Why is my senior cat not eating, losing weight, and making clicking sounds?

In an older cat, my first thought would be dental disease. This would be painful for Krinkle, cause him to eat less, and subsequent weight loss. It could also be that he has diabetes, kidney failure, or hyperthyroidism. Having him seen by a vet this week is a good idea. I hope this helps!

The main suspicion would be hyperthyroidism, he is showing all the symptoms, you need to take him to the vet ASAP in order to have a blood test done that should confirm this, then your vet can start him on a treatment for this condition (fully treatable).

This is very concerning and may not related to progressing kidney, thyroid disease or diabetes. An urgent vet check and urine and blood tests is recommended. Do not delay investigation as early treatment is required

These are indeed an unusual set of symptoms, thyroid disease and diabetes would be the first suspects for a cat with increasing appetite and weight loss. A specialist ultrasound scan of the abdomen may be worth while to investigate difficulties with food digestion and absorption or even tumours using up the calories

I believe these very general symptoms are very worrying, i cannot tell you what is the cause as there are many options but i strongly advise that you take him to the vet urgently to have a blood test done and get this checked.

I would recommend the bloodwork if possible. Many of the symptoms your describe could be due to hyperthyroidism which can often be managed with diet or medication. Renal disease diabetes are also concerns. Speak with your vet to determine what they suspect is most likely and find out if it is possible to test for one thing at a time instead of running a full panel at once. The vet will suggest the best options but often if you explain financial constraints we can work with owners. If unable to do the diagnostic testing then euthanasia is a reasonable option to prevent her from suffering. Thanks for using Petco Pet Education Center, formerly Petcoach

Hello, thank you for using Petco Pet Education Center, formerly Petcoach. So sorry your cat is having this issue. I suggest you get him to your vet for a check up and some blood testing. Thyroid disease is very common in older cats as is kidney disease and diabetes. All of these things can cause similar symptoms and all are easily diagnosed with simple blood testing. You need to realize that at 17 years old he is about 85 in human years. At this age, things start to fail and go wrong. You need to find out what is wrong so you know how to best treat him. Some things are very easily treated with daily medications. I don't think this is something you are going to be able treat at home without knowing what the underlying cause is. Hope this helps. Best wishes!