Canine cognitive disorder (CDS) is a neurodegenerative, progressive, and irreversible disorder of senior dogs, generally over eight years old. CDS is characterized by a decrease in cognitive functions. Clinically significant changes in dog’s behavior and daily routines including disorientation, decrease in social interactions, changes in sleep-wake cycles, loss of household habits, poor communication, increased anxiety, and changes in activity levels with the potential to create significant problems and discomfort in the lifestyle of the owners, deteriorating pet-owner attachment and generally be frustrating for the owner. The definite diagnosis depends on brain biopsies, and there is no confirmed clinical diagnosis method developed, meeting the whole criteria of CDS. The owner assessment using several scales available is the primary tool to rely on, which has a high potential to be subjective. Although it still has many dark sides, CDS is a disease with convenient diagnostic and therapeutic strategies available. Veterinarians need to consider this disease in geriatric patients and cooperate by increasing owner awareness, stopping or at least slowing down the disease in elderly dogs, and making the geriatric period more comfortable for both the dog and the owner. This review aims to introduce current information in the diagnosis and treatment of CDS.