What types of age-related changes occur in the canine brain?
The histopathologic changes associated with aging have been described in a number of studies in dogs. Beta-amyloid protein accumulates in diffuse deposits in the prefrontal cortex, entorhinal cortex, and hippocampus. The deposits are detected first in the prefrontal cortex, and their principal constituent is the β-amyloid 1-42 protein, the insoluble fragment that is thought to be neurotoxic.21 Apoptosis of neurons is also detected and tends to localize to those areas where amyloid accumulation is most prevalent.22 Evidence for progressive accumulation of oxidative damage also exists.23 These changes have been likened to the early changes seen in the brains of patients with Alzheimer’s disease. Unlike Alzheimer’s disease patients, however, dogs do not develop mature amyloid plaques with cores and do not develop neurofibrillary tangles. The cerebral vasculature also shows pathologic changes with age. A shorter fragment of β-amyloid protein, the β-amyloid 1-40 fragment, accumulates in the
