» The Spleen

The spleen lies within the left dorsal part of the abdomen where it is largely, if not wholly, protected by the most caudal ribs. Although the spleen is separated from the ribs by the diaphragm, it is not attached to the diaphragm.

The broad dorsal base lies under the last three ribs, although a small corner may project against the flank. The pointed ventral apex reaches forward to about the 9th or 10th rib, a handbreadth above the costal arch (Fig. 21.6/4). The cranial margin is concave, the caudal margin is convex, and the organ is thus approximately sickle shaped. The parietal surface is generally smooth, though sometimes marked by depressions that may even perforate to the visceral surface. The visceral surface presents three parts. A small dorsal region fits against the left crus of the diaphragm and left kidney and is bound to these by phrenicosplenic and renosplenic ligaments (Fig. 21.8/6 and 7). The remainder of the visceral surface is divided by a ridge along which the splenic artery runs and to which the greater omentum attaches. The narrow strip cranial to the ridge, the gastric surface, is applied to the greater curvature of the stomach (Fig. 21.9). The larger area caudal to the ridge, the intestinal surface (Fig. 21.9/1), is related to various parts of the intestinal mass.

The position of the spleen naturally varies with respiration. Usually only the caudal margin is within reach on rectal exploration (see Fig. 22.23B/10); a greater part becomes accessible when the stomach is distended.

The thick capsule of spleen contains a considerable amount of smooth muscle, which relaxes to allow the engorgement of the spleen. This occurs in certain diseases and is very obvious in animals that have succumbed to anthrax. The organ is steel blue on first removal from the fresh carcass but turns reddish brown on exposure to the air. This color is derived from the red pulp that forms the bulk of the parenchyma. The white pulp that flecks the red is not normally visible to the naked eye. In addition to being a reservoir for red blood cells, the spleen is a major part of the immune system.

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Source: Singh Baljit. Dyce, Sack and Wensing's Textbook of Veterinary Anatomy. 5th edition. — Elsevier,2018. — 1606 p.. 2018

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