To Chris Fohl:
 
Others may post on this topic as well. Here's what I know:
Full-grown female ferrets generally weigh 1-3 pounds (let's see, that's
about 0.5 to 1.5 kg); males weigh 3-5 pounds (app. 1.5 to 2.25 kg).  It's
not impossible but unusual for a female to weigh more than 3 pounds, so the
fact that you saw a ferret once that weighed that much is no indication that
your little girl should weigh the same.  Most females I've seen are between
1 and 2 pounds.
 
As far as weight loss and weight gain, I've read postings from vets on this
list stating that ferrets often gain weight in the winter and lose weight in
the summer.  Disease can cause weight loss, too, but it doesn't generally
fluctuate back and forth, unless, of course, the sickness is treated and the
ferret gets better and gains the weight back.
 
I hope that helps.
 
                 Linda
[Posted in FML issue 1596]