Hi, I can help you with your question today.
From your description: weight loss, lethargy, decreased appetite and only eating treats, I'm worried about something more serious such a kidney failure or liver disease.
I recommend starting with a physical exam and some senior blood screening.
Is this treatable?
Often this can be enough to diagnose a condition like this, and then we can begin a treatment plan.
Treatable - yes, curable - often not.
That means we can manage these conditions with diet change and medications, but it is hard to say more than that without a concrete diagnosis.
ok thank you
Renal failure, for example, is a chronic and progressive disease.
You're welcome. Please let me know if you have further questions. I am happy to continue until I provide the service that you seek.