Unique Clinical Anatomy & Venous Access

Dogs differ anatomically and physiologically in several key areas compared to humans. Knowledge of these differences will assist providers when managing MWDs.

Most MWDs are German Shepherd Dogs, Belgian Malinois and Labrador Retrievers, with a weight of 50 to 80 pounds (23 – 36 kilograms). Dose drugs based on actual body weight whenever possible.

VENOUS BLOOD SAMPLING & IV CATHETERIZATION SITES

Use the cephalic or lateral saphenous vein for routine blood sampling, drug administration, and routine intravenous (IV) fluid therapy. Use the external jugular vein for long-term IV fluid therapy, large volume fluid delivery, and repeated blood sampling.

Cephalic Vein

Figure 1 shows the location of the cephalic vein on the cranial (anterior) forearm. The accessory cephalic vein and cephalic vein join in a Y-shaped configuration distal (toward the carpus or wrist). Figure 2 shows proper technique for occlusion of the cephalic vein. An assistant will occlude the vein by extending the elbow joint and occluding the vein while rolling the vein outward at the elbow. Figure 3 shows proper location of an IV catheter in the cephalic vein.

Figure 1. Cephalic Vein Location.
Figure 2. Occlusion of cephalic vein.
Figure 3. Cephalic IV catheter placement.

Lateral Saphenous Vein

Figure 4 shows the location of the lateral saphenous vein on the lateral aspect of the hind limb at the distal tibial area, coursing caudally and proximally from the hock (ankle) and over the gastrocnemius tendon.

Figure 4. Lateral saphenous vein location.

External Jugular Vein

To access the external jugular vein, standard human central venous catheter kits can be used; the Seldinger technique is most reliable.

The external jugular vein is in the jugular furrow (Figure 5) and is punctured distal to the junction of the proximal tributaries. Clip the hair and perform a sterile preparation (including draping). Create a small skin nick using a #11 scalpel blade or an 18-gauge needle over the intended catheter insertion site to facilitate skin penetration (Figure 6).

A large bore over-the-needle catheter is inserted through the skin and directed caudally into the external jugular vein (Figure 7). The opposite hand can be used to occlude the vein. Following full insertion of the over-the-needle catheter (Figure 8), a Seldinger guide wire is inserted into the hub of the catheter (Figure 9).

The guide wire is advanced about two-thirds of the way, and then the catheter is removed, leaving the guidewire in place (Figure 10). It is essential to maintain control of the guidewire. A single or multi-lumen central venous catheter is advanced over the guidewire (Figure 11). Use of a dilator is often necessary before this step to enlarge the puncture in the skin and vessel to accommodate the catheter diameter.

The catheter is advanced into the external jugular vein (Figure 12). The guidewire should extend from the proximal end of the catheter. Remember to always maintain control of the guidewire. Once the catheter is fully inserted, the guidewire is removed, and an injection port is attached to the catheter hub (Figure 13).

Secure the catheter to the MWD’s skin with suture through the wings of the catheter hub, and circumferentially around the catheter base (Figure 14). The central venous catheter should then be secured on the MWD’s neck with roll gauze or cast padding (Figure 15) followed by non-adherent bandage material (Figure 16). At least two fingers should be able to be placed under the bandage to ensure it is not too tight. Always monitor the MWD for any signs of facial swelling or respiratory distress caused by the bandage being too tight.

Figure 5. Location of external jugular vein with optimal catheter insertion site.
Figure 6. Skin nick to facilitate external jugular vein catheter placement.
Figure 7. Insertion of over-the-needle catheter into the external jugular vein.
Figure 8. Full Insertion of over-the-needle catheter into the external jugular vein.
Figure 9. Insertion of Seldinger guide wire into the external jugular vein.
Figure 10. Advanced Seldinger guide wire caudally into the external jugular vein.
Figure 11. Advancement of central venous catheter over the Seldinger guide wire.
Figure 12. Advancement of central venous catheter into external jugular vein.
Figure 13. Full insertion of central venous catheter into external jugular vein.
Figure 14. Secured central venous catheter to MWD skin.
Figure 15. Securing central venous catheter with roll gauze or cast padding.
Figure 16. Complete securement of central venous catheter with bandage material.