How to safely introduce dogs to one another. Proper dog-to-dog introductions are key to safely adding a new dog to your home, and ensuring all canine family members will coexist peacefully.

[Updated December 18, 2018]

DOG INTRODUCTION OVERVIEW

1. Evaluate your own dogs and make wise choices about new canine family members.

2. Plan your introductions – time, place, and process – to optimize your potential for success in adding a new dog to your existing pack.

3. Enlist the aid of a professional behavior consultant, or knowledgeable friend, to help handle dogs during introductions and ensure the safety of all participants.

You’re contemplating the addition of another canine family member to your pack. You’ve thought it through and are convinced that it’s the right time. Perhaps you have your eye on a homeless dog at your local shelter or a rescue dog staying temporarily in a foster home. Maybe the long-awaited puppy from that carefully researched breeder is due soon, or a friend or family member has asked you to take in a dog that they must rehome. However you plan to acquire your new canine companion, if you already have dogs in your home, you’ll need to prepare for the potentially stressful process known as “new dog introduction.”

Such was the case for us recently when my husband Paul, director of the Humane Society of Washington County, Maryland, warned me that he was falling for Missy, an eight-year-old red merle Australian Shepherd who had been surrendered by her owner to the shelter. Even before our decision to bring her home was final, knowing the importance of dog-dog introductions, I began planning the introduction process.

There are a number of factors to keep in mind that can increase the likelihood of a positive outcome when introducing a new dog into your home. A peaceful first introduction sets the stage for long term relationships. The more heavily you can weigh the odds in your favor for that first encounter, the greater your chance for lifelong peace in the pack. The factors to keep in mind include:

• Timing

• Location

• Number of skilled handlers available

• Knowing and understanding – to the greatest extent possible – the personalities and histories of all the dogs involved

With four dogs already in our family, including Dubhy, our dog-reactive Scottish Terrier, new-dog introductions aren’t simple. Fortunately, we’ve done it enough to know where the high-risk danger zones are with our pack, how best to avoid or overcome them, and how to make optimum use of the above factors.

Timing of Dog Introductions Matter

It’s best to add a new dog to your home when things are otherwise calm and reasonably stress-free. Allow ample time for a leisurely introduction process and a low-key adjustment period with adequate supervision. You’ll also need time to be able to iron out any wrinkles that may appear. This may mean taking time off work, in case your dogs don’t hit it off instantly. Holidays are generally not the ideal time for introductions unless, for you, “home for the holidays,” means lots of quiet time spent alone with your fur-family.

Of course, you can’t always control the timing. Many breeders and adopters have a fairly inflexible preconceived idea of the appropriate age at which a puppy should be transferred to his forever home. A friend or family member may be under personal pressures – landlord dictums, relationship issues, risks to children in the home, or municipal limit laws or breed bans – that require prompt rehoming.

Introducing Missy

A shelter or rescue dog may be facing a ticking clock that dictates a speedy adoption. An outbreak of parvovirus at Paul’s shelter meant that Missy had to come home posthaste, to avoid her exposure to the very contagious disease.

The timing could have been better. I was two days away from hosting a Reactive Rover Camp at my home. This meant that it would be out of the question to temporarily keep the barking Aussie in a stall in the barn – where my training center is located – in order to facilitate slow introductions over a several day period with Paul in attendance. I knew Missy’s barking would render the training environment too stressful for reactive dogs to stay sub-threshold and respond well to our counter-conditioning and desensitization program. We had to get the job done quickly, in order to transition the new girl into our family and our house.

The Best Place to Introduce Dogs

It’s best to introduce dogs in neutral territory – ideally outdoors, in a large, open, safely fenced space. The more trapped a dog feels, the more her stress will push her toward defensive aggression. Plus, when you do introductions in one dog’s territory, it gives him the home-field advantage, and you risk displays of territorial aggression.

Optimum options include a fenced yard other than your own, an off-leash dog park at low-use time (as in no other dogs present), a tennis court (caution – many tennis courts understandably prohibit dogs), or a large, open, uncluttered indoor area such as someone’s unfinished basement.

Our only large, fenced, outdoor open space is our backyard, to which our dogs had, naturally, already staked a territorial claim. Our next best choice for introductions was the training center – a 20′ x 80′ space with very little furniture. We opted for that space for Missy to meet three of our dogs, and the backyard for the fourth.

