For many people who work long hours, leaving their dog at home alone during the day is a difficult thing to do. And certainly, the dog should have a break by either you coming home and spending time with him, or by hiring a dog walker to do that for you. However, many dog owners feel that is not enough. They believe their solo dog should have a companion. After all, he gets along with other dogs at the dog park and meets other dogs very politely when on leash. Having a canine brother or sister would give him someone to play with all day.
Adopting a second dog to be friends with your current dog can be a great idea...but not always. Some dogs actually prefer to be the ONLY CHILD and although they enjoy playing with other dogs on occasion, resent another dog coming into their home. If this is the case with your pooch, you could have a whole new set of things to worry about. The dogs could fight over food, toys, your attention, etc causing friction between them. This behavior is called "resource guarding" and although it can often be overcome by working with a trainer, it could be an ongoing problem. Also, when selecting the second dog it is not always apparent at the meet and greet if they can really get along long term and compliment each other's personalities. If your dog is really well-behaved and the second dog needs some behavioral tutoring, the assumption may be that your dog will help to teach the new dog the rules. Often it can go the other way, and your well-behaved dog takes on the unruly behaviors of your new family addition. Believe me, I have seen this happen.
Of course, any time you add a new family member, there is going to be an adjustment period and what may appear as a big mistake initially, may work itself out over the next few weeks.
With all the dogs waiting in shelters for a new forever home, I hope many people with solitary dogs do adopt another dog. But be careful, make sure you check out the potential new "furry kid" very carefully. Also, if you have a friend with a dog, you may want to ask if you can have their dog stay with yours for a few days to see how your dog reacts to a second canine in his territory. That may give you some great information to make your decision. Or perhaps, you can foster a dog for a little while and see how your own dog reacts to the "stranger".
The important thing to remember is that taking an the responsibilities of a second dog is a huge undertaking. Make sure you are not doing it just out of guilt cause your pooch is alone while you are away.