Penguins may prove problematic to venipuncture. The peripheral veins are either hidden by dense feathers (jugular and brachial veins) or may have low volume, especially in cold weather (brachial and metatarsal veins). However, all three vessels are readily accessible if attention to anatomy, physiology, and penguin positioning are taken into account. Venipuncture may be achieved using a low volume syringe or a low volume vacutainer. These techniques have been used to sample Rockhopper penguins (Eudyptes crestatus moseleyi), King penguins (Aptenodytes patagonicus), Gentoo penguins (Pygoscelis papua papua), Macaroni penguins (Eudyptes chrysolophus), and African penguins (Spheniscus demersus).
Jugular Vein Sampling
One handler may perform restraint for access to the jugular with the penguin held vertically upright in the arms and the head held in extension and curved slightly away from the phlebotomist. Pressure is applied to the area of the thoracic inlet. The occluded jugular vein may be palpated in the line from the lateral neck to the angle of the jaw.
Brachial Vein Sampling
Access to the brachial vein is achieved with the penguin restrained in dorsal recumbency and the wing held in extension. Applying pressure around the wing proximal to the elbow occludes the vein. The vein is visible or palpated crossing the elbow joint.
Metatarsal Vein Sampling
The metatarsal vein is accessed medially just above the medial claw. The bird is held in ventral recumbency within a horizontal plane in the arms of the handler. The phlebotomist extends the ventral leg for access to the medial aspect. Applying circumferential pressure to the limb just distal to the stifle joint occludes the vein.
Pros and Cons of Different Veins for Blood Sampling
A large volume is readily collected from the jugular vein, although correct positioning and knowledge of topographic anatomy is essential to achieve successful venipuncture. Smaller volumes of blood can be collected more slowly from the other venipuncture sites, although these vessels are more readily identified. The feet are often soiled, especially if the penguins have access to soil, and adequate preparation of the metatarsal vein site can be time consuming. Hematoma formation is a common sequel to brachial vein venipuncture, although hematoma associated with jugular vein sampling cannot be readily assessed in the live bird.