Drawing blood from a rabbit is a commonly performed diagnostic procedure, and it should be done safely and efficiently. The simplest and most convenient site to collect a blood sample is the lateral saphenous vein located in the back leg. This vein is superficial, easy to identify after wetting the fur with alcohol, and allows for rapid collection of large enough samples for testing. Diagnostic laboratories can perform routine CBC and biochemical analyses with sample sizes of 0.5 to 1 ml. A 25-gauge needle on a tuberculin (1 ml) syringe is effective for collection but some may be more comfortable with a 3 ml syringe. Remember that rabbits have a short prothrombin time and whole blood quickly clots at room temperature.
There is no reason to sedate a rabbit for this procedure; as long as it is performed correctly, most will tolerate it well. Restraint involves firmly holding the rabbit on its side and extending the rear leg while simultaneously holding pressure around the stifle to facilitate blood collection. If necessary, the rabbit should be wrapped in a towel “bunny burrito” style. To make the rabbit feel more comfortable, covering the eyes or keeping gentle pressure over the body may help. The venipuncture site should be held with direct pressure for 30 seconds to a minute after the needle is withdrawn.
When the lateral saphenous veins are not accessible for blood collection, other blood collection sites in rabbits include the jugular vein, cephalic vein, and ear veins. When choosing to perform jugular venipuncture, one must determine the individual rabbits tolerance for proper restraint for this method. Otherwise the rabbit should be sedated. The cephalic veins are best reserved for intravenous catheterization and are fragile if the rabbit jerks or pulls the leg back resulting in hematoma formation. The use of ear vessel venipuncture in the pet rabbit remains controversial, as many have used it without complication while others like myself were taught to avoid using it. Thus, it is recommended to only use the ear as a last resort. These vessels are fragile and disruption of blood flow in the ear can potentially lead to thrombosis, ischemia, and necrosis of pinnae.
Blood collection in rabbits should be a routine and safe procedure. Experience and patience are key factors for a successful outcome.
by Anthony Pilny, DVM, DAVBP