Platt SR, Garosi L.
Journal of the American Animal Hospital Association 2003;39:337-342.
Cerebrovascular accidents (CVA) are one of the major causes of disabil- ity among adult humans. Previously considered uncommon, CVA are increasingly recognized in dogs or cats with the advances of neuroimag- ing. A “stroke” is a focal neurological deficit of sudden onset, resulting from a cerebrovascular accident.1 The causes of strokes can be divided into two basic groups: obstruction of the blood vessels, leading to infarc- tion [Table 1]; and rupture of blood vessel walls, leading to hemorrhage [Table 2].2 Most types of CVA that are seen in humans have been docu- mented in dogs;3 however, recovery from cerebrovascular disorders in animals is probably more spectacular than in humans, because animals have a less prominent pyramidal system.4
The central nervous system (CNS) requires a continuous supply of glucose and oxygen to sustain its high expenditure of energy. The trans- portation of these fuel molecules requires sufficient blood flow through a cerebral vasculature with adequate capacity. In the dog, blood supply to the brain arises from the basilar and internal carotid arteries, which join at the base to form the arterial circle of Willis.5 The cerebrum is supplied by three pairs of cerebral arteries arising from this arterial cir- cle, with each one responsible for the perfusion of large but overlapping areas of the cerebrum.5 Any diseases that affect the cerebral blood ves- sels will cause disturbances of the cerebral blood flow (CBF), which in turn can lead to tissue damage. The metabolism of the brain is solely aerobic and without any significant energy reserves. The exceptionally high demand for circulating blood and oxygen is reflected in the dispro- portionately high rate of CBF compared with flow to other parts of the body, comprising 20% of the cardiac output and 15% of oxygen con- sumption when the body is at rest, even though the brain makes up only 2% of the body weight.2