My cat's losing weight, normal thyroid. How fast can levels change?

Weight loss is possible due to increased activity, but 9kg to 4kg is more drastic than I would expect. I would discuss doing bloodwork with your vet. Increased activity and weight loss is common in cats with hyperthyroidism. Weight loss can also be caused by kidney disease and diabetes. All 3 of these conditions can be diagnosed with simple bloodwork (CBC, chemistry, thyroid panel) and urinalysis.

If thyroid levels are in normal range then the most common differential diagnosis is Lymphoma which is a type of cancer, unfortunately it is more difficult to diagnose, an experienced ultrasound specialist vet will be able to confirm or rule it out.

No, it is not normal for her to be losing weight and for you to be able to feel her bones. She could be hyperthyroid so she should be examined by a vet for a thyroid test. It is a common disease in older cats and causes weight loss. Your vet can prescribe a medication to treat, if she has an elevated thyroid level.

It is fairly rare, but ask your veterinarian if your kitty may be suffering from Cushing's disease or liver disease. Also sometimes cats can still be hyperthyroid, even though the thyroid parameters are within normal limits (this is called euthyroid sick). He could also have a tumor. In any case, this needs to be investigated further.

Hello sorry to hear about Norman. The behavioral changes, the weight loss, and unkempt coat are all signs of hyperthyroidism. If you are also seeing a ravenous appetite (hence the hunting) and increased drinking and urination they may also fit with hyperthyroidism. The only way to know is to test his blood and measure the levels of thyroid hormone. In the mean time, ensure he has adequate access to water and food until you are able to take him to your veterinarian. Hope this helps and best of luck!

Weight loss coupled with a normal or increased appetite can be a sign of diabetes or hyperthyroidism, to name a couple of possibilities. I recommend getting Felix seen by your vet as soon as possible for an exam and labwork to determine the reason for his weight loss and get him started on treatment.

A common cause of weight loss in cats is hyperthyroidism. Your vet can run blood work to test his thyroid to determine if he has the condition. Other causes include infections, parasites, liver/kidney disease, endocrine diseases, cancer, etc. Schedule an appointment with your vet for to have a work-up.