A review with 7 referencesElderly dogs with cognitive dysfunction provide an excellent spontaneously occurring animal model of age-related cognitive decline (ARCD), dementia, Alzheimer's disease (AD), and other neurodegenerative disorders.Some similarities include: (1) occurrence of clin. relevant behavioral and cognitive problems; (2) common prevalence, which likely increases with age; (3) deterioration of performance on formal cognitive tests with increasing age; (4) Alzheimer's-like pathol., increasing with age; and (5) response to L-deprenyl therapy.The population of pet dogs who exhibit cognitive dysfunction may also offer an addnl. model system for epidemiol. and pathol. studies, development of diagnostics, and the evaluation of cognitive enhancer drugs.