aid a cat in feeling secure in the living space (Herron et al., 2020).

Daily scent exchange was started as outlined in The Trainable Cat by Bradshaw and Ellis (2016). As noted above, after collecting Caleb’s scent on a glove, it was placed in Rosie’s room. Via video, Rosie was observed playing with the glove without hissing, indicating that Caleb’s scent was not a stressor.

At noon, the caregivers positioned themselves as far away as possible from the food and spoke gently to Rosie. Slowly, she slinked from under the bed, staring nervously with wide eyes and upright ears as she gradually crept farther away, watching the string toy the caregiver was moving like a snake. From this day forward, Rosie would eat food within view of the caregivers.

Figure 6: Day #4 Wide-eyed Rosie peeks at the caregivers.

Day #5. Rosie rubbing the caregivers!

At the noon meal when Rosie came out from under the daybed, instead of eating the wet food, she pressed along the wall, inch by inch, hesitantly moving closer to the caregiver sitting cross-legged on the floor. Rosie rubbed her cheek against the extended, motionless hand, quickly allowing chin and cheek petting while softly purring. Rosie turned to the other caregiver sitting still in a chair, then brushed against the lowered hand, and quickly flipped on her back, wiggling back and forth, indicating a breakthrough of relaxation in the presence of the caregivers.

Description: Day #5 Rosie seeks social attention.

Rosie chased a fishing pole toy back and forth across a fleece blanket covering the caregiver’s lap and legs, helping Rosie have a positive association with the caregiver in addition to exercising. Research suggests that play can help cats reduce stress-related behaviours (Delgado, 2024; Henning et al., 2023). Rosie increasingly sat on laps. When a hand was presented, Rosie leaned in for a head, chin, cheek, or neck rub, responding with purring, kneading, head bunts, relaxed almond-shaped eyes and rolling on her back, indicating she was comfortable.

Still skittish, Rosie fled when anyone attempted to pick her up. She was conditioned to give consent (through operant conditioning of an opt-in and opt-out behaviour) for being picked up for care such as grooming or moving her from one location to another (Feyrechilde, 2024; Jones, 2023). Since Rosie repeatedly leaned into a presented hand for head, chin, cheek, or neck rubs, this tactile reinforcer was used during gradual systematic exposure to being lifted.

Cooperative care for handling:

• Extended hands were shown to Rosie and a mouth noise was made (a signal to her that she was about to be touched). Predictive cues can increase predictability and decrease stress (Jones, 2023).
• Rosie remaining near the hands indicated she was giving consent to be touched and eventually picked up (proximity for opt-in). If she moved away or slightly pushed away from being touched, she was saying “No” (increased proximity for opt-out), so touching was stopped. This allowed Rosie to have control over interactions.
• Her flank was touched, followed by chin rubs, which she leaned into.
• A palm was slipped under her belly, and then chin rubs were given.
• She was lifted off the ground two inches for one second, set down, and given chin rubs.
• Gradually, the distance from the floor was increased. After being placed on the floor, she received chin rubs.
• Gradually, Rosie was held a few seconds more each time. She received chin and neck rubs while being held. Purring and the absence of a struggle to escape indicated success.

Interactions with Rosie were consistent and predictable, while she was given the choice to engage. Her resilience was increasing, as she was overcoming her fear of people. From this visit forward, Rosie immediately greeted the caregivers when they entered the room.

Building Confidence and Room Exchanges (Day #6–10)

Day #6. Operant conditioning

Rosie was still expressing avoidance behaviour, running away when anyone stood or when she heard a loud noise. With operant conditioning and positive reinforcement, the goal was to increase Rosie’s confidence as expressed by affiliative and relaxed species-typical behaviours as well as behaviours beneficial for caregiving (Savastano et al., 2010). Clicker training was introduced using lickable cat paste, such as Churu or Catit (unconditioned reinforcer). Because the sound of the clicker (conditioned reinforcer) elicited flinching, her caregivers muffled the sound, which lessened Rosie’s startle response. She quickly habituated to the sound of quieter clickers (Clik-R and Clicino). A verbal marker could have been used, but with the unique sound of the clicker, desirable behaviours can be concisely marked. Rosie decreased hiding and increased time relaxing on top of the daybed and the window shelf as well as increased approaching, allowing caregivers to touch her.

