To Patrick Mulligan re: Perris' weight gain and lethargy.  My late,
wonderful little ferret, Frederick exhibited similar symptoms which,
after many false diagnoses, including a diagnosis of cancer, turned out
to be brought on by congestive heart failure.
 
Fred put on a good deal of extra weight, particularly in the neck area
and towards his rear end, and also exhibited an enlarged spleen.  (Although
the vet noted that it was hard to tell precisely how enlarged the spleen
was, since ferret spleens tend to be so oversized to begin with).
 
My vet put him on Furosemide (sp?) twice a day, via a needless syringe.
Furosemide is a diuretic, and reduced the excessive fluid accumulation in
his lungs, which perked him up a bit.  I compensated for the electrolyte
loss by giving him Pedialyte, which he drank quite eagerly.   (It was
fruit-flavored).
 
I hope this helps you - good luck with Perris!
[Posted in FML issue 1302]