Jaymi,
 
I too have a VERY fat ferret.  He did a very rapid weight gain in the
spring and it is only getting worse.  My vet is petty baffled.  The one
thing that did work for a while and seems to be holding him steady is a
thyroid drug Thyroxin.  Ferrets VERY rarely have thyroid problems.  So this
was one of the last things we tried.  He retains water also, so for this he
is on lasix, a diuretic.  He is also on 2 different drugs for adrenal and a
heart medication.  His heart became enlarged when he gained so much weight.
It was to much work for the little thing to move him around.
 
A signs of distress because of the weight you should look for is mainly
trouble breathing.  My Elbert is so fat his organs, such as lungs, are
getting squished.  This is most noticeable in his breathing.  Poor guy.
 
As a very very last resort my vet put Elbert on a diet.  He is on low-cal
food.  He was very hesitant to do this because ferrets need the high cal
food to be as active as they are.  Poor Elbert seems hungry all the time.
(so we let him sneak the high cal food)
 
If you have any other questions please email me and I will answer as I can.
It is really sad to see Elbert so fat and uncomfortable.  If your vet comes
up with something that works please let me know.
 
Susan Downey and her frenzy of 5
 
Note on Elbert: When we got him he was less than 1 pound, he was very
malnourished.  We named him Elbert after the tallest mountain in Colorado
in hopes that he would grow that big.  Well he did and some, he is now
toping 4 lbs.  and is not a 'big" ferret just fat.
[Posted in FML issue 2863]