Lien (Splen)
The equine spleen is a large, tongue-shaped organ weighing 1-2 kg located on the left side of the abdomen. It is attached to the stomach by the gastrosplenic ligament and to the left kidney by the nephrosplenic ligament. It is the largest lymphoid organ in the body and serves dual functions: as a secondary lymphoid organ filtering blood-borne antigens and as a blood storage reservoir unique in its capacity among domestic species. The equine spleen can store up to 12 liters of red blood cells (approximately one-third of the total red blood cell volume), which are released into circulation during exercise or excitement by capsular smooth muscle contraction under sympathetic control.
Splenic disease is uncommon but can include rupture, neoplasia, or torsion. The spleen's blood storage capacity is relevant in evaluations of exercise physiology and anemia. Diagnosis uses ultrasound and clinical examination.
## Overview Splenic rupture or hematoma causes bleeding into the abdomen. It may result from blunt trauma or spontaneous rupture of a tumor. Signs of acute blood loss include colic, elevated heart ra
## Overview Splenic lymphosarcoma is infiltration of the spleen by malignant lymphocytes. The spleen is frequently involved in the multicentric form of equine lymphoma. Signs include an enlarged sple
## Overview Splenic hemangiosarcoma is a malignant tumor of blood-vessel lining cells. It is less common in horses than in dogs but can cause recurrent colic, episodic weakness, and hemoabdomen from
## Overview A splenic abscess is a focal infection within the spleen, often from hematogenous spread of Streptococcus species (including bastard strangles) or secondary to trauma. Signs are nonspecif
Sudden collapse or pale mucous membranes after trauma should be evaluated immediately. The spleen's blood storage function is normal and important for exercise.
## Overview Splenic rupture or hematoma causes bleeding into the abdomen. It may result from blunt trauma or spontaneous rupture of a tumor. Signs of acute blood loss include colic, elevated heart rate, pale mucous membranes, weakness, and a dropping packed cell volume. Abdominocentesis yields bloody fluid. ## Causes Trauma or neoplasia. ## Diagnosis Ultrasound and abdominocentesis. Serial packed cell volume monitors ongoing bleeding. ## Treatment Stabilization, blood transfusion if needed, and surgery (splenectomy) in selected cases. Many traumatic hematomas are managed medically if bleeding stops. ## Recovery and Prognosis Variable. Stable hematomas can resolve. Ongoing hemorrhage or neoplasia carries a poorer outlook. ## Prevention Trauma avoidance. Signs include: acute colic; tachycardia; pale mucous membranes; weakness or collapse; hemorrhagic peritoneal fluid; dropping packed cell volume
## Overview Splenic lymphosarcoma is infiltration of the spleen by malignant lymphocytes. The spleen is frequently involved in the multicentric form of equine lymphoma. Signs include an enlarged spleen palpable on rectal examination, weight loss, anemia, intermittent fever, and elevated globulins. Other organs are often affected simultaneously. ## Causes Lymphoid neoplasia. ## Diagnosis Rectal palpation, ultrasound, and biopsy or cytology. ## Treatment Palliative corticosteroids or chemotherapy. Prognosis is poor. ## Recovery and Prognosis Poor. Survival is typically weeks to months. ## Prevention None. Signs include: enlarged spleen palpable per rectum; weight loss; anemia; intermittent fever; hyperglobulinemia
## Overview Splenic hemangiosarcoma is a malignant tumor of blood-vessel lining cells. It is less common in horses than in dogs but can cause recurrent colic, episodic weakness, and hemoabdomen from spontaneous rupture. Ultrasound shows a splenic mass, and the packed cell volume drops with bleeding. ## Causes Neoplastic. ## Diagnosis Ultrasound, abdominocentesis showing blood, and histopathology. ## Treatment Splenectomy in selected cases. Metastasis is common. Prognosis is poor. ## Recovery and Prognosis Poor. ## Prevention None. Signs include: recurrent colic; episodic weakness; hemoabdomen; dropping packed cell volume; large splenic mass on ultrasound
## Overview A splenic abscess is a focal infection within the spleen, often from hematogenous spread of Streptococcus species (including bastard strangles) or secondary to trauma. Signs are nonspecific: intermittent fever, weight loss, recurrent colic, and elevated fibrinogen. Ultrasound shows a hypoechoic mass in the spleen. Prognosis is poor. ## Causes Bacterial seeding, most often Streptococcus. ## Diagnosis Ultrasound and aspiration with culture. ## Treatment Long-term antibiotics and, when feasible, surgical drainage or splenectomy. Survival is limited. ## Recovery and Prognosis Poor. Many cases do not survive. ## Prevention Strangles control. Signs include: intermittent fever; weight loss; recurrent colic; elevated fibrinogen; hypoechoic splenic mass on ultrasound
Splenic disease is uncommon but can include rupture, neoplasia, or torsion. The spleen's blood storage capacity is relevant in evaluations of exercise physiology and anemia. Diagnosis uses ultrasound and clinical examination.
Sudden collapse or pale mucous membranes after trauma should be evaluated immediately. The spleen's blood storage function is normal and important for exercise.
See the Spleen on our interactive 3D horse model. Open 3D Model