Caution must be taken to avoid puncturing a distended urinary bladder, the bowel, or the liver. The area most frequently used is between the scapulae. Clean the skin with alcohol, clip or part the hair, and fold the skin over the needle rather than thrusting the needle into the skin. If repeated injections are to be made, rotate sites. The hair should be clipped and the skin disinfected.
Adequate restraint is important.
The amount of blood needed and other factors will govern the method and sites of collection. Proper insertion of the needle into a vein or other part of the vascular system is normally the most difficult part of the procedure. Certain guidelines can be given, but only practice provides proficiency. Veins may be expected to roll, collapse, or shift, making entrance difficult. A precise, careful introduction of the needle is best and several attempts may be required.