Generally there is no need to withhold food or water from rats before surgery because:

Sometimes it is necessary to withhold food or water from animals before surgery so that regurgitation and other forms of respiratory aspiration of vomitus can be avoided. However, rats are not in this category. This is because rats cannot vomit or even regurgitate. Even under anesthesia, they have no risk for "respiratory aspiration of vomitus".

Explanation:

answer; the confederacy could afford to move a large number of prisoners hundreds of miles but could not afford to fee and house the prisoners;

nasa 3