Variations in the Circle of Willis in the New Zealand White Rabbit

Purpose: The New Zealand White rabbit (NZWR) serves an important role as an experimental model for vascular research, specifically in the area of stroke. Here the authors document vascular variations in the circle of Willis (COW). Materials and Methods: Subselective internal carotid digital subtraction angiography was performed in 100 NZWRs. Results: Important variations include hypoplasia in 36%, duplication of the middle cerebral artery in 29%, asymmetries of the posterior region in 19%, and multiple variations in 28%. The complete classical symmetric COW without significant variation is present in fewer than 30% of animals. Conclusions: With recognition of the variations, the NZWR becomes an improved research model.