Hang the bag on a hanger with the hook bent so that it is perpendicular to the rest of the hanger. Then remove the plastic cap from the needle and holding the hub of the needle insert it into the scruff. Are You Pulling Your Hair Out Or Stressing Over Administering Subq Fluids Been There Here Are Our Tips On How To Give Crazy Cats Pet Medications Calming Cat Thats not really necessary. . You can use an 18-20 gauge needle on your cat. Position the wire hanger on the top of a door or shelf with the numbers on the bag facing you. Subcutaneous fluids are fluids given under the skin to help provide additional hydration to an animal. A veterinarian can give you a prescription as well as hands-on training. With the 18 gauge which is larger your fluid therapy will go more quickly. For cats it is most common to use 500ml bags for subcutaneous administration. The fluid is slowly absorbed by the body and plays an imp...