I have a ferret that shakes, too, whenever she uses her muscles (not while
resting or sleeping).  Overall, she is healthy otherwise.  She had her tail
bitten off by a dog when young (I don't know the details or age) and only
has an Olive-sized stump left (hence her name "Olive" and she's 4-5 yrs).
I always figured this was the cause, or perhaps something neurological
and/or age related that causes shaking like that illness Katherine Hepburn
has.  I saw another posting so I thought I'd ask while on the subject.
Please send any insights/info.  Thanks!
 
~Lisa  :o3
[Posted in FML issue 2559]