Number of Skilled Dog Handlers

Ideally, you’ll want one handler per dog. One skilled handler, that is. Someone who panics and intervenes unnecessarily can botch the whole job by adding stress to dogs who are still sorting out relationships.

Barring skilled handlers, at least find handlers who are good at following instructions and don’t succumb easily to hysterical behavior. If you can’t find those, you’re better off with fewer handlers, although you should have at least one other person present, if for no other reason then to help you if the situation gets out of hand.

Life is rarely ideal. Because of our truncated time frame for introductions with Missy, our options for multiple handlers were limited. Paul had to work, my other trainers weren’t available, so it was up to me and my full-time associate, Shirley, to play referee for our pack introductions. I was only really worried about Dubhy’s reaction to Missy; it’s difficult to predict how he’ll respond to a new dog, but we have added two canines to our family successfully since the emergence of his dog reactive/aggressive behavior, so my hopes were high.

Each Dog’s Personality and History

You may not know much about the newcomer, especially if she’s a rescue or shelter dog. You should, however, have a pretty good sense of your own dogs’ canine social skills. Do they play well with others at the dog park? During playtime at good manners class? With their own packmates? How do they act with doggie visitors to their home? During chance encounters with other canines on the streets?

If you have reason to believe that your dogs are anything less than gregarious with conspecifics (others of their own species) due to a history of aggressive behavior with other dogs, or if you just aren’t confident about refereeing the introductions yourself, you might do well to engage the services of a qualified behavior professional. She will be able to help you read and understand your dogs’ body language, and optimize the potential for success. (For more information about translating canine body language, see “Understanding How Your Dog Communicates“, and “Properly Interpreting Your Dog’s Body Language“.

I hope you’ve already given great consideration to good personality matches when you selected your new dog. If you have a dog in your pack who likes to assert himself, you’re wise to choose a new dog who’s happy to maintain a lower profile in the hierarchy. If your current dog is a shrinking violet, she’ll be happiest with a new companion who doesn’t bully her mercilessly. If you have one of those canine gems who gets along with everyone, then you have more adoption options.

If you want your gem to be able to be “top dog,” then look for a soft, appeasing-type dog. If you don’t care where your easygoing dog ends up in the new hierarchy, then you have the entire canine personality continuum to choose from.

We knew our personal canine characters would present some challenges. A quick analysis revealed the following about the dogs we wanted to mingle with Missy:

Fifteen-year-old Katie, a very geriatric, arthritic, spayed, 45-pound Australian Kelpie, with a long history of asserting herself with the other members of the Miller pack. Literally on her last legs, Katie was approaching the last few weeks of her life, and had difficulty getting around. Her crankiness was exacerbated by her physical problems, but her mobility was so limited that she presented a low-level threat.

Seven-year-old Dubhy, an assertive, neutered, 25-pound Scottish Terrier, the loner of the group. He gets along well with the rest of the pack, but rarely engages in play with them. His reactivity developed when he was about 18 months old. I’ve worked with him to reduce his reactivity threshold distance to about three feet, although he’s better with small dogs.

Three-year-old Lucy, a lively, assertive, spayed, 35-pound Cardigan Welsh Corgi, who is the only one of the group who challenges Katie (regularly). She tends to act submissive when meeting a new dog, but guards certain places, objects, and me.

Two-year-old Bonnie, a soft, appeasing, spayed, 35-pound Scottie/Corgi mix who gets along with absolutely everyone.

Eight-year-old Missy, an appeasing, 40-pound female Australian Shepherd, possibly intact (not spayed), mild to moderate lameness in her right hind leg/hip. Missy had lived with other dogs before and has had at least four prior homes.

The Dog-Dog Introduction Process

I prefer introducing a new dog to the easier dogs first, one at a time. Assuming all goes well with the one-on-ones, I try a threesome, adding an additional dog as their behavior allows.

The process I use and recommend to clients is to start with dogs on leashes on opposite sides of an enclosed space. Try to keep leashes loose, if possible. Watch the dogs’ behavior. They should seem interested in each other, alert without excessive arousal. Ideally you’ll see tails wagging at half-mast; soft, wriggling body postures; play bows; ears back; squinty eyes; no direct eye contact. These are clear expressions of non-aggressive social invitation.

Warning signs include stiffness in the body; standing tall; ears pricked hard forward; growling; hard direct eye contact; stiffly raised, fast-wagging tails; lunging on the leash; and aggressive barking.

