This study investigated the different metabolic rates for glucose in different brain regions in awake Beagle dogs of different age groups. They found age-related declines in 15/22 regions. The greatest decreases were between 1 and 6 years of age. Some of these decreases continued with aging in only 5 brain regions.

Regional cerebral metabolic rate for glucose in beagle dogs of different ages.
London, E.D.