I think that as a new pet owner, we have all experienced this particular situation when with a new puppy or dog. Urinating when excited is a common problem with puppies. If you are also having this issue with your adult dog that is new to the family, there is a common explanation.
After first taking your dog to the vet for a checkup to make sure there are not medical problems; then we know that your dog suffers from submissive/excitement issues. This is very common in puppies and very submissive adult dogs so don't worry, it can be fixed. You will be surprised at how fast we can correct this behavior.
If you dog does not pee when you are in the dominant position like looking in its eyes or greeting it face to face, then it's probably an excitement issue. However if your dog pee's when it's in trouble or when you are bending down to greet him in a dominant position, then of course it is submissive. Luckily, we can fix both of these problems.
Accidents are going to occur so it best to remember that you cannot scold during the training. Just clean it up and continue on with the positive praise when the puppy or dog does go in the correct spot. As with children, dogs and puppies respond better to positive praise over negative discipline.
For excitement peeing, this typically happens with puppies that are less than a year old. With older dogs as well, peeing can occur when friends come to visit or when you arrive home from work. As with the submissive, do not react, just clean it up and praise positively when the dog or puppy pee's in the right place.
Many dogs can have this excitement peeing while playing. It's always best to do the playing out in the yard where it won't matter. Making sure that you are not encouraging rowdy behavior indoors can help you to keep the uncontrollable peeing in check.
When you arrive home, we recommend that you keep your greeting to a minimum. High pitched voices and rowdy behavior can trigger peeing so keep it to a minimum. We do suggest no immediate greeting when you get home as to not encourage the high energy behavior
Hard as it is and tough as it might seem, it will work. So ask your guests to not engage the dog until the excitement has worn off, then they can greet the dog with a quiet, calm hello. Allowing the excitement to wear down before greeting will also discourage the excitable behavior and eliminate the accidental peeing.