Cynomolgus monkeys (Macaca fascicularis) each weighing between 3.5 and 8 kg are used in this model. These animals have a gyrencephalic brain with similar cortical and subcortical anatomy to humans. They also have been used in permanent and transient middle cerebral artery (MCA) occlusion models [6, 7]. Their vascular anatomy very much resembles that of the human aside from a single pericallosal artery and more efficient collateralization than human neurovasculature. The primates rarely develop stroke or neurological deficits in the case of accidental ICA occlusion on one side. However, among the macaques, the neurovascular anatomy of the M. fascicularis has less collateralization than M. mulatta and might be more appropriate in stroke models where ischemic lesions are required [6]. The study goals and outcome parameters must be carefully taken into account when choosing the appropriate primate species. The clear advantage of using a non-human primate is their ability to deliver neurobehavioral information, including a greater series of tasks and neurological assessments for grade of consciousness, motor control, memory, and learning that mimics human testing.

General anesthesia is induced by the injection of ketamine (10 mg/kg) and xylazine (1 mg/kg) followed by tracheal intubation. Anesthesia is maintained by inhaled isoflurane (0.5–1.0 %). Blood pressure, heart rate, rectal body temperature, and end-tidal CO₂ can be continuously monitored during anesthesia and for the duration of the experiment. Sodium thiopental (25 mg/kg) and cefazolin (500 mg) are injected at the beginning of cranial surgery.

This surgical technique has been slightly modified as described elsewhere [1, 3]. All procedures are performed under general anesthesia and aseptic conditions with the skin of the surgical field shaved. The animals are placed in a supine position with the head extended backwards and held in a slightly lateral position with tapes on a foam head holder. After shaving and the standard antiseptic preparation, the skin is incised in a semicircular fashion and the temporal muscle is dissected from the fronto-temporal bone using monopolar cautery. The fronto-temporal craniectomy is performed using high-speed cutting and diamond drills. After opening the dura mater, the Sylvian fissure is opened under the surgical microscope and the arachnoid is dissected from the proximal 14 mm of the right MCA, distal internal carotid artery, and proximal anterior cerebral artery. Autologous blood is collected from the left femoral artery and allowed to clot for approximately 15 min. Five milliliters of clot is placed around the exposed arteries. The dura is closed in a watertight fashion and the wound is closed. Animals are returned to their cages for monitoring of clinical parameters and neurological deficits. For sham controls, the same procedure is performed without placement of the blood clot. Because the pressure of the blood clot itself may cause some cortical damage or arterial irritation, the placement of fibrin glue or an artificial collagen clot without blood cell components might alternatively be considered.