Post mortem examination of the skull

Removal of Head 

Procedure

  • To gain access to the brain in the head we need to remove the head.

  • It requires the disarticulation of the atlantooccipital joint.
  • Locate atlanto-occipital joint by turning the head up and down.
  • Cut the soft tissue ventral to the joint. Continue the dissection until the exposure of the ventral spinal canal.
  • Turn the head up & down again to identify the exact location of the atlantooccipital joint.
  • Enter the knife between the atlas & occipital condyles and cut the attachments. 
  • Extend the cut laterally along both sides of the adjacent tissues.
  • Continue the cut until the head is fully detached. 

Removal of Retro-Pharyngeal Lymph Nodes 

Procedure
  •  Medial & ventral to the occipital condyles,retro-pharyngeal lymph nodes are present which are a good source for microbiology testing. Remove the nodes, dissect & keep them for the tests.  

Removal of Eye

Procedure
  • Insert the knife through the skin to the dorsal upper eyelid and dissect it circularly.
  • Remove the peri-ocular tissue.
  • Place the entire globe in formalin for histological examination.

Removal of Brain 

Procedure
  • To remove the brain, the skin on the head must first be reflected. With the sharp edge of the knife facing up, cut the skin at the midline of the head.
  • Extend the cut laterally on both sides exposing the underlying skull.
  • Make two cuts medial to each occipital condyle.
  • Extend these cuts rostrally to join with a third cut made just caudal to the two supra-orbital processes.
  • Using the ax & hack saw, open the skull along with these planes/cuts.
  • Use the knife to cut away any dura adhering the brain to the bone.
  • To remove the brain cranial nerves are cut off by gently sliding the knife under and around the brain.
  • Lift the brain out of the skull & inspect the surface for abnormalities.
Sample collection
  • Animals with the history of neurologic signs should have samples collected for 
  • Rabies
  • BSE
  • Toxicology
  • Virology
  • bacteriology & histology.
Specific sampling
  • Remove a 1 cm cross-section of the cerebellum as a sample for a rabies test. Place the sample in a covered Petri dish.
  • To collect the BSE sample, remove a 2 cm cross-section of apex & place it in a large test tube with a screw arm lid. 
  • Take samples from the cerebellum & cerebral cortex for microbiology & toxicology tests. 
  • Place one half of the sample in a plastic bag for virology testing.
  • Place the remaining portions of the brain in formalin & submit for the histology.
  • Bisect the brain into two smaller halves & place them in two separate formalin jars.

Nasal cavities

Procedure
  • Cut across the snout at the level of first cheek tooth
  • Give another cut anterior to the first cut
  • Alternatively, turn the anterior piece of the snout and cut it along the ventral midline to expose the turbinates
  • Examine the exposed surface

Removal of Spinal cord

Procedure
  • In Cattle, Remove the muscles from the right lateral side of the vertebral column
  • In the horse, do it on the left side
  • Remove the exposed transverse processes of the vertebral column until the spinal cord exposed 
  • Beginning with the anterior end of the spinal cord
  • Remove the entire spinal cord.

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