Introduction

Although the abnormalities of the 4th ventricle are highly described using MRI technique in dogs, the normal dimensions are still not well defined.

Objectives

Defining the normal shape and area of the 4th ventricle, establish a new angle in normal canine brains and finding out the effect of head phenotype and body weight on these parameters.

Methods

This work was achieved in the Small Animal Hospital, Glasgow University in 2014. Thirty-two (32) dogs of different breeds were included, had an age range of (1.1–11.1) years and body weight (7–2) kg. The area of the 4th ventricle defined on midline sagittal plane dorsally by the base of the cerebellum, ventrally by the brainstem, anteriorly by the mesencephalic aqueduct, and by the central canal of the spinal cord caudally; its length was defined as the longest line of that area. The area of the cranial cavity was also measured. An angle was defined for the first time and named as the 4th ventricle angle.

Results

The 4th ventricle was divided into three parts: rostral, middle, and caudal parts in which the rostral and caudal parts had a narrow path while, the middle has a wider area. Furthermore, the rostral and caudal parts were characterized by lower signal intensity comparing to the middle part.

Conclusions

Normal shape and dimensions of the 4th ventricle can be well delineated using midline sagittal plane of T2 weighted MRI and the signal intensity of its parts is well demarcated. Finally, the created angle appeared to be in correlation to the head phenotype.