chihuahua housetraining

Question
we have four dogs, greyhound, staffordshire terrer/lakeland cross, jack russell terrier and a six month old chihuahua. The chihuahua is the youngest and was very easy to house train. He fit in fabulously with the other dogs and five cats and is very loyal and affectionate. His behaviour has not altered in the last week,he appears healthy and happy , however, a week ago he climbed on to my husbands lap and urinated.A few days later he did the same to me. I'm at a loss to understand this , I've never experienced it before.He has not had anyother accidents elsewhere in the house. help please

Answer
This is a pack related problem.  Your Chi is making a strong statement and this is not acceptable.  Without the ability to observe him and the other dogs, I can't determine rank in your actual dog pack, but I have the strong feeling that the Chi is beginning to climb the ladder of authority!  If he isn't neutered, do that asap to avoid any testosterone related dominance toward your other dogs and to attempt to maintain pack order (which definitely does exist although you may not be aware of it.)  I suggest you purchase Patricia McConnell Ph.D.'s book on multiple dog households; this will assist you in managing this situation, which might get worse before it gets better.

In terms of the Chi's outrageous marking behavior, and despite his small and adorable stature, this dog does not deserve to be coddled and treated like a baby!  This will only make the matter worse; you need to keep him off the furniture at all times and off your laps, at least in the foreseeable future.  You can put a short, lightweight house leash on him (using a harness, not a collar) and remove him from the furniture, beds, etc. by using the leash and a stern "off" command, until he understands the word "off" and always obeys it.  Concerning your laps, stand up the moment he jumps up and repeat as often as necessary (I doubt more than three repetitions at a time will be necessary) until the dog understands that it is not his place to be there.  Don't anthropomorphize!! and worry that he won't feel loved, etc.  This is absolutely opposite of the way in which dogs receive psychological dominance.  It makes them feel MORE secure.  Your Chi is actually issuing a plea for help with this behavior and you are in a position to do so.