Postmortem Examination

Definition

• Postmortem or necropsy is the systematic exposure and critical examination of the carcass after death of animal.
• Objective: To determine the cause of death or study the morbid anatomy.
• The post mortem examination is one of the most informative investigations in medicine and provides information about illness and health that could not be discovered in any other way.

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Note: PM should be done immediately after death to minimize postmortem autolysis and putrefaction.

IMPORTANCE OF NECROPSY�

• History, clinical signs, and necropsy aided by laboratory tests often determine the nature of an animal's disease.
• Necropsies playa vital role in understanding diseases and their pathogenesis. Such an understanding is essential for developing and applying rational therapeutic and control measures.
• A skillfully conducted and intelligently interpreted necropsy will give the client (especially livestock owners) a surprising amount of satisfaction and confidence in his veterinarian.

• In disease surveillance, collection of data for statistical analysis of pathological conditions may provide answers to management problems in large livestock operations or uncover a subclinical problem before it becomes economically costly.
• Co-existing conditions may also be revealed including inheritable problems whose early recognition may benefit other family members

• The benefits of a post mortem examination extend beyond providing information to individual families. Information obtained during the examination can also:
• Provide information which can help doctors treat other patients with the same kind of illness.
• Facilitate in assessing and improving the quality of medical care.
• Be very valuable for ongoing medical training purposes.
• Give vital research information into the nature, causes and prevention of disease.
• Assist public health planning by providing information as to why and how people have died and what they have died from.
• Most errors in diagnosis are not the result of ignorance, but of haste, carelessness, or apathy

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Steps in postmortem examination:�

External examination of carcass

• Position of animal at time of death.
• General appearance of carcass, namely bloat, ngor, postmortem decomposition, and dehydration.
• Thriftiness or apparent nutritional status.
• Condition of hair coat and presence of external parasites.
• Color and appearance of all visible mucous membranes.
• Presence or absence of discharges from all body openings and mammary glands (discharges, color, size, etc.).
• Evidence of swellings, wounds, hernias, and fractures.

Positioning of animals:�

• Ruminants are placed in left lateral recumbency while equine carcass is placed with its right side downward prior to the necropsy examination (the bulky rumen and the equine cecum and colon are handled best in these positions)
• Small animals (canine, feline, etc.) are positioned with the dorsum downward and the head to the left of the prosector.

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Opening of carcass�

• Start a midline incision extending from the tip of the jaw to the pubis.
• Then lift the front leg and cut the muscle attachments close to the thorax and lay the leg dorsally and flat.
• Grasp the upper rare leg; incise the muscles and disarticulate the coxofemoral joint and lay the leg dorsally and flat on the surface.

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Skin the carcass�

• Reflect the skin ventrally along the entire length of the initial incision.

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Opening the abdominal cavity�

• Open the abdomen by cutting the muscles along the costal arch from the transverse process of the spinal column to the sternum and caudally along the linea albea to the brim of the pelvis.

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Remove the rib cage:

1. The rib cage is removed by cutting the ribs extending from the xiphoid cartilage cranial to thoracic inlet
2. The next cut begins from the most dorsal aspect of the first rib (dorsal to the reflected neck organs), and extends caudally to the transverse process of the first lumbar vertebra.
3. After the ribs are detached along these lines, the severed rib cage is removed by cutting it from the diaphragm.

Remove the organ from thoracic cavity

• Grasp the tongue, esophagus, trachea, and reflect the thoracic viscera (heart, lungs, and thymus) from the thoracic cavity.

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Remove the organ from abdominal cavity

Remove the liver and diaphragm

• Remove these organ together by cutting the diaphragm from its costal attachment.

Removal of organ form the pelvic cavity following pelvic cut

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Removal of kidney�

Grasp the right kidney and cut laterally and anteriorly to the kidney and adrenal.

Removal of Brain�

• The brain should be examined in all cases in which the clinical history suggests neurological disturbances.
• Leave the head attached to the spinal column and reflect the skin
• from the head. This may be a possible compromise, but an easy way to
• remove the brain is a near mid-saggital incision (Y4 to Y2" to either side
• of the midline). Saw the head from the ventral side and extend the incision
• posteriorly to the level of the occipital condyle (Fig. 2-21).
• After the calvarium and brain are exposed, each half is removed by gentle
• traction and passive gravitational force. The brain will peel out of the
• calvarium after cutting the cranial nerves and dural attachments with a
• pair of curved pointed scissors. Do not squeeze or handle the brain
• roughly, because it is easily damaged.