Part 1: Specimen Preparation – Head and Hind End Removal

Specimen preparation: REmoval of Head and Hind end

You will now remove the head from your specimen, bag and store it for dissection in the next chapter. You will then separate the hind end of your specimen from the rest of the body with a mid-lumbar transection and then discard the thorax and neck portions as directed in lab. Follow the steps outlined below to complete this specimen preparation process.

1. ALL specimens: Remove the head of your specimen by making a transection with a hand saw through the neck, just caudal to the base of the skull, in the region of C1/C2.
   • Important Dissection Note: Be sure to locate the larynx and thyroid gland prior to making your transection through the neck. Keep the larynx and thyroid gland with the head when you remove it!
2. ALL specimens: Place the now detached/isolated head in a bag, label it with your specimen name, and store it on the appropriate shelf in the cooler.
3. ALL specimens: If needed, remove the abdominal viscera from your specimen (follow the steps outlined below) and discard it. If the abdominal viscera has already been removed from your specimen, you may skip this step of the process.
   • To remove the abdominal viscera, sever the aorta at two points: (1) cranial to the aortic hiatus of the diaphragm and (2) cranial to the terminal bifurcation of the aorta (before the branching to the hind limbs).
   • Sever the caudal vena cava at the same levels as the aorta.
   • Cut the esophagus cranial to the esophageal hiatus of the diaphragm.
   • Complete the transection of the outer edges (costal and sternal parts) of the diaphragm, cutting it away from the ribcage (diaphragm will go with the viscera).
   • Tie off the descending (aka small) colon near the pelvic inlet with two ligatures ~5 cm apart. Cut the small colon in between the two ligatures to protect the visceral mass from fecal contamination.
   • Free the viscera from any dorsal fascial attachments and remove it as a complete unit – this will include the liver, diaphragm, the abdominal aorta & caudal vena cava and both kidneys.
     • • Dissection Note: As this is done, the ureters will be exposed and should be cut midway between the kidneys and the neck of the bladder. The bladder should stay within the body, associated with the pelvis.
4. ALL specimens: Make a mid-lumbar transection with a hand saw to separate the hind end from the rest of the body. Before you start cutting, be sure you are making your cut cranial to the terminal bifurcation of the aorta (before the branching to the hind limbs).
   • Important Dissection Note: Be sure to retain all reproductive tract parts, the deep inguinal ring/inguinal canal region, and identifiable portions (approximately 4-6 inches) of the abdominal wall with the hind end.
5. ALL specimens: The remaining attached right hind limb may be transected mid-tibia, just below the stifle, to facilitate bagging and storage of the specimen.
6. ALL specimens: Discard the thorax and neck sections of the specimen by sawing them into pieces that will fit within the designated discard bags. Place full discard bags into the proper disposal cart.