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]