Ok I'm not a professional breeder but I have lost count of the number of
litters my ferrets have raised over the last 30 years.  Tell the vet to
wait and put the kits back in with their mother until she stops feeding
them.  There is no hurry to spay and I would wait until the mother has
had time to recover from feeding.  I leave my kits with the mother until
I find homes for them after 10 weeks.  Some live with the mother for
months.  Mothers will feed until they get fed up with the idea and stop
the kits trying to suckle.
 
Chris.
Wessex Ferret Club  (http://www.wessexferretclub.co.uk)
[Posted in FML issue 4867]