Pinniped Necropsy: Abdominal Cavity

As noted earlier, the diaphragm separates the thoracic cavity from the abdomen. By now, both cavities will have been opened, and the dissection should proceed with the removal of the liver. The liver is multi-lobular and maroon. Located over the stomach, the liver is fairly large in pinnipeds, encompassing the majority of the abdominal cavity. The liver should be removed before the gall bladder is incised to prevent contamination, and the parenchyma can be examined by bread-slicing (this technique will come in handy for viewing the inside of most organs). Examine the color pattern and texture of the lobes and parenchyma, all the while searching for parasites (especially in bile ducts).

The gall bladder is a round and green organ that is located ventrally between the right and central lobes of the liver. The gall bladder is a thin walled sac that stores and secretes bile. By cutting into the duodenum (first part of the small intestines), it can be determined whether or not the gall bladder is secreting bile. Check for gall stones. The spleen is a slightly discoid, but mostly oblong purple-white organ found underneath the stomach along the left body wall. Pinniped spleens may be serrated or have irregular margins, a normal sight. Examine the organ and bread-slice. The pancreas is located in the curve of the duodenum and is a lobulated, peach-colored tissue. Look for changes in color in the parenchyma and examine the ducts for parasites. Furthermore, the pancreas is attached to the mesentery, a translucent, malleable but firm connective tissue that is in turn attached to the intestines. Examine the mesentery for any adhesions, and note if there is congestion of the vessels. Lymphatic vessels may be distended with a milk-like fluid if the seal has recently eaten. The mesenteric lymph node can be found centrally on the mesentry and is a large, finger-like lymph node that tends to have a more pronounced cortex and medulla than previously described lymph nodes. As is usual, note any changes in the interior (by cross-section cutting) and exterior aspects of this lymph node.



Next, locate the right and left adrenal glands in situ, as they may be hard to find without the kidney as a guide. These two glands are located anterior to the cranial pole of each kidney, and are small, maroon tissues with irregular furrows over their surface. Pull the tissue distally and cut connecting tissue to remove the adrenal glands. Measure and weigh each adrenal gland and then cut them in half. The medulla should be distinctly darkened, with a lighter cortex. Look for the aperture of the medulla. A normal, pen-tip sized opening indicates usage of the glands. The kidneys are a darker shade of maroon and are reniculated (possessing miniature kidneys). They are attached to the caudal dorsal abdominal wall and are enclosed by the capsule, a connective tissue. Longitudinally incise the capsule and reflect each half to reveal each kidney. Detach them from the abdominal wall and examine the internal and external structure, making note of any stones. also observe the medulla:cortex ratio and the degree of differentiation between the two. Normal reniculi are clearly demarcated and clustered together within the kidney.

The bladder is a relatively small, light pink and found anterior to the pelvic bone along the ventral body wall. If urine is present in the bladder, it may appear thin and slightly translucent, as opposed to a thick-walled appearance when not full. Extract urine aseptically from the bladder, noting the amount, color and consistency, and then remove the bladder. Cut along the length of the organ to expose the mucosal surface and note the color of this mucous.

In past necropsies, most notably the harp seal (P. groenlandica), the stomach held the greatest clues for cause of death, and so special care must be taken to ensure that the stomach is thoroughly analyzed. Tie off both ends of the stomach with twine before removal, one knot at esophagus-stomach interface, the other just below the duodenum. Cut beyond both knots and then examine the serosal (external) surface of the stomach, noting any lesions, or changes in color. If there is a pathological condition, the perigastric lymph node may be enlargened. Incise along the wall with the greatest curvature, and note the stomach contents. These contents can range from food, to fluid, parasites, or even foreign objects. Collect a sample and then run the contents through a sieve to collect solid materials that may have gone unnoticied. Photograph any foreign objects and save them. Now empty, the stomach lining can be examined. Note the mucosa and look for ulcers, parasites and lesions. Weigh the stomach when it is emptied.

The intestines are the last of the abdominal cavity organs to be examined so that they do not contaminate the body. The small intestines should be serosally examined, areas of hemmoraghing or discoloration noted. The inside can be examined by spot checking: select 5-10 random areas and then cut down 10 centimeters of their length, noting color, contents, thickness etc. The large intestines are located by finding the ileo-ceco-colic junction, which is a ridged section between the small-diameter small intestines and the large intestines. Repeat spot checking for both the large intestine and the colon. A sample of feces should be taken from the colon for toxicology analysis.

The last topic to tackle in Pinnipeds is the nervous and reproductive systems. As the endocrine system is spread out all over the body, the relevant glands associated with these systems will be covered, too. Pituitary gland, my eye is on you.