WE have one ferret we rescued, who has (had) rickets, so her body is
rather squat, short, and "fat" (not really fat, but she has a lot of
body to shove into a small set of bones..)
 
anyhow the point is, she often looses hair around her shoulders, armpits,
and knees, mostly simply caused by "rubbing" i.e: her arms ( forelegs)
rub against her chest a lot and the hair falls out where the "rubbing"
happens.  This depends on the season and her regular weight gain/loss.
 
She also sheds her coat "suddenly".  Some ferrets take weeks to shed,
others will shed overnight, and some shed dramatically, to the point
where they look bald in patches ... but then it grows back..  usually
within a week..(not fully, but you should see new hair growth)
 
I would not be too concerned, unless a/ it doesn't grow back soon, or
b/ it starts on the tail ( but that doesn't doesn't sound like your
little girl)
 
although it is fall, they do tend to shed coats before bringing in their
winter coat, although not as dramatically as they do when they shed their
winter coat for a summer one but it does happen.  I am guessing that it
would depend on the climate you have where you live ?
 
The only other thing could suggest is ?  could she be pregnant or having
a false pregnancy ?  female ferrets will shed coats, especially on their
underbelly, when birthing ( or false birthing) is close, they use the
hair for nesting apparently..(or are making "access" easier for the
kits..)
 
just some thoughts ( sorry, I don't claim to be an expert)
 
Darrin
[Posted in FML issue 4656]