Aim of this work was isolation and cultivation of adult stem cells from different sources, mainly from umbilical cord, amnion and bone marrow of the dogs, and at the same, to diagnose and stratificate patients with Canine Cognitive Dysfunction Syndrome (CCDS). Isolation and cultivation of mesenchymal stem cells (MSCs) was performed according to standardized protocols created by us, and healthy dogs served as donors. By choosing suitable sources of MSCs we carefully characterised cells from this sources with all the characteristics of MSCs. Their ability of expansion and differentiation, together with their paracrine and immunomodulary effect, was proved by application of their conditioned media to patients with chronic spinal trauma. Canine Cognitive Dysfunction Syndrome (CCDS) is a disorder with high prevalence, but small diagnostic rate. In this work, we focused on new diagnostic approach, mainly with peripheral and central biomarkers in combination with questionnaires and post mortem changes in the brain. Early diagnostic was proved with identification of neurofilament lifht chain (NFL) with its great role in pathology of the disease. We correlated this information with other clinical and patological changes, so we succesfully diagnosed patients with mild CCDS. These dogs subsequently meet the inclusion criteria for receiving treatment with chosen MSCs, which safety and efficacy was proved by patients with chronic trauma of the spinal cord.