Figure 7: Day #6 Relaxed Rosie enjoys neck massages. Her eyes are almond-shaped with constricted pupils.

Daily multiple two-minute sessions included:

• Touch a target stick. The first behaviour taught was touching a target stick since it is easy and would be used during group sessions.
• Come when called. This would be used for redirecting attention away from Caleb.

On Day #7 other behaviours were added:

• Go to the mat.
• Wear a harness. A harness would be used when the cats were initially in the same room, but training began on Day #8, to give Rosie more time to adjust to being touched.
• Enter a carrier.
• Tolerate being picked up and paw handling for nail trims. See protocol from Day #5.

Day #7. Room exchanges

Rosie was introduced to one new room each day, while Caleb was closed in a different room. After Rosie was comfortable inside the carrier, it was used to transport her so she would not be overwhelmed by roaming an entire unfamiliar house. In each room, Rosie readily chased toys, ate treats, rubbed against walls, and used scratching pads, depositing her pheromones, making the house her territory. Caleb would gradually detect her scent throughout the house. When they would meet, they would be somewhat familiar with each other. A group scent would be established when each cat chose to rest in a location the other cat had rested.

After Rosie was closed inside a different room, Caleb’s door was opened. He chose to enter Rosie’s safe room, carefully examining everything inside without hissing. He readily ate from her food puzzle. A target stick was presented for him to touch and receive the high-value reinforcer, a lickable cat paste. This was a comfortable, familiar, relaxing behaviour for him. Caleb was then ushered to another room, closed away from Rosie before she returned to her room. Room exchanges helped both cats habituate to each other’s scent.

Inside her room, Rosie began examining the crack below her closed door. This was the first evening Caleb saw parts of her body and directly heard and smelled her under the door. He hissed. Even though there was a baby gate in place, a thick towel was added at the base of the door to control exposure. (A door sweep is recommended.) It is important to manage the environment to avoid eliciting an undesirable response. Initially, when Caleb’s attention turned toward Rosie behind the door, he was given his favorite treat. Caleb would benefit from counter-conditioning when his detection of Rosie would be paired with his receiving treats. Gradual desensitization, or exposure, while Caleb stayed calm was the next step. When Caleb looked away or moved away from Rosie, good things happened, such as receiving a treat, which is further explained on Day #8-9. Breaking eye contact between two cats and teaching them to walk away will decrease threats between cats (Horwitz, 2018; Overall, 2013).

Day #8–9. Caleb, engage-disengage at the door

Controlled exposure to hearing Rosie and seeing her paws under the door:

• Rosie was in her room, her door closed, and the gate removed.
• Caleb was in the hallway.
• Rosie’s wet food on a silicone hot pad was slipped under the door.
• Caleb watched Rosie’s paws coming out under the door. He did not hiss.
• He received lickable cat paste.
• Caleb was called to the mat, 6 feet away.
• His behaviour was reinforced with lickable cat paste.
• He approached the door without hissing.
• He was cued to the mat to sit.
• His behaviour was reinforced with lickable cat paste.
• This was repeated multiple times.
• Additionally, Caleb staying on the mat or looking away from the door was reinforced.

Engaging and disengaging with Rosie without Caleb hissing or swatting and then walking away were positive steps, indicating that when Caleb saw a new cat in his territory, a potential stressor, his resilience increased.

Day #10. Rosie is ready to escape her room

Caleb had his yearly vet visit, so he was given a break from cat interactions. His blood test results indicated he developed pancreatitis. Although he was asymptomatic, health issues could contribute to behaviour problems. This is why it is important to address feline health before training.

The routine of room exchange, interactive play and training with Rosie continued. She relaxed in multiple locations, including sunny spots where Caleb regularly rested. When her door was opened, she was eager to jump the gate. She had a complete change in confidence since her first night home, signifying it was time for the next exposure step.

