Cat muscle tone loss entire body

Question
My 15 yer old female cat (8lbs 12 ounces) has muscle wasting and tone loss but does not lose weight. She eats (4-5 ounces wet food /day) and drinks (never see it) no more than she has ever consumed.  She is becoming very bony (collar bone and spine) and limp (rag doll)feeling and is losing strength as seen when she jumps up to higher surfaces. She passes solid and fluid well and functions normally in every way (very affectionate). Extensive blood testing (9/05 and 2/06) says all organs function within limits. Not tested for free T4/T3 becasu there are no visible or acoustic signs of thyroid problems. Internal organ X-rays all ok. No symptoms of thyroid or heart problems including rates or sounds. Has a lipoma (3/4 golf ball size  under left front armpit.   No internal lumps felt.
New Vet's suggest things that have been ruled out based on above. Need out of the box thinking. She can't last 2 months if she continures to lose skellital muscle at the current rate. I need a solution. What should I do?

Respectfully,
Joe Carey  

Answer
Hello!

It's really hard to tell without seeing her, considering she has every test normal. She has tested also normal for glucose? She may have diabetes. She may have a maldigestive disorder caused by something like exocrine pancreatic insufficiency. Does she have diarrhea at all? Also have they done a fecal test for intestinal parasites? That may cause weight loss too. Hypoadrenocorticism is a possibility (endocrine disorder caused by deficient production of glucocorticoids like cortisol or mineralocorticouids like aldosterone or both). These are all only possibilites of course, since this is a complicated problem. For general muscle loss and to increase appetite, the use of anabolic steroids may help, but of course this is something that your vet needs to decide on. I hope that I could have been of any help, please do not hesitate to contact me if you have further questions.

Kind Regards,
Caglar Kondu Erkip, DVM