MILO the six-month-old Jack Russell terrier is in critical condition after surviving seven hours of open heart surgery for a severe congenital heart defect on Thursday. The dog is recovering in the University of Cape Town’s animal laboratory, where it is expected to remain on the critical list for at least 24 hours. Medical team leader Dr Johan Brink said it is too early to tell whether the operation was a success. He gave the dog a 50% chance. Milo was referred to UCT’s department of cardiothoracic surgery by the University of Pretoria’s Onderstepoort Veterinary Academic Hospital because it is interested in developing techniques for preventing and treating cardiac disease in animals. Brink said the technique is well developed for children, and he and his colleagues operate on between 30 and 40 children a year, but it is in its infancy with animals. He stressed the operation took place in an animal research laboratory and did not involve facilities meant for human patients.