The Exposure – First Full Body View (Day #11–12)

Day #11. View from a distance

Two-minute sessions of engage-disengage training occurred similar to day #9, but with “look, then look away.”

• Caleb saw Rosie’s paws poking out under the door. He hissed.
• Caleb was called to his mat (increased distance kept Caleb below threshold).
• His behaviour was reinforced with a treat.
• He looked at Rosie’s closed door.
• His name was called.
• He looked at the caregiver.
• His behaviour was reinforced with a treat.
• Caleb looked to the door and then looked back at the caregiver without his name being said.
• His behaviour was reinforced with a treat.
• This was repeated multiple times.

Caleb regularly watched Rosie’s paws under the door without hissing. He relaxed in the hallway with his legs out, belly exposed, and eyes half closed. This behaviour was reinforced with treats and praise. His calmness indicated he was ready for a full-body view of Rosie.

The first full-body view session was kept brief to reduce the chances of reaching threshold. Here is how this was arranged:

• A gate was in the bedroom doorway.
• The cats were stationed at a great distance from each other to reduce potential tension.
• Caleb was on a shelf in the hallway.
• Rosie had her back to Caleb at the far end of her room.
• As Rosie ate food, Caleb saw her entire body.
• Caleb received a treat.
• Caleb looked at Rosie and then looked at the caregiver.
• His behaviour was reinforced with a treat.
• This was repeated multiple times.

When Rosie approached the door, the caregiver would close it. The door was opened after Rosie returned to eating (Fisher, P. 2020).

Description: Day #11 Caleb has a full-body view of Rosie.

Day #12. First nose-to-nose greeting

When left alone in her room, Rosie began increasing her vocalization, evoking Caleb to listen at her door. He cried in a gentle voice, similar to how he vocalized to the caregivers.

In the morning, two-minute engage-disengage sessions were performed like Days #8–9. Caleb did not hiss when he saw Rosie’s paws under her door, and he readily looked away and moved away from Rosie. This was an indication to have another session with Caleb seeing Rosie in full-body view.

The second full-body view session was set up the same as on Day #11. This time after eating, Rosie was so fast rushing to the gate, that she jumped it and fled down the hallway before the caregivers knew what was happening. To prevent Caleb from chasing Rosie, lickable cat paste was frantically shoved in front of his mouth. Fortunately, eating the lickable cat paste was of higher value to Caleb than a chase. As Rosie was returned to her room, Caleb looked at her and expectantly looked back at his treat, which he then received in abundance.

As any consultant would do, the antecedent arrangement was reassessed. Caleb was marvelously adjusting to Rosie, whereas Rosie was now the active cat needing impulse control. Immediately a double-stacked gate (a screen or glass door could also be used) was set up in the doorway so Rosie could not jump out of the room. It would have helped if Rosie had been in a harness during the previous session. Sessions were implemented with Rosie ping-pong approaching the gate and then moving away. This would teach her to avoid rushing at Caleb so he did not feel threatened by her.

Figure 8: Day #12 Double gate with Rosie’s relaxed stretching.

This is how engage-disengage was done with Rosie:

• Caleb played or trained with a caregiver on the hallway floor. He could watch Rosie if he chose.
• Inside the bedroom, Rosie approached the double-stacked gate.
• Rosie was called away from the gate.
• She moved away from the gate.
• Her behaviour was reinforced with wet food.
• This was repeated multiple times.

Rosie’s wet-food meals were rationed for 10 to 15 trials. Neither cat hissed during these sessions. Otherwise, the view would need to be partially blocked. Rosie had gentle vocalizations, tail up in a question mark, and stretched her back leg out in the air in a relaxed pose.

Description: Day #12 Rosie watches Caleb walk by the gate. Both cats have their tails up.

Description: Day #12 Caleb & Rosie are training engage-disengage at the gate.

