Introducing Foster Pets to Resident Pets

With the arrival of three new foster kittens to our home this spring, I’ve been thinking about the best way to integrate foster pets into a home while also keeping in mind the needs of resident pets. What should happen after the quarantine period? Should the foster pets be kept permanently apart from the resident pets? Should the new pets be immediately integrated with the resident pets, and left to work out any issues among themselves? Or is there a middle ground involving slow and careful introductions? In this article, I’ll share both my family’s personal experiences and the cumulative knowledge shared with me by various pet foster parents.


Whether dogs or cats were being fostered, a handful of pet foster parents favored quick integration, while the majority preferred slow introductions. The latter surprised me because I expected the cat foster parents would say that they never introduce the foster cats to their cats, and I expected the dog foster parents would say that they favored quick introductions. Why did I have these expectations? Because the stereotype is cats are territorial and dogs are social.

I was also surprised that the dog and cat pet foster parents had different reasons for preferring slow introductions. The dog foster parents used slow introductions because many of the dogs they fostered came with “baggage”. Some had aggression issues, some came from puppy mills or long-term residence in shelters, and some had endured stressful travel to reach their new foster home. Then there were the senior dogs who had spent their whole lives with one family and were overwhelmed by the recent upheaval in what had been a life of comfort and predictability. In contrast, cat foster parents preferred slow introductions when they expected the foster cat to be with them for a long time, which was often the case for adult cats. In contrast, foster kittens were often not introduced to resident pets because they’re so adoptable (and because they are often accompanied by a protective mother, and because they’re more likely to have illnesses and those illnesses are slow to manifest themselves).

Although the majority favored slow introductions, they varied in their ideas about how to conduct those introductions. Katie Allan Sample said that she abides by the 3-3-3 Introduction Rule, which she explained this way: “Three days to feel comfortable in a new environment, three weeks to adjust to new people and dogs and to start to see new environment as a safe place, and three months to accept new family and truly relax and learn the house schedule/rules.” At each step, Katie said, she sees more and more of the foster dog’s personality come out, as well as more and more acceptance of newcomers by the resident dogs. “With my senior Gracie each step is super obvious,” Katie said. “She avoids the new dog the first few days. Then after a few weeks, she’ll allow them to sniff and will sit in the same room. Once the new dog had been here a few months, she’ll play and relax around them.”

Sarah Parker and her husband make sure one of them will be home for the first couple of days to ensure a smooth transition, while Amy Van Gerpen’s family typically don’t allow any contact for several days. When introductions eventually do happen in Amy’s home, new foster dogs are first given the chance to smell her other dogs’ stuff. After that, introductions happen through a baby gate and then through leashed meet-and-greets outside in the yard one dog at a time. Shelli Zundel noted that their family’s introduction process includes walks, pet gates, kennels, separate dinners and potty breaks, before the foster and residents meet face to face in the yard.  “We also establish kennel training immediately so the new pup has a safe place that is theirs, and theirs alone. Within a week, most dogs are well adjusted,” Shelli said.

Katie gave an example of why pet foster parents need to take things slow: because a foster pet becoming comfortable in its new home doesn’t mean it’s ready for everything. She met another person’s foster dog that was considered friendly with people and dogs.  “They let him off leash at the park and he attacked me and my dog who were both sitting down. They had him a little over a month. He’d spent his entire life before that on a chain and wasn’t ready for off-leash at the park. Don’t rush it and set your foster up for failure.”


Despite slow introductions be favored by most pet foster parents, some dog foster parents have experienced success with allowing dogs to sort it out themselves.  Hindy Pearson, who has fostered mostly senior dogs, said that she simply brought fosters home and immediately integrated them into the household. “There were issues with them getting used to regular walks so they didn’t have to pee in the house, but thankfully things went smoothly each time in terms of adjusting and getting along.”

Jayne Sebbey leans more towards a flexible approach, explaining that the process can depend on the personalities and backgrounds of the foster dogs and the resident dogs. She introduces fosters and residents on neutral territory such as the front yard. Then she continues with supervised introductions for a week until a daily pattern is worked out and everyone knows what to expect. She recommended taking cues from the resident pets.

Turning now to cats, the majority of foster parents I talked with noted that their decision on whether to introduce or keep cats separate depended on how long they expected to have their foster cat. Emilia Evans has fostered twice. The first time was for a cat that she expected to adopt if things worked out, so she followed normal protocol for integrating a new cat into a home. On the other occasion, she only expected to the cat for only a couple of months. “I didn’t try to integrate her,” Emilia said, “because she isn’t a big fan of other cats and I knew she wouldn’t be a long-time resident.”

Sarah’s experiences echo that of Emilia. “My cat Goose isn’t the most welcoming. We keep the cats separated and, depending how long we have them, Goose either leaves them be or he tolerates them.” Sarah shared that their latest foster cat had been with her family for a year. “She was fearful and needed to be worked with to learn to trust people.  I think when she finally went to her forever home, Goose had come to like her. He looked for her for quite some time after she left.”

Along the way, those cat foster parents who prefer slow introductions have discovered a few ways to smooth the transition. Connie Smith said that her resident cat wasn’t happy at first about having new cats in the house, so she gave her extra love. In addition, Connie shared, “I had long conversations with her about helping the other kitties who didn’t have a home and she adjusted pretty well. There are also products one can use if a cat is unhappy with fosters in the house, like Feliway and rescue remedy.”

