Chronic inflammatory responses have adverse effects on the memory retaining areas of the brain, such as hippocampus and neocortex. Understanding how inflammation influences hippocampal neurobiology during aging is of significant importance to the study of normal senescence and neurodegenerative diseases, and knowledge of the various factors involved in cognitive impairment may lead to a better understanding of what causes the adverse effects to memory and what treatments could be used to fight memory loss. Microglia are an important line of defense against various brain insults, and as such are a key component of the inflammatory cascade. By examining the brains of cognitively assessed canines, we will determine the inflammatory response in the hippocampus using microglial immunohistochemistry as a marker for immune function. Immunostaining was performed on hippocampal sections of both normal and behaviorally impaired canines. Quantitative analyses will be conducted using unbiased stereological methods (Stereologer, St. Petersburg, FL). We hypothesize that we will observe elevated numbers of activated microglia in the hippocampi of cognitively impaired animals than in the hippocampi of aged, non-impaired canines, and that the observed increases will correlate with behavioral performance. Our results in the canine may provide a more relevant model of natural aging and disease processes in humans than do genetically modified mice, and help elucidate future targets in the inflammatory cascade upon which to focus treatments that may benefit patients with age-related cognitive impairment, Alzheimer’s Disease, and dementias.