One of my cats, a DSH tux spayed female, has recently lost more than half her weight. I took her to the local vet and found that my cat had hyper-thyroid . She will have to take anti-thyroid from now on. (http://www.medhelp.org/posts/Cats/How-To-Give-Your-Cat-A-Pill-Humorous/show/1364044) The reason I post this is to alert other cat owners to be mindful of sudden weight changes. The vet said I waited far to long ad my cat may now have kidney problems. Remember that we animal lovers are caretakers first.