Soon after qualifying as a doctor, Barnard performed experiments on dogs while investigating intestinal atresia, a birth defect which allows life-threatening gaps to develop in the intestines. He followed a medical hunch that this was caused by inadequate blood flow to the fetus. After nine months and forty-three attempts, Barnard was able to reproduce this condition in a fetus puppy by tying off some of the blood supply to a puppy's intestines and then placing the animal back in the womb, after which it was born some two weeks later, with the condition of intestinal atresia. He was also able to cure the condition by removing the piece of intestine with inadequate blood supply. The mistake of previous surgeons had been attempting to reconnect ends of intestine which themselves still had inadequate blood supply. To be successful, it was typically necessary to remove between 15 and 20 centimeters of intestine (6 to 8 inches). Jannie Louw used this innovation in a clinical setting, and Barnard's method saved the lives of ten babies in Cape Town. This technique was also adapted by surgeons in Britain and the US. In addition, Barnard analyzed 259 cases of tubercular meningitis.