During setup for the 6 PM engage-disengage training, Rosie and Caleb nose-touched for the first time. Neither cat hissed. Rosie had gentle vocalizations, tail up with curled tip, almond eyes, ears up, and walked confidently to greet Caleb. After 20 minutes, Rosie excitedly rushed to Caleb at the gate. He swatted and hissed. The session ended on a positive note with each cat being called away from the gate and given a treat. Caleb’s stress indicated that he was pushed too far working on distance, duration, and intensity.

Description: Day #12 Caleb swats and hisses when Rosie rushes at him.

The session before bedtime included a nose-touch greeting without hissing. Cuing a variety of easy, familiar behaviours, such as touching a target stick was woven into daily training, while both cats could see each other at a distance. Later, this would be used during group sessions as the cats gradually sat closer to each other. It would be a predictable activity that builds resilience.

Training without a Barrier (Day #13-29)

Day #13. Beyond the gate — first contact

Continuing with room exchanges, Rosie, wearing a harness, readily explored the entire house. Individual training continued with her, especially for handling. With the stacked gates in the open doorway for extended periods, the cats could choose whether to approach or observe each other.

Both cats’ body language indicated relaxation during the morning and noon sessions at the gate. In the hallway, when Caleb saw Rosie, he was lying on his side with his legs out and eyes squinting. Rosie readily approached Caleb multiple times with her tail up, offering gentle vocalizations, and pawing through the gate. Neither cat hissed upon nose-touch. Both cats moved away from the gate when called, indicating the caregivers could train without a barrier.

Figure 9: Day #13 Rosie & Caleb greet each other at the gate.

Figure 10: Day #13 Rosie saw Caleb. Her tail is up with the tip curled.

The first training session without the barrier occurred before the 6 PM feeding. Caleb was in a harness, but not Rosie, which was an oversight. A towel was within reach for safety if their body language, including a threatening stare-down, required breaking eye contact between the cats or separating them. Since Rosie was comfortable roaming the home, the spacious living room was chosen for the beyond-the-gate behaviour modification training.

Short sessions of engage-disengage training were performed. Caleb was stationed on a raised platform, since Rosie was the active cat and Caleb was the quiet cat, which was surprising since in the past he chased Mallory. Rosie was to follow a flirty toy while Caleb watched from a distance and habituated to her movement. Unfortunately, Rosie was more interested in Caleb than the toy. She jumped onto the platform with Caleb. Caleb was immediately given lickable cat paste. It was a huge win that Caleb did not hiss or swat at Rosie. Immediately a switch was made to luring Rosie with lickable cat paste. Caleb was given a treat after he looked away from Rosie or continued sitting in place. He successfully did not stare at or stalk Rosie.

Although the session was messy, overall, it went well. Without a barrier, Caleb did not get over-aroused watching Rosie move, and he tolerated her invading his space. He continued to look away and eat, which indicated that he was below threshold, not stressed. Having individual interactive playtime with each cat before the session could have lessened their energy levels. Having Rosie in a harness and a leash would have prevented her from rushing Caleb, and this session made it clear that Rosie’s impulse control required work. Better preparation with high-value treats (lickable cat paste) for both cats would have helped. Empathy is needed with clients who are in a similar situation — nervous about our cats’ initial interactions without a barrier — a high emotional state affects clear-thinking ability.

Description: Day #13 First contact without a barrier. Caleb is stationed high while watching Rosie and then looks away.

Description: Day #13 Caleb is stationed high while watching Rosie. To lure Rosie to move, lickable cat paste instead of a toy is used.

Day #14-16 Reestablishing a daily life routine

The caregivers could return to a daily life routine, monitoring the cats’ gradually increasing time together, since both cats frequently approached each other at the gate with relaxed body language and without hissing. Wet-food meals were fed on opposite sides of the room with each cat in their high place. When the caregivers watched TV, Caleb relaxed in a lap while keeping an eye on Rosie as she either rested or chased string toys. Caleb was given treats or praise for looking away from zippy Rosie, while Rosie’s attention was directed away from Caleb to avoid conflict. But if she moved too close, Caleb occasionally hissed or swatted. Hissing is normal repelling behaviour, but it indicated that continued gradual exposure was necessary. Occasionally, with relaxed eyes, Caleb would sit next to Rosie, evidencing that resilience and the social relationship continued to improve.

