I want to draw blood from a Wistar rat, 4 times in an hour and each time I don't need more than 2 cc of blood. I wanted to use cardiac puncture since I didn't manage to get this amount of blood from other sites. In different sources, cardiac puncture is known as a terminal procedure, meaning that it can be used only one time, because the creature will die after that. But I want to know that can this procedure be done several times under special conditions (e.g. needle size, etc.) and the creature stays alive?