Welcome to YT! Glad to have you both here. So sorry to hear about the loss of Gizmo. How generous of your husband to give you Topper. Be sure to sign him up for our Little Gentleman's Club, you can do that on this thread:
http://www.yorkietalk.com/forums/sho...ight=gentleman
While wiping Topper may help with the immediate odor, it sounds like you are concerned about the smell of the urine - which I know nothing about. I'm wondering if that is the smell he has always had or if it's recent, or something you noticed with changing foods? I would consult your vet, if you are afraid it might indicate something is wrong within his system.