I can only relay personal experience, but if you intend to use your boy for
breeding or just let him be a pampered pet, you may want to wait awhile to
see if he drops.  It is entirely possible that this could wait to happen
until he is around a year old.  One of my ferrets held onto his for just
over a year.  At nine months I followed the vets advice, got him neutered
(they also couldn't find the other w/ minimal exploratory surgery) He and
his cagemate rebounded from the ordeal in no time.  4 months later he began
putting on a lot of weight and acting more aggressive towards his cagemate
(not to mention he was applying the odour de' ferret a little too heavy)
Well, too my surprize he had dropped his other testicle after I had been
told he wouldn't.  This meant that surgery #2 was now necessary.  So, the
moral of the story is to never underestimate a ferret's will to do what
you least expect.
 
-Stacie
Loki, VooDoo, and Pica
[Posted in FML issue 2956]