Description: Day #16 Redirecting Rosie’s attention away from Caleb.

Description: Day #16 Redirecting Caleb’s attention away from Rosie.

Initially, interacting without a barrier, both cats wore harnesses with leashes attached. But as the cats appeared more relaxed, the harnesses were removed. Although harnesses helped manage the cats’ interactions, in my experience having a harness on may suppress a cat’s desire to walk or run, and then without the harness the inhibition could disappear, resulting in an undesirable chase.

Day #17 Slow down

Rosie approached Caleb with her tail up, tip curled multiple times. Caleb tolerated Rosie joining him on the caregivers’ laps. Caleb was often relaxed, lying on his side, legs out, and belly exposed, but monitoring was continued. When he looked away from Rosie or sat peacefully next to her, he received treats, chin rubs or praise. Relaxation builds resilience.

Rosie would run fast around the house, passing by or approaching Caleb, occasionally eliciting arousal in Caleb. On one occasion he expressed social tension with posturing, tail-twitching, wide eyes, dilated pupils, and head turned sideways as he stared at Rosie. Slowly, he moved low to the ground, stalking her (Rodan et al., 2024). Redirecting Caleb’s attention away from Rosie was not successful, so he was put in his safe room, allowing his arousal to lower. Later a small puddle of urine was found on the sofa, signifying exposure time with the cats together needed to be shortened.

Figure 11: Day #17 Caleb and Rosie rest together on the caregiver’s lap.

Day #18 Rosie Readily greets a visitor

For socializing the cats, visitors offered treats after cuing behaviours — wave, sit, or touch a target stick. Rosie immediately greeted her first visitor, Heleena, and after eating treats, both cats rested in the chair with her. Great progress considering Rosie regularly hid from unfamiliar people 18 days earlier.

Later that day, Rosie groomed herself while lying next to Caleb. With flattened ears, he kept watching her through his narrowed eyes. Rosie’s paws gradually rested on him. Eventually, he departed, without hissing or swatting.

Day #19–21 “Let’s Walk” and social play

With increasing relative frequency, the cats rested and walked around the house together while being cautiously monitored. Whenever a chase started, the interaction was allowed if body language indicated play — tails up with a bent or gentle waving tip (without being puffed), wiggling rumps, lack of vocalization, and taking turns initiating contact (Rodan et al., 2024). Occasionally, Caleb’s arousal increased when Rosie ran: His tail would puff, pupils dilated, and ears flattened. Then, within seconds of intense staring and posturing with his head tilted, he would chase Rosie as she fled. With her eyes wide and tail puffed, she would hiss or howl, cowering in a hiding spot as Caleb swatted or bit her. Fortunately, he only has two teeth. Caregivers redirected Caleb away from Rosie, calling him to his safe room to decompress.

Caleb needed to learn how to interact with Rosie in a non-threatening manner and to habituate to the stimulus of Rosie running. Social tension would be avoided if Caleb interacted with Rosie predictably, without staring, posturing, swatting, or biting. Similar to parallel walking dogs during introductions (Horwitz, 2018), the exercise I call “Let’s Walk” was begun to gradually desensitize the cats to each other’s movement while giving them something enjoyable to focus on such as high-value treats. This exercise would only be performed when both cats were calm in each other’s presence, never when they were overly aroused. A towel was carried over the trainer’s shoulder in case over-arousal necessitated blocking staring or required physical separation. It was never needed.

Here are the steps for the “Let’s Walk” protocol:

• Both cats were cued to walk toward the trainer, “Let’s Walk,” which they knew from harness training.
• Caleb and Rosie walked, choosing the distance from each other where they were comfortable.
• After a few steps, both cats received lickable cat paste or wet food.
• If Caleb moved to the lead, the direction was changed so Caleb could view Rosie moving.
• Gradually, the distance and speed (intensity) of walking increased before giving the treats.
• The cats could choose to leave.

