When performing the HD-X or HD-XG surgery in mice, it is important that the animal strain has a complete Circle of Willis. This surgery involves ligating the left common carotid artery and a complete Circle of Willis is critical to enable the right carotid artery to provide the blood supply to the entire brain.
Certain mouse strains or models may have a higher proportion of individuals without a complete Circle of Willis. Indications of an incomplete Circle of Willis include neurologic abnormalities such as a head tilt, circling in one direction, or seizures after surgery.
To ensure that each new animal model to be used has a complete Circle of Willis, ligate the left carotid artery in a pilot animal, allow the animal to recover and verify that the animal does not show any abnormalities, such as those listed above.