Edna, orange tabby, will be 18 next week. She's the oldest cat we've ever had and we got her at 5 weeks. Our last cat, a Siamese named Sam, made it past 16 when his liver went out. We never even kn...
My last two cats were 17 and 16, but both were diabetic and eventually succumbed to complications related to the disease. Yet, that would still be considered a full life?
I believe that its possible cats can develop their own version of dementia and alzheimer at advanced age. That might not be the reason in your case. Best to pose the question to a professional.