Cognitive dysfunction syndrome (CDS) is a disorder resulting in cognitive deficits in cats. Its diagnosis in elderly cats (i.e., 11+ years) is especially complicated because behavioral signs pertaining to CDS are understudied and are often overlooked or interpreted as part of the normal aging process. We aim to develop a checklist to discriminate between behavioral changes in elderly cats related to normal aging-induced cognitive decline versus abnormal cognitive decline (i.e., CDS). The goal is not to use the checklist for clinical diagnosis, but rather to provide cat owners and veterinarians a tool to proactively identify potential behavioral signs of pathological cognitive decline in elderly cats. The study consists of two phases; prototype checklist development (phase I) and examination of the prototype checklist in both clinically healthy elderly cats and elderly cats diagnosed with at least one of the following chronic diseases: osteoarthritis, chronic kidney disease, hyperthyroidism, and diabetes mellitus (phase II). Through this project, we expect to develop a novel checklist specifically designed to detect early or subtle behavioral signs of abnormal cognitive decline in elderly cats. This study will also lead to increased awareness of CDS among cat owners and veterinarians.