elderly cat and rapid weight loss.

Question
QUESTION: I hope you can answer this or point me in the right direction. My cat weighed in at 17-18 lbs in July. Now he is down to under 10 lbs. I have taken him to 3 different vets and have had multiple blood tests and one ultra sound. The final results were normal. He does have hyperthyroid which is being controlled by tapazol and he also has constipation issues being dealt with by using lactulose. He has turned into a bag of bones but he doesn't appear to be in pain or lethargic or unhappy. What is causing his weight loss?

ANSWER: Hi Theresa,

Certainly the hyperthyroid could cause the weight loss but if he's on the right amount of Tapazol it should be controlling it.  Maybe he needs an adjustment of the Tapazol, it can take a while to get the right dosage.  Have the vets said anything about his kidneys?  Kidney failure often goes hand in hand with hyperthyroidism and definitely causes weight loss and loss of muscle mass like you're describing.  Ask the vet if his kidney values were off on his last blood test and if so what can you do about it.  I think vets sometimes don't tell clients when their cats are in the beginning stages of kidney failure, and that's a shame because there's so much you can do to not only prolong your cat's life but be sure its a happy life, too.  My precious black cat, Artifact, lived 3 years with treatment before passing away at the age of 17 years old and she was, as you say, a bag of bones.  My friends teased me that she was a walking skeleton with fur, but she was happy, she wasn't in pain (that's the nice thing about kidney disease, its not painful, just a general wasting away).
Ask the vet, also, if they checked for diabetes since that can cause similar symptoms.
I'm something of an authority on kidney disease, having had several in the past, and two currently being treated who are in excellent condition despite their "numbers."  So ask your vet about this and if it is kidney disease write me back and I'll give you some good tips for helping your kitty.

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QUESTION: He was tested for kidney function and the thyroid problem has been there for a few years now, as well as the constipation issue. All blood tests for kidney, liver, etc function have come up normal. The vets have all been surprised by the results and so far none of them can explain his weight loss other than to say it is because he is old (17).  He also eats pretty normally and drinks normally. Can you think of any other reason he would be losing weight so rapidly?

Answer
Hi Theresa,

Since you've had such thorough testing done of him I really can't think of anything that would be causing his weight loss except, as your vet says, old age.  Cats, and people, tend to lose weight as they get older.  You could try putting some weight back on him by giving him some extra, albeit small, meals during the day, and there are liquid supplements for cats just like for people meant for the older cat who needs more calories. Check out "CatSure", its like "Ensure" for cats and can be found in pet stores and on line.  Other than that I wouldn't worry about the weight loss unless he starts to seem weak or begins to exhibit signs of pain.  You've been very diligent in trying to figure this out, you may just have to accept that he's getting older and this is a natural progression.  Seventeen is quite old for a cat, the equivalent of about eighty in people years!  As long as he's happy and has a good quality of life, that's all that matters.