Introducing a New Dog
The first meeting should always be on neutral ground and preferably outside.
Walk both dogs parallel to each other and at a distance where they are relaxed. Gradually move the two dogs closer together and if they appear to be comfortable with each other, release them and allow them to meet. Avoid meeting while on lead, as a tense lead may cause problems. If you are worried about the recall of either dog, then allow a long line to trail. Keep the meeting brief and call each dog away after the initial greeting. Treat both dogs and allow them to meet again. Try to keep the meeting controlled and low key. Pay particular attention to the dogs' body language and notice if either dog is becoming tense. If you notice tension building, move the dogs apart to a distance where they are relaxed, and attempt the exercise again.
Once the dogs seem at ease in each others' company, the next stage is to introduce the new dog to his home. Make sure that the resident dog is not in the house when the new dog arrives. The first introduction will be one of scent discovery, so allow the new dog to run around all areas of the house to which he will be allowed access.When he has thoroughly investigated the house, take him into the garden and allow him to explore. The resident dog can then be brought back into the house and should be allowed to investigate the new smells. When everything is relaxed and calm, reintroduce the dogs in the garden and then allow them into the house.
Be aware that crowded areas, corners, confined spaces and doorways may be flashpoints if either dog is apprehensive, so try to keep everything calm and give each dog as much space as you can.
Order and peace is more likely to be maintained if dogs understand that humans make the rules. Teach both dogs to be patient and polite and do not allow them to barge past in doorways or show similar rude behaviour. Both dogs should learn the benefits of waiting their turn and sharing.You can help to teach this by putting each dog on either side of a safety gate and asking them in turn for a simple "sit". Using Rover's name, ask for a sit and then treat him. Request the same from Fluffy and treat her for the same action. Rover will soon realise that when Fluffy is treated and petted, patient waiting will ensure that his turn is only moments away. Until they understand this game, always make sure that they are separated by the gate.
In the early stages, do not leave the dogs unsupervised. If you own safety gates, they can be put to good use as they allow the dogs to sniff and see each other but they can also move away if they wish. They should be on opposite sides of the gate for eating and sleeping. Keep beds and food bowls far apart at first but gradually move them closer together until the two dogs are comfortable to eat and sleep close to each other.
It is sometimes difficult to tell if dogs are playing or fighting. Good signs are bouncing and play bowing or gentle rolling on the floor with each dog taking turns on his back. There may be mouthing and open mouthed 'jousting'. If the excitement starts to escalate and you are worried that play is heading towards a fight, then separate the dogs and allow them a period to calm down. It should be quite clear if one dog is gaining the upper hand and the other is attempting to retreat.
If a fight breaks out, separate the dogs (but only if it is safe to do so)and give them time on their own. Ignore them for a period as you do not want either dog to feel that they have "won" and accomplished anything by their actions.
Both dogs will benefit from control type obedience such as down-stays, and need to understand that polite behaviour is rewarded but pushy dogs always have to wait until last.
It is difficult to tell how long it will be before both dogs are comfortable in each others' company and peace and order can be expected, as it will depend on individual cicumstances and the personalities of both dogs.
Patricia McConnell has written a very good booklet called "Feeling Outnumbered" which contains many helpful suggestions for maintaining peace and order in a multi-dog household. It can be ordered through Canine Concepts and Doodle Trust will benefit if you use this link.