If you see social behavior, proceed with an approach until the dogs are about 10 feet apart. If they continue to show unambiguous signs of friendliness, drop the leashes and let them meet. I prefer to let dogs meet and greet off-leash; leashes tend to interfere with the dogs’ ability to greet normally, and can actually induce dogs to give false body language signals.

For example, a tight leash can stiffen and raise a dog’s front end, causing her to look more tense and provocative than she means to be, which in turn can cause the other dog to react on the offensive. A defensive dog who wants to retreat may feel trapped because of the leash and act aggressively because she can’t move away.

Initially, leave the leashes on, dragging freely on the floor, so you can grab them and separate the dogs easily if necessary. Monitor the greeting. You are likely to see some normal jockeying for position and some tension, as they sniff and circle, and then erupt into play. As soon as you can tell that they’re getting along, remove leashes and let them play unencumbered. Watch them! You want to ensure that the play doesn’t escalate into excessive arousal (which can lead to aggression), but remember that it’s normal and acceptable for dogs to growl and bite each other in play. As long as both dogs are enjoying the action, it’s a good thing.

If you see warning signs as you approach with the dogs on leash, you’ll need to proceed more slowly. Most commonly you’ll see behavior ranging somewhere between completely relaxed and friendly and outright aggressive. You’ll need to judge whether the intensity of the behavior is high enough that you need to stop and seek professional assistance, or low enough that you can proceed with caution.

If you do decide to proceed, interrupt any of the dogs’ prolonged, hard eye contact by having the handlers divert their dog’s attention with bits of tasty treats. Continue to work with the dogs in the others’ presence, watching for signs of decreasing arousal. Keeping the dogs as far apart as possible in the enclosed area, walk them around on loose leashes, gradually bringing them closer together until they are walking parallel to each other.

Get a list of even more tips on the best way to introduce dogs here.

Stay Calm!

It’s important that you stay calm and relaxed during this process. If you jerk or tighten the leash or yell at the dogs, you’ll add stress to the situation and make it more difficult for them to relax.

Say you see signs that the dogs have relaxed with each other; this is where your experience and instincts come into play. You may decide to proceed with dropped-leash greetings. Or you may choose to end the introduction for the time being. It’s better to err on the side of caution, and do several more on-leash sessions to make sure the dogs are comfortable with each other. Meanwhile, you’ll need to manage the dogs so they don’t have free access to each other. If you’re not confident in your judgment about body language, you may choose to enlist the help of a professional at this point in the process.

If tensions between the dogs escalate or maintain at the same level of intensity despite your on-leash work over several sessions, the wise choice may be to look for a different dog to adopt into your home. Alternatively, you may want to do ongoing work with a behavior professional to try to make the relationship work, knowing that management may be a large part of your life for the foreseeable future.

Be careful if you see no interaction between the two dogs you’re introducing. What appears to be calm acceptance of each other may in fact be avoidance, where neither dog is comfortable with the other and they deal with it by not dealing with it. The problem with this is that sooner or later the dogs will interact if they’re both living in your home, and the discomfort may well develop into aggression. I really want to see some interaction between dogs in order to make a decision about adoption.

I chose to introduce Lucy and Missy first. Shirley held Lucy on-leash at one end of the training center, while I entered with Missy on-leash at the other end. Both dogs appeared relaxed and interested in each other. We approached to a distance of 10 feet and dropped leashes. The two dogs sniffed and circled, with Lucy offering appeasement behaviors: ears back, lowered body posture, corners of mouth slightly pulled back, and squinty eyes.

After a moment we removed the leashes, and the two engaged in some half-hearted play. Then Lucy walked over to the rack that holds dog toys, asking for me to throw her ball. I complied, and she happily chased the ball while Missy stayed at my feet. When Lucy raced back with the ball, Missy growled at her. Note to self: Missy has been here less than 24 hours and she’s already resource-guarding me. This could be problematic, especially since Lucy also displays owner-guarding and space-guarding behaviors. Hmmm.

Missy continued to display occasional mild guarding behavior while Lucy played. Her behavior didn’t escalate and Lucy didn’t take offense. I decided to table my concerns for the time being and proceed with the next introduction.

Bonnie was next. I was pretty unconcerned about this introduction; Bonnie gets along with everyone. My lack of concern was justified. We quickly proceeded to off-leash play, and Bonnie’s very appeasing attitude elicited no owner-guarding response whatsoever from Missy.

