Overview
The bovine spleen (lien) is an elongated, thin plate with rounded edges. Its capsule is thick and gives off trabeculae with smooth muscle fibres. It filters the blood, removes ageing erythrocytes and takes part in the immune response.
Topography
- Position: on the left side, in the cranial abdomen, covered by the last ribs. Its parietal surface faces the diaphragm; its visceral surface rests on the dorsal sac and the atrium of the rumen.
- Attachment: unlike in the dog or cat, a wide area of the visceral surface adheres directly to the rumen with no peritoneum in between, and the dorsal end is attached to the diaphragm. It is therefore not very mobile.
- Ends: the dorsal end lies under the vertebral ends of the last ribs; the ventral end runs cranioventrally.
Clinical relevance
- Splenic abscesses: a reticular foreign body migrating to the left can reach the spleen; it is a complication of traumatic reticuloperitonitis.
- Anthrax (Bacillus anthracis): sudden death with marked splenomegaly, a dark, soft pulp, and unclotted blood from the natural orifices. When it is suspected the carcass is not opened, to avoid releasing spores.
- Blood parasites: anaplasmosis (Anaplasma marginale) and babesiosis destroy erythrocytes and enlarge the spleen.
- Lymphoma: in enzootic bovine leukosis the spleen can enlarge greatly and may rupture.
- Examination: its position under the ribs and its attachment to the rumen prevent palpation; it is assessed by ultrasound through the last left intercostal spaces.