Canine cognitive dysfunction patients have reduced total hippocampal volume compared with aging control dogs: A comparative magnetic resonance imaging study

Background: Hippocampal atrophy is a key pathologic and magnetic resonance imaging (MRI) feature of human Alzheimer's disease (AD). Hippocampal atrophy has not been documented via MRI in canine cognitive dysfunction (CCD), which is considered as the dog model of human AD. Aim: The purpose of this retrospective comparative volumetric MRI study was to compare total hippocampal volumes between successfully aging (control) dogs and dogs diagnosed with CCD. Methods: Mimics (R) software was used to derive total hippocampal volumes and total brain volumes from the MRI studies of 42 aging dogs (>= 9 years): 16 dogs diagnosed with CCD and 26 successfully aging controls. Hippocampal volumes were normalized to total brain volume and these values were compared between groups using Mann-Whitney U tests. Results: Total hippocampal volume normalized to total brain volume was significantly less for CCD patients compared with control dogs (p = 0.04). Conclusion: The results of this study suggest that - similar to human AD - hippocampal atrophy is a pathological feature of CCD. This finding has potential importance for both investigating disease mechanisms related to dementia as well as future hippocampal-targeted therapies.