I recently took home a male german shepherd from a rescue group. He's about four years old, fixed, and for the most part, well behaved. My question is about his level of excitement/arousal... more often than not, the dog has an erection. Occasionally, he will pee a little. I'm not sure if this is normal and can't really get a good answer as to why. I was thinking at first he was very excited at new surroundings, but it's been about four months now. Could it be a bladder/genital issue? Either way, it makes guests uncomfortable and pet messes are never fun. Thanks in advance to anyone who can shed some light on this.

Some dogs are much more prone to that than others. I am not sure the urination is from of dominance or submission. Good leadership on your part will help in either case. Start with obedience training. The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at Raising Your Dog with the Monks of New Skete (http://www.dogsbestfriend.com/) As you praise the dog for following your commands, it will build its confidence. You want a confident dog, but one that accepts his proper place. Here are some more things to help with the essential relationship you must have with him, Establishing and Keeping Alpha Position (http://www.dogbreedinfo.com./topdogrules.htm) It is kind of like children, they can be more confident if they have loving parents giving them guidance to cope with the world.

Play tug of war with the dog and lose. However at the end of the game, take the rope or toy and put it up, less the dog becomes confused about who is top dog.

Ropes from the pets' store quickly turn to hazardous shreds. Ones I made
Lasted much better. Go to a hardware or home center that sells rope by the
Foot. Buy 2' of 3/4" poly rope. Melt the ends, and tie knots in it. Get
Them as tight as possible, put it in a vise and pound it with a hammer. Watch
Carefully, and be ready to discard when it comes apart.

Finally, make sure it has a den to live in. If you are not using a crate, buy one. The dog may be happier in its den than loose in the house. It relaxes, it feels safe in its den. It rests, the body slows down reducing the need for water and relieving its self. Dogs that have been crated all along do very well. Many of them will rest in their crates even when the door is open. I think the plastic ones give the dog more of a safe, enclosed den feeling. Metal ones can be put in a corner or covered with something the dog can't pull in and chew. Select a crate just big enough for the full grown dog to stretch out in.

A dog that has not been crated since it was little, may take some work.
Start just putting its toys and treats in the crate. Praise it for going
in. Feed it in the crate. This is also an easy way to maintain order at
Feeding time for more than one dog.

Have you talked to the rescue group about the problems? One of the advantages of a good rescue is that they do more to help make sure the placement works.

I doubt it is a medical problem, but it never hurts to discuss any problem with the vet.

I had a similar problem in my belgian shepherd/husky mix. It turned out to be a tiny piece of weed had been caught between the fur sheath and penis, enough to have resulted in what you describe but with a small amount of clear seepage that was not urine. It cleared up when the vet removed it but it so happens that he was an easily and frequently aroused dog (even fixed as he was) and the vet said that may have helped to contribute to his "collecting" a piece of weed. Just a thought.