Many people do not give two dogs time to adequately adjust to one another before deciding that having two dogs will simply not work. It can take up to one month for an old dog and new dog to really settle in and accept each other's position in the pack.
Dogs are inherently social animals that live well together in groups, but that does not mean that all dogs get along. Most dogs will welcome a new sibling, but it is not always smooth sailing. The furry family member you have now will face many changes when a new dog enters the picture and may feel a bit displaced.
Introduce on neutral territory.
If the dogs are not showing any negative behaviors, reward them with treats just for seeing each other. For example, when the dog you're walking looks at the other dog, you can say “Good boy!” in a happy, friendly voice and give him a treat. Repeat often.
Sometimes, two dogs cannot live together after fighting. This doesn't necessarily mean you need to rehome them, but it does mean keeping them separated for the rest of their lives. As we discussed above, you'd need to crate and rotate (using either literal crates or rooms) or split your house into two parts.
Most dogs have to “learn” how to get along with each other. If the dog you are considering has not been socialized properly, it might be best to consider another dog with better social skills. The same goes for your own dog.
One person is assigned to each dog involved and approaches that dog from behind. Then grab each dog by the hind legs and lift them so they are balancing on their front legs like a wheelbarrow. Then walk the dogs backwards, away from each other and into separate areas.
Avoid giving too much attention to one pet over another. Train your dog to feel safe and relaxed in their crate. Make a separate feeding space for multiple animals. Don't pet one of your animals to make others jealous purposely.
Start on neutral territory where you have plenty of space, like a park, open field, or quiet street. Start on opposite sides of your space walking the same direction. When one dog looks at the other one, they get a treat. Keep walking until they are no longer focused on each other.
Second Dog Syndrome
As humans, we are bound to forget all of the time and effort it takes to raise a puppy right. All too often, a second dog joins the household and the expectation is that they will behave as the existing dog in the home does, so they are often given the same freedom right off the bat.
After getting a new dog, you may find that they quickly become jealous after you bring them home. Finding a new forever home can be a very emotional time. Sometimes, a newly adopted dog becomes jealous because they crave your attention, touch, and voice as a comfort during this time of change.
Many breeders recommend that your first dog be at least one-to-two-years old before you add a second to the family. If you have an old dog, they may not be physically able to play with or tolerate a pup.
This is when you see one dog trying to engage another dog in play, but the other dog is ignoring that dog by looking away, walking to a different play space or flashing their teeth at the dog. These are all signs that at least one dog doesn't like the other. If you see this behavior, move the dogs away from each other.
Your dog may teach your new dog that anxiety when you leave is “normal” and you will end up with two dogs with separation anxiety. The problem is there's no guarantee a second dog will help your first dog be less anxious when home alone. In fact, in my experience, this is very unlikely.
Many common behavioral concerns, including fear, anxiety, and frustration-related behaviors, become more evident at social maturity and can underly an overly aggressive response. The younger dog may be initiating confrontations to gain access to resources, though that is just one possible trigger.
Some have recommended that the dogs not be anywhere near one another for at least 48 hours following the fight, even if they live in the same household, while others recommend that getting a positive interaction between the two animals as soon as possible is the best course of action -- at the end of the day, however, ...
There are a variety of reasons dogs may show sudden aggression towards each other. Some of the most common causes of conflict between familiar dogs include frustration, illness, and resource guarding. You'll need to clearly identify the root of the problem to restore household harmony.
By nature, dogs are social and thrive in group environments. Therefore, there are many advantages to adopting a second dog, such as: They can keep each other company. Both dogs will be able to entertain each other and get exercise together.
They have conflicting personalities…
However, personality also plays a role. Like humans, dogs' personalities likely change over time. Maybe one dog likes to wrestle, and the other doesn't. Some dogs may be more interested in toys, food, space, attention, or any number of things, while others are wholly unconcerned.
It's better to prevent them than to have to stop them after they occur. People and dogs can become injured when there's a fight. Also, a dog will remember that he's been attacked. It may be very difficult–if not impossible–for them to get along afterwards.
Sometimes the potential risk of injury (physical or emotional) is too great to have them live together. Sometimes the triggers are not easy to control so the safest option is to keep the dogs separated.
The key to success is you
The important thing to remember is that you are in charge and conflict like this is not the end of the world. Break the fight up quickly and calmly, redirect the dog's attention, take them for a walk together, and don't worry that it's going to happen again.