If you were to compare your dogs to a traffic light, would you say they are “green light”, “yellow light”, or “red light” dogs? A green light dog is friendly with all dogs and people and has appropriate meeting behaviors. Yellow light dogs are those that are friendly but you should use some caution in managing their interactions. Whereas, red light dogs are very reactive toward other dogs and/or people. This reactivity is usually aggressive looking. However, with some dogs, it is friendly but extreme excitement that but would cause most dogs to attack them due to their out of control, over the top, excited approach.
You probably know which traffic light color your current dogs are as you have observed their interactions with others in many different situations. If a current dog or the new dog would be considered a “red light” dog, you should not introduce them without the assistance of a professional dog trainer. Most aggressive red light dogs will lead happier lives being the only dog in the household and it is not worth the risk of injury to try to introduce them with other dogs in the household. Instead, the goal should be to work with a consultant one to one, so that the red light dog can become a yellow light dog enabling you to walk your dog in public places.
When introducing the new green light or yellow light dog to the household, consider him or her to be a “yellow light” dog before assuming the dog to be a green light dog. The secret to introducing dogs is for the interactions to be frequent and safe. Introduce the new dog to each of the current household dogs individually rather than putting them all together at one time. The first interaction(s) should occur in a neutral area for both dogs.
Every situation and dog is different so it is difficult to prescribe the best way to introduce dogs to each other in every situation and in the context of an article. An experienced dog trainer will help you identify and learn the dogs’ body behavior clues to ensure the interactions are done as safely and effectively as possible. However, in general terms it is recommended to have both dogs on long lines (10’-20’ long) instead of six feet leashes. The long lines allow dogs to do play bows toward each other, go away from each other if desired, and prevents opposition reflex (a dog becomes frustrated by a tight leash and pulls forward into the collar from feeling tension on a leash).
After observing the dogs’ interactions toward each other at a safe distance, allow them to approach each other in an arching circle. If their behaviors continue to be friendly and non-stressed toward each other, allow them to meet. You should remain holding the long lines in case you have to pull the dogs apart but there shouldn’t be any tension in the lines. The next step is to allow them to meet subsequent times in other neutral settings to play with each other, to receive treats with the other dog present (be careful to have the dogs tethered so that they cannot grab the treat from the other dog and teach them to be patient while waiting for their treat), to go for walks together, etc.
If you are unsure if the dogs should be allowed to meet, you might place a muzzle on each dog for their safety. However, unless both dogs have been accustomed to wearing a muzzle gradually over time, placing a muzzle on them simply for this exercise is not likely to be effective as the dogs will probably spend their energy trying to remove the muzzles making it difficult if not impossible to view what their natural reaction would be to a strange dog. Dogs who show fearful and/or aggressive tendencies should always be worked sub-threshold. This means working them at a distance that they are able to tolerate and be successful.
After several neutral interactions with no concerns, you are ready to try it within the household. Bring the household dog outdoors to meet the new dog slightly off the property. With another positive interaction completed, walk the dogs together into the house and continue to supervise their interactions. Do not allow the new dog to enter the house to greet the household dog within, as some dogs become anxious upon seeing another dog come toward them through a narrow entry way such as a doorway, hallway, or out of a crate.
During times you are unable to provide close supervision, you may choose to separate the dogs via a babygate, tethering them in the same room in which you are supervising them, or isolating them to a crate or another room from each other. Until you are sure that they have bonded with each other (which means that they not only enjoy being with each other but also do not fight over resources such as food, toys, resting places, etc.), it is best to provide close supervision or temporary isolation so that aggressive behavior is not rehearsed. Calm behavior and positive experiences should be rehearsed and reinforced constantly.
By following the above dog training tips, one may be able to determine if a new dog can be introduced into a new household of dogs. Go slow with the process and ensure safety for the dogs and people present at all times. If the dogs do not respond well with each other at any point of the process, stop the introduction and consider a different home for the new dog or contact Michael Burkey, a professional dog trainer and behaviorist for assistance.