For years, Jeanne Kudich used to allow her resident pets and foster cats mingle. Her two boy cats were fine with this setup, and one even helped raise the kittens.  Heather Davies shared, “My two resident 11-year-old males react according to the behavior of the foster cats. If the foster is neutral, my boys are neutral. If the foster is more confident, we can get mild spats. Only occasionally have I had to re-separate post quarantine.” Even so, she did note that if a foster cat decides to sleep on her bed, the resident cats will refuse to sleep there until the foster leaves.


Connie has a room for her foster cats, but the door is left open and they can come and go as they wish, to the degree that they are comfortable venturing into the rest of the house among her resident cats. As for her own cats:” For the most part, since I’ve been doing it their entire lives, my cats ignore the foster room. I have one who brings the foster kittens toys. As my cats grew older, they become less generous with their territory and would hiss at escaping kittens. My toy bringer still continued to sniff them and follow them around.”

Finally, Heather had this to say about allowing foster cats and resident cats to live together: “I help them adjust by treating everyone the same. I’m a high turnover foster home. My boys have realized that eventually the interlopers will leave.”

What about when the fosters pets are cats and the resident pets are dogs—or, as in the following example, vice versa? A quick supervised introduction could be all it takes to determine if the setup will even work. Amy has two very social cats. According to Amy, the cats are quick to check out a new dog by getting right in its face. She remarked that the family knows right away if the foster dog is cat-friendly. Sarah said, “My dog is a bit of a jerk to cats. He’s the gauge for whether or not the foster cats/kittens will be okay with dogs. If they tolerate his type of play and engage, they will be absolutely fine in a home with dogs. If not, they won’t.”

At this point in my article, I’d like to share our family’s personal experiences. My husband and I first ventured into pet foster care in 2014. We started with a senior silky terrier named Gizmo. When the foster coordinator for NE No Kill Canine Rescue brought Gizmo to our home, we introduced him to Barnaby, our toy poodle, and Lucy, our muted calico cat. The reason for immediate introductions was that we didn’t know how long we’d be caring for Gizmo but assumed it would probably be for at least a few months: few people are eager to adopt a senior dog with Cushing’s Disease. Gizmo was very excited to meet Barnaby, but Barnaby was not excited to meet Gizmo. Barnaby likes people, not other animals, despite my husband’s early attempts to socialize him. As for Lucy, Gizmo was not excited to meet her, which we had been told to expect. Terriers are hunters, and cats are tempting prey. We were therefore fortunate that Gizmo was partially blind and deaf and did not pose a significant threat to Lucy, except to her hearing (and ours) due to his frantic barking whenever he detected her presence. We happily welcomed Gizmo into our home and eventually adopted him ourselves, but we were aware that he caused some amount of stress to both Barnaby and Lucy. When Gizmo died, we decided we weren’t ready to take on another dog.

Cats were another matter. We knew that as a community (feral) cat, Bootsie would be a long-term foster, so we followed the protocol with her for slow introductions. It took a year for our resident cat to stop bullying her and to begin somewhat tolerating her. And as we did with Gizmo, we fell in love with her and adopted her ourselves. Then along came Rainy, an adorable and friendly kitten who we expected to be a short-term foster due to her high adoptability. And yet instead of keeping her separated from our cats we threw caution to the wind and introduced her to our cats as soon as we could. And we’re glad we did. Rainy is proof that personality can be the key to whether foster and resident pets get along. Cinder and Bootsie didn’t greet Rainy with open paws, but Rainy didn’t care. She was unflappable in the extreme and was determined to befriend our cats whether they liked it or not. Naturally, we adopted her too. Having at that point adopted every pet we’d fostered, we decided that we weren’t pet foster parent material.


We put a hold on fostering until the fall of 2017, at which time we rescued a potentially feral kitten named Onyx. Although we intended to find Onyx an adoptive family, we couldn’t neglect her need for socialization. Not only did we invite friends over to visit her, but we also introduced her to our resident pets. Barnaby tolerated her, but our cats hissed whenever they saw her. In turn, Onyx wasn’t happy about them either, and would arch her back whenever she saw them. Our cats stopped hanging out with us—especially at night—until Onyx finally found a forever home in February 2018. Even so, I believe that the experience prepared our cats for future foster cats. Since May 2018, Andy and I have fostered kittens through The Cat House, and our cats have learned to ignore their presence in our guest room. Of course, certainly it has been easier for our cats to ignore them, as we’ve never tried to introduce any of the momma cats or the kittens to our cats.

Figuring out the best introduction process for each foster pet has been a matter of trial-and-error for my husband and me. To reiterate what Jayne said, what best suits a pet can depend on the personalities and backgrounds of the pet and the resident pets. In generally, however, it should be clear that slow introductions are generally best.

Soon our current foster kittens will be old enough to be adopted, and will be moved into the local cat shelter. Andy and I will be the ones who will miss them, while at most our pets will notice and appreciate the return of calm and quiet to our house. Overall, this seems to be true of other pet foster homes too, with emotions on behalf of the resident pets ranging from nonchalance to elation. Heather said, “There’s much purring and affection from my cats. If they’ve banished themselves from the bed they immediately come back.” Yet there are those resident pets who have grown used to having fosters around and will search for them after they’re gone. There are even times when friendships have been formed. As for the foster pets themselves, from our experience it seems that there is an adjustment stage. After all, they’ve lost the home in which they’ve grown secure. But pretty quickly the foster home becomes a distant memory as they find love with their forever-home and family.

Special thanks to members of the following groups who answered my questions about fostering: Blog Paws News and Boost Group, Cats with Blogs, Dolly’s Legacy Happy Trails, and Make Lincoln Kind Again.

EDITOR’S NOTE: My husband and I are fostering the three kittens featured at the top. They will be available at The Cat House this summer.

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