If your male dog is lifting his leg and urinating here and there in your house; on walls, chairs, lamps and alike, this may not be an inappropriate elimination problem. Your dog is most probably presenting territorial marking behavior. Most intact (not altered) male dogs will not mark in the house because they see the home as their den, a place they are secure about. However, if a female comes into heat or another dog perceived as dominant in nature passes through, territorial marking may begin.
Marking can be distinguished from regular urination in that this behavior comprises a small squirt of urine rather than the flow normally released when the dog is genuinely relieving himself. This behavior is largely under the influence of testosterone in unaltered males. Following castration, some 50% of the dogs will cease presenting the marking behavior. However, the further away from the onset of puberty the operation is done, the more likely the behavior has become a habit and will continue even after the hormone level decreases. Even if the dog ceases to mark in your home, he may well continue to do so outdoors or in a veterinarian's waiting room where the scent of other male dogs stimulates the response.
The best preventative measure is to castrate the dog at around six to nine months of age. Cleaning up marked spots is also important so that the dog will not be compelled to over mark that spot. A solution of one part white vinegar to 4 parts water will create a solution that helps to eliminate the odor
In some cases, an insecure dog will occasionally mark in the home, perhaps to strengthen his feeling of security. This can also be a result of separation anxiety. In any case, if the problem can not be resolved, a basic obedience training program taught by a qualified instructor knowledgeable in behavior modification may be useful.
American Foundation for Animal Rescue
http://www.canines.com/library/solutions/marking.shtml