Developmental change of lateral ventricular volume and ratio in Beagle-type dogs up to 7 months of age.

Eighteen healthy Beagle-type dogs were studied using magnetic resonance (MR) imaging from a few days after birth up to 7 months of age. We evaluated the onset of lateral ventricular expansion, the developmental change of lateral ventricular volume and the ratio of the largest to the smallest lateral ventricular volume. The onset of lateral ventricular expansion was defined as the day that the expansion by cerebrospinal fluid (CSF) was first visible in unilateral or bilateral lateral ventricles on the transverse images at the level of the intraventricular foramen. It was found that the expansion of lateral ventricles were first detectable at 3-4 weeks. Lateral ventricular volume ratio varied most from the onset of lateral ventricular expansion to 75 days of age and stabilized after that, although absolute brain and lateral ventricular volumes continued to increase.