What is the primary position used when drawing blood from the cephalic vein?

The primary position used when drawing blood from the cephalic vein is sternal recumbency. This position allows for optimal access to the cephalic vein, which runs along the foreleg of the animal. When the animal is placed in sternal recumbency, it facilitates the blood draw by keeping the vein visible and accessible, while also ensuring that the patient is calm and still, reducing the risk of movement during the procedure.

In this position, the forelimb can be extended, allowing for better access to the vein without the additional strain of keeping the animal upright or in a more stressful stance. Additionally, the natural alignment of the body helps in palpating the vein more easily, making the blood draw process smoother and more efficient.

Choosing other positions, such as lateral recumbency, standing, or sitting, may impede access to the cephalic vein due to increased difficulty in vein visibility, palpation, and the likelihood of the animal moving around, which can complicate the blood draw process. Therefore, using sternal recumbency is the most effective and practical method for drawing blood from this specific vein.