Owning more than one dog is very much like having more than one child. When there is only one dog it knows that your attention is undivided and unchallenged. It feels like it is the only one calling for quality time and will not feel threatened. Many dogs, especially males, tend to mark their territory and will do this in the house, even if trained, when there is another dog around.
If you have had a dog for a long period of time and you are thinking of introducing another one into the family be careful about what dog you choose. If the dog you already own is old and not very active then perhaps getting a very excitable dog is not a good choice because the older one will not be able to interact with the younger one.
However, this is not always the case if a member of the family gives the new addition to the household plenty of attention and plenty of exercise, after-all most puppies just want to play.
Other scenarios include adoption which can be a tricky situation. If a dog feels settles in a home and then gets given to another family it may start to feel very insecure. This can be very delicate especially if it is introduced to a home that already has a dog.
Rivalry, in terms of attention is not uncommon and it is most likely to be the new dog that is most adamant in obtaining it. The old dog will not be too phased by the new one but will need those moments of comfort and reassurance. Be sure to give all the dogs in the house equal attention and equal time, if one is asleep give that time to the other and vice versa.
So remember, having more than one dog can be challenging. Giving both dogs equal attention is vital to the well being of both dogs. Giving one dog more time can result in the other feeling unwanted or jealous. Naturally nervous dogs can get overly excited and will find it hard to control their bladders.
Male dog that feel their territory is being invaded will mark their territory. So, be aware of all these possibilities and hopefully bringing another dog into your life will be as easy and simple as possible.