INTRODUCING A NEW DOG TO YOUR HOME
Introduce your dog(s) to the new dog for the first time on neutral territory, NOT in your home. Have a friend of family member help you walk them together up and down the street in parallel fashion before taking them into the home. This is called "Parallel Walking" and is a great way to safely introduce two dogs that don't know each other. Walk them on either side of the street, humans in between so the dogs are ALWAYS on the outside. As they seem more and more relaxed with each other you can narrow the gap until they are ready for the sniff.
DO NOT EVER HAVE DOGS MEET FACE-TO-FACE, "chicken" style. Allow them the space to arrange themselves so they can meet at arcing angles. If this is not possible, put your dog(s) either outside or block them off in the home so they do not overwhelm the new dog when it first enters. We suggest that you let them greet through an x-pen or strong metal baby gate, with praise and treats to both sides.
If you have multiple dogs only allow one dog to come to the gate at a time. Keeping control of the situation and keeping the excitement level low (watch for relaxed half-mast ears, tails held at or below the line of the back, soft eyes, tail NOT wagging vigorously) is the goal at all times. When excitement escalates (prolonged vocalization, especially if increasing in pitch or volume or standing on hind legs to wrestle) stop play and separate the dogs until they shake off some of the excitement and calm down. Like all mammals, when dogs are in a state of excited arousal they tend to forget manners and rules. This is not a situation you want. When excitement is high it is important to ensure all dogs are at least 2 feet apart and under control. If they are too excited to be trusted to follow commands, secure the dog from the others for it's own safety. Dogs have a personal space zone of about 1 foot and when another dog inadvertently enters that space during excitement, redirected aggression can take place, even among dogs that are otherwise best friends. This is why controlling excitement levels, strong leadership, and ensuring safety zones are very important. Love is NOT enough. Your dogs depend on you to be a good leader, which means being mindful of their excitement levels, space zones, mental states, and taking action as needed so they don't have to.
IMPORTANT: Crate and secure the new dog in it's own room and let them rest and adjust to their new setting for the first day or two. They need time to take in to their new surroundings and decompress from the stressful environment they just left. Potty and return them to their crate. An x-pen around the crate is handy as the new dog can then choose to come out when it feels comfortable. Don't be surprised if new dog needs to sleep a lot initially, especially if they are fresh from a shelter or long-term kennel situation. This is how dogs process through stressful events. Keeping the new dog apart from your own dogs for the first two weeks is ideal and certainly until it has been seen by a vet to ensure many of the usual common minor things dogs can pick up in shelters and kennels--from viruses to worms to fungus--are not passed to your own dogs.
Potty train them in a separate area, if possible, and pick up feces immediately. Do not allow them to share a water bowl with your own dogs and always feed the new dog in it's crate or behind it's gate, and feed after your own dogs.
How soon you can introduce the new dog to playtime with your own dogs depends on how smoothly the introduction went, their mutual energy levels, ages, size, how socialized each dog is and their individual personalities.
Dogs that lack socialization and training will take longer before being ready to introduce to play with your own dogs and need to be taught rules first (behind a gate, where your own dogs can observe the new dog learning but not interfere) just as the new dog can watch you working your own dogs. This helps the new dog to understand its place in your home and rank in the pack and learn self-control as well as boosting your leadership with ALL the dogs. It's worth the extra time to go slow because a bad experience will set the dogs back and then it takes even more time and effort to achieve a successful introduction. Some dogs will just not be able to safely play together or will not have interest in playing together. Always supervise closely to ensure you can stop rough or too-excitable play BEFORE it escalates out of hand.
Crating or otherwise safely securing the dog at night or when leaving the home is a requirement. It will give your dogs a break and also protect your home from accidents and/or destructiveness. At night, the crate can be moved into your bedroom.
Your new dog should never be out of your sight in your home for the first week, minimum, longer for some dogs. Leash the new dog to you if working around the home and you can't contain the dog to an area you can watch. If you can't watch the new dog--secure them, behind a gate or in a crate. REMEMBER: Your dogs were there first. It doesn't hurt a new dog to crate or secure it in a room for short periods when necessary to give your own dogs a break. Always make the crate a pleasurable thing, NOT a punishment. It is a training tool to help ensure the safety of the new dog as well as your own dogs. Crates are not to be used for all-day confinement.
Be very cautious when taking a dog new to your home off of your property. Until the dog has bonded with you it is very likely to bolt at the first opportunity. Some dogs back up when frightened or startled and can slip out of their collars. A properly fitted martingale ("no-slip") collar can help prevent this.
Be cautious when exposing the new dog to children and strangers. Get to know the dog a little first. In most cases, we do not know the dog's history and so we cannot predict how it will react in some situations. Well-meaning strangers will often bend over and try to pet a dog on the head. Please politely discourage this, as it is a threatening movement to the dog.
Ask people to turn sideways and allow the dog to approach them, and to rub the dog's chest rather than place their hands over the dog's head. An alternative is to ask them to crouch, turned sideways, rather than stand, no eye contact. Some people just won't listen and if the dog is tense and uncomfortable with a stranger's approach you need to be prepared to quickly and politely place yourself between the stranger and your dog. This is an act of leadership your dog will expect and find reassuring. Children are often very frightening to dogs of ALL sizes because they move erratically, shout or screech, tend to stare directly into dog's eyes, and want to grab them around the neck to hug them.
