Alzheimer's disease (AD) and vascular dementia (VaD) are neurodegenerative disorders which majorly affect lives of elderly. Use of animal models to study human diseases is crucial for understanding pathological mechanisms of the disease progression and development of new therapies. Unfortunately, all information obtained from model organisms, especially mice, cannot be directly translated to humans because of irreconcilable differences between them. Existing therapies for neurodegenerative disorders are only symptomatic, but the ultimate goal is to efficiently and safely cure the diseases. Stem cells with their unique properties represent potential for new treatment approaches. In this thesis main characteristics of AD and VaD, the two most frequent neurodegenerative diseases are presented. By literature review we compared animal models available for studying pathophysiology of neurodegenerative disorders and possible treatments with cell therapy. In the practical part of the thesis we examined brains of dogs with canine cognitive dysfunction, a disease similar to Alzheimer’s disease. Congo red dye and immunohistochemistry detected amyloid beta deposits in the cerebral cortices and in the walls of blood vessels. Based on the results we conclude that pathological abnormalities in the canine brain share a high rate of similarity with histopathology of human AD and VaD. Based on all this, the aged dog represents an important animal model for studying neurodegenerative diseases.