I then reintroduced Lucy to the pair, and all went reasonably well. Missy seemed less concerned with Lucy’s proximity to me with Bonnie in the mix, perhaps because her attention was divided.

We decided that Missy had probably had enough for one day, and put off the introductions to the two more difficult Miller dogs to the next day. The start of Reactive Rover Camp the day after that loomed large on the horizon. We had to get Missy out of the barn and into the house!

Missy’s introduction to Dubhy was my greatest concern. I proceeded with caution, and my fears were quickly justified. When I entered the training center with Dubhy, I had a pressurized can of citronella spray (Direct Stop/Spray Shield) in my pocket, high value treats in one hand, Dubhy’s leash in the other. As soon as he spotted Missy at the far end of the training center, Dubhy “turned on.” His head and tail went up, and his normally soft mouth got hard – I could feel his teeth on my fingers as he took treats from me. Happily, he remembered his “Reactive Rover” lessons, and quickly looked from Missy to me for the treats, but there was still tension in his body and arousal in his brain.

Shirley and I walked the two dogs around the training center, gradually bringing the dogs closer together. Dubhy’s mouth softened and his tail lowered as he grew accustomed to Missy’s presence. We eventually brought the dogs within three feet of each other, and Dubhy continued to be reasonably relaxed. I could see that he was still somewhat on alert, but I decided to make the leap, and told Shirley to drop Missy’s leash. Shirley looked at me as if I was nuts, but dropped the leash as requested. I dropped Dubhy’s, and he immediately lunged at Missy’s face with a ferocious snarl.

My heart sank as I leaped forward and sprayed Dubhy with a long blast of citronella to halt his attack. Missy had turned her face away from her attacker, and the spray shoots a very direct, narrow stream, so I could avoid punishing Missy for Dubhy’s aggression.

This was a deal breaker; I wasn’t willing to live with a lifetime of management between these two. If I hadn’t been on a tight schedule for integrating Missy into the household, I would have separated them with their leashes instead of using the spray, and reverted to a gradual introduction process. In fact, I wouldn’t even have gotten so close, given Dubhy’s tension and past history of dog-related aggression. I knew I was pushing the agenda already, by bringing them together quickly.

Dubhy stopped in his tracks and gave me a surprised look. The tension immediately vanished from his body and he glanced at Missy, then looked back at me. He stepped forward and sniffed Missy. She avoided eye contact by turning her head away, then stepped away from him.

Her response to him was so appropriate, and his changed body language so remarkable, that I stifled my first impulse to stop the introduction, and let them continue. Good thing! The interaction proceeded without any more aggression, and Dubhy has been perfect with Missy ever since; go figure! I don’t recommend using an aversive to try to make dog-dog relationships work. Any time an aversive is used there is a significant risk of increasing the negative association with the other dog: Dubhy could have been angrier with Missy if he perceived her as the cause of the spray. I was lucky that it had the opposite effect in this case.

My intent in using the spray with Dubhy was simply to interrupt the aggression to protect Missy. I fully expected that his behavior would preclude our adopting Missy into our home. I was surprised and grateful that it served to modify his behavior, apparently permanently – a happy accidental outcome of my crisis intervention.

As expected, Missy’s introduction to Katie in our backyard was uneventful, due to Katie’s mobility challenges. The aged Kelpie snarked at Missy briefly as the Aussie passed her on the back porch, but Missy, bless her, just ignored Katie’s rude behavior and headed out to the yard to play in the grass. One by one I released the other dogs to join Missy in the yard, all without incident. Missy was home.

Now, a few months later, Missy is doing well. She no longer has to deal with Katie, who passed away a few weeks after Missy’s arrival. Missy and Lucy occasionally posture over favored spaces in the house, but these incidents are minor and manageable. We’ve not had a whisper of inappropriate behavior from Dubhy toward Missy since his citronella experience – in fact, the two of them occasionally play together. Bonnie, as always, is no trouble at all. I hope all of your new family introductions go as well as ours did.

Pat Miller, CBCC-KA, CPDT-KA, is Whole Dog Journal’s Training Editor. Miller lives in Hagerstown, Maryland, site of her Peaceable Paws training center. Pat is also the author of The Power of Positive Dog Training and Positive Perspectives: Love Your Dog, Train Your Dog.