Feeding:
Your new dog should always be fed in a crate. New dogs should be fed away from other dogs until you know how they react with food. Be sure dogs do not interfere with each other during feeding, and when you have more than two you need to feed in pack order.
Housetraining:
Potty train the new dog outside on a leash or in a restricted area until it has adjusted to the new surroundings and you feel comfortable that it will come into the home when called.
Don't assume the new dog is house-trained -- changes in homes and families are stressful for the dog and it may "forget" or need some time to adjust to your routine. Praise when new dog does its business outside, don't just let it out and assume it knows what to do. Go with, give the command ("do your business", "go potty", etc.) and as soon as it happens, quietly praise. Best practice is to assume the dog has no training and proceed as if a puppy, with frequent opportunities to go outside: after meals, playtime, upon waking up in the morning and from naps, after excitement. Some dogs just need a refresher to get back on track.
NEVER PUNISH A DOG FOR SOILING INAPPROPRIATELY. This is ALWAYS your own fault, never the dog's fault. Secure the dog and quietly clean it up out of the dog's sight, using a cleaner with enzymes
General Guidelines:
§ Do not reach over the dog's head to pet it a threat. Instead, pet the dog under the chin or on the chest. For the same reason, NEVER lean forward and hover over a dog that does not know you really well or grab it around the neck to hug.
§ If new dog is shy or fearful don't make direct eye contact or stare. Again, the dog may consider this to be a threat or challenge. Use calming signals, such as squatting sideways and yawning, and allow the dog to approach you first to sniff. Allow the dog to press against you to make contact, rather than try to pet it.
§ Do not pick up a new dog that doesn't know you well! This is good way to get nipped, especially by smaller dogs that may have been handled roughly in the past. When you MUST lift a dog, do it slowly and gently and be sure to support under both the forelegs and the hindquarters. It's not comfortable to be suspended by the belly and many females that have had litters find this especially painful.
§ Teach the dog basic manners - “look” "sit", "down", "leave it," "wait" (short pause), "stay" (pausing until you release) "quiet" and how to walk on a leash.
Good manners help the dog become more adoptable! Always use praise and something positive and watch for the dog offering good behaviors and praise them, rather than just noticing what you don't want and scolding for it. Praise is the most powerful tool you have and dogs WANT to please you. Show them clearly what you want, notice and praise when they comply, and learning goes much faster and pleasant for you both.
Aversion, or punishment, methods (no matter how seemingly mild) have the drawback of not showing the dog what you DO want and some dogs simply ignore them.
If the dog pulls, do not walk until they stop and turn to look at you, then thank them and start walking again. If they nip, put them away from you so they don't get attention--don't make it a game.
When puppies are too rough with other dogs they ignore the puppies and don't give them what they want until the puppy behaves correctly. They are patient and you must be, too. Leaders are patient.
§ Stop play when it goes on for more than several minutes, gets too loud, too rough, or it appears one dog is not enjoying the game. The dogs should take turns who gets to win. If this isn't happening, they are not playing, they are challenging pack roles. Remember that the more dogs in the home the more critical handling all the dogs in pack order becomes. DO NOT EXPECT OR ALLOW THE DOGS TO "WORK IT OUT" AMONG THEMSELVES. That is YOUR job! Do not expect older dogs to teach puppies manners--this is YOUR job!
§ High-value items like bones, special toys, should never be left lying around. These should be given to dogs only when they are secured from the foster(s)/new dog and possibly even the personal dogs from each other (depending on your past experience with your own dogs), and removed and put away when playtime is finished before all dogs are allowed to rejoin.
§ Remember that the dog that instigates trouble or is consistently rude is NOT the "alpha dog", as many people assume. The true top dog never starts fights or trouble because they are secure in their knowledge that they are the top dog and have no need to do so. It is the insecure dog that starts trouble with others. Such dogs benefit from down-stay and sit-stays (to build their self-confidence, self-control, and your leadership) and from strict handling in pack order for everything from what order dogs go through doors, get in and out of the car, who gets food and treats in what order and who is allowed to ask and be granted permission to get on furniture (never the lowest dogs until they have demonstrated obedience to house and pack order rules and consistently exhibit good behavior, and never at all if they are fosters). Watch for lower dogs to show deference to higher ones: when the higher dog looks directly at the lower dog, does it turn it's face away, lick it's nose, yawn, and/or blink? Does the lower dog make way for the higher dog? It's important to enforce polite behavior and insist that even when excited, they control themselves (if they cannot step apart and calm themselves on their own at your command, you must separate them yourself) because if you do not assume the role of a leader and enforce these things, your dogs must, and you do not want them to do that. Do not expect or allow your top dog to have to correct misbehaving lower dog--it is YOUR job to watch for misbehavior and redirect and correct as needed.
These tips do not replace professional assistance from a trainer/behaviorist who practices modern, positive-based, fully humane methods.
It is an adjustment period for everyone in the house. Be sure to pay extra attention to Dana to let her know she is loved and not being replaced. This is completely normal. 