Description: Day #19 Caleb and Rosie “Let’s Walk”

A rise in social play began. Without being over-aroused, each cat took turns moving close, tapping the other (cuffing), then retreating or wrestling, including numerous pauses. Neither cat hissed, and they didn’t have dilated pupils or puffed tails (Rodan et al., 2024). Rosie vocalized softly when being pursued, but Caleb retreated to a location where he would lie down, relaxed legs extended and belly exposed.

Figure 12: Day #20 Social play.

One very intense chase resulted in Caleb cornering Rosie in a closet as she screamed. This raised concerns that the incident might necessitate restarting the introduction process, potentially impacting their ability to express affiliative behaviours. Caleb was put in his safe room to decompress. Later that evening, he was let out, wearing his harness. While the caregivers watched TV, Rosie approached Caleb as he lay curled up, sleeping. When Rosie settled beside him, he cracked open an eye, peeking at her, and then went back to sleep. Rosie recovering from her fear when Caleb chased her, and her choosing to rest with him, indicated she was developing resilience.

Day #22–28 Group sessions

To further lower Caleb’s desire to chase Rosie, an “antecedent control tactic” was added: a way to reduce the likelihood of chasing Rosie when she runs by adding enrichment that will be a more appropriate outlet to satisfy this desire. Mikel Delgado, in her book, “Play With Your Cat!” (2024) suggests play before meals can help cats relax, better preparing them for grooming or rest. Since the anticipation of food can lead cats to show “bursts of activity” called “food anticipatory activity.” 10-minute interactive play sessions with each cat were added before meals. Caleb was able to satisfy his desire to hunt and eat afterward, resulting in decreased stalking of Rosie.

Group sessions helped the cats adjust to each other. These went like this:

1. The cats touched separate target sticks when the gate was between them. Reinforcers were given.
2. Positioned at a distance to stay below threshold, the cats touched separate target sticks without the gate.
3. Reinforcers were given only after both cats touched their target stick.
4. As the cats relaxed, the distance between the cats was gradually decreased.
5. “Let’s Walk” and playing with toys in the same room continued.

The gate was permanently removed as the days progressed with increased social play and without Caleb being over-aroused.

Day #29 Feline friends at last!

On this night, for the first time, both cats slept with the caregivers. There was a play-hunt session and feeding for the cats before bedtime. A night light was left on to monitor night interactions. Initially, Caleb chased Rosie off the bed, so he was placed in his room for five minutes. Upon returning to the bed, he left Rosie alone as she rested several feet from him, but by morning she was snuggled next to Caleb. Throughout the day, the cats playfully chased each other, expressing social play with reciprocity without over-arousal or hissing.

The caregivers decreased vigilant observations as Caleb and Rosie expressed increased mutual displays of affiliative behaviors including sleep-touching, allogrooming and allorubbing. A social bond developed between Rosie and Caleb as well as between Rosie and her new caregivers (Rodan et al., 2024).

Figure 13: Day #30 Caleb & Rosie relaxed together.

Description: Day #39 Caleb & Rosie social play.

Purring Playmates and Cat Cuddles

It has been over a year since fearful Rosie met feisty Caleb. Today they seek each other out to wrestle, chase playfully, allogroom, cuddle, and sleep together. This may not be the outcome for every introduction. There is still a safe room to handle the rare over-arousal recovery times. But cat caregivers can improve the probability of successful introductions. It requires patience, diligence in separating the cats, and slow, systematic exposure to each other while providing opportunities for choice and control. Building resilience during introductions helps cats have a healthy relationship with each other and a close bond with their caregivers.

Acknowledgments

I thank Eileen Anderson, my mentor during the IAABC Foundation Writing Mentorship course, for her guidance and input on this article. I express deep gratitude to Erin Jones, IAABC Foundation Journal Director, for her invaluable assistance in editing for scientific and technical accuracy.

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Victoria is a cat behavior consultant and owner of Clever Cats Livonia. She holds a bachelor’s degree in medical technology, a diploma in feline behavior science and technology from CASI, and is an Elite Fear Free Certified Professional. She shares educational information about feline care and training through her social media platforms and volunteers with a local shelter, fostering, training cats, and mentoring.