Hi - one of my ferrets likes the dogs bones too.  Its not that they are
bad/poison for your ferret so much as they don't provide any nutritional
value.
 
They are way to low in protein and fat.  However they will fill your ferret
up so he doesn't eat his normal food to get his nutrition.  So one of the
little corner nobs broken off is a nice treat but they should not be
allowed to fill up on "junk food".  If you ferret is wildly crazy about
them and also older - You might try switching him to Totally Ferret food
for seniors.
 
My ferret who likes the dog bones seems to dislike all foods that are "too
rich" and gravitated towards things I felt were low in fat and protein for
a ferret.  (Well except heavy cream, they both LOVE heavy cream).  He
seemed happier with the Senior ferret food - I was surprised but I think
it fits the pattern.
 
Mary
 
"Animals are not brethren, they are not underlings; they are other
 nations, caught with ourselves in the net of life and time,"
 Henry Beston
[Posted in FML issue 3274]