Small Animal Splenic Disorders

Question 1

Where is the spleen located?

Answer 1

In the cranial abdomen towards the left hand side

Question 2

What is the anatomy of the spleen?

Answer 2

Dorsal extremity (head) which is fixed by gastrosplenic ligament and a ventral extremity (tail) which is relatively more mobile

Question 3

How are structure and function of the spleen linked?

Answer 3

Smooth muscle capsule so it can significantly contract or swell in size

Question 4

What is the blood supply to the spleen?

Answer 4

Splenic artery arises from celiac artery and divides into approximately 25 small hilar arteries which enter the spleen on its concave surface
Splenic vein drains into the portal vein

Question 5

What are some important branches of the splenic artery/vein?

Answer 5

Left limb of the pancreas
Greater curvature of the stomach (left gastroepiploic)
Fundus of the stomach (short gastic)

Question 6

What is the function of the spleen?

Answer 6

Red blood cell maintenance, iron metabolism, blood reservoir, haematopoiesis, immune functions

Question 7

How does the spleen perform red blood cell maintenance?

Answer 7

Filtration of blood and phagocytosis, remodelling of red blood cells, removal of intra-erythrocytic inclusions

Question 8

How does the spleen contribute to iron metabolism?

Answer 8

Significant iron stores result from continuous removal of old or damages red blood cells

Question 9

How does the spleen act as a blood reservoir?

Answer 9

10-20% blood volume stored in dogs and cats which are readily available in case of acute blood loss/haemolysis

Question 10

How does the spleen act as a haematopoietic organ?

Answer 10

Can resume haematopoietic functions in adult animals to help out when bone marrow cannot carry out its normal haematopoietic role

Question 11

What are the immune functions of the spleen?

Answer 11

Major site for clearance of micro-organisms and providing an immune response protecting against septicaemia

Question 12

Where are the functions of the spleen carried out?

Answer 12

First four functions carried out in red pulp and immunological functions carried out in white pulp

Question 13

Why is a splenectomy performed?

Answer 13

Due to suspected neoplasia or due to rupture

Question 14

How is a splenectomy performed?

Answer 14

Large ventral midline abdominal incision, begin removal at tail end double ligating vessels, when reach the head try and preserve short gastric vessels and transect gastrosplenic ligament

Question 15

What is the quick way of performing a splenectomy?

Answer 15

Ligate the short gastric vessels and left gastrosplenic a + v and the splenic a + v distal to the branch supplying the pancreas

Question 16

When is a partial splenectomy performed?

Answer 16

Localised benign disease

Question 17

How is a partial splenectomy performed?

Answer 17

Hilar vessels to diseased portion are ligated and transected resulting in an obvious demarcation between ishcaemic and normal spleen which is used as a guide for resection then transect the spleen using one of two methods

Question 18

What are the two methods of transecting the spleen in a partial splenectomy?

Answer 18

Squeeze along demarcation towards end to be removed and place forceps on flattened portion, divide spleen between the forceps and place two rows of mattress sutures in a continuous overlapping pattern and close cut end of spleen using continuous suture pattern
Use a stapler

Question 19

What are the perioperative considerations for splenectomy?

Answer 19

High risk of cardiac arrhythmias, coagulation tests should be performed, large abdominal incision should be made, abdominal retractors and suction make job easier, examine entire abdomen for neoplasia, need lots of haemostatic forceps and swabs, measure blood loss

Question 20

How is blood loss measured?

Answer 20

Measure blood in suction bottle and weight swabs (1ml blood = 1.3g)

Question 21

What other operation should be considered in large deep chested dogs following splenectomy?

Answer 21

Gastropexy to reduce risk of GDV

Question 22

What are the potential complications of splenectomy?

Answer 22

Haemorrhage due to technical failure or DIC
Ischaemic pancreatitis and gastritis
Cardias arrhythmias
Possible increased risk of infection

Question 23

What are some causes of localised splenomegaly?

Answer 23

Haematoma, abscess, nodular hyperplasia, infarction, cyst, haemangioma, leiomyoma, fibroma, lipoma, haemangiosarcoma, fibrosarcoma, leiomyosarcoma

Question 24

What are some causes of diffuse splenomegaly?

Answer 24

Infection, congestion due to drugs/splenic torsion/GDV/right sided heart failure, acute and chronic leukaemia, systemic mast cell tumour, lymphoma, multiple myeloma, malignant histiocytosis, immune-mediated thrombocytopaenia

Question 25

How useful is an FNA in diagnosing splenic disease?

Answer 25

May be very useful in differentiating certain causes of diffuse splenomegaly however often just produces blood when aspirating localised haematoma or haemangiosarcoma

Question 26

What are the characteristics of haemangiosarcomas?

Answer 26

Most common malignant splenic tumour in the dog
GSD at increased risk
Aggressive and frequently metastasise to liver, omentum, mesentery, brain, right atrium and subcutaneous tissue

Question 27

How is haemangiosarcoma diagnosed?

Answer 27

Grossly indistinguishable from haemangioma or haematoma and requires pathology
All dogs should have thoracic radiographs/CT to check for metastasis

Question 28

What is the treatment for haemangiosarcoma?

Answer 28

Splenectomy is palliative with survival of 3-12 weeks
Post operative chemotherapy prolongs life for around 6 months normally using cyclophosphamide/doxorubicin protocol for 6 cycles

Question 29

In which breeds is splenic torsion seen in?

Answer 29

Deep chested breeds such as Great Danes/Irish Setters

Question 30

What happens in a splenic torsion?

Answer 30

Spleen twists on its vascular pedicle occluding the hilar vessels

Question 31

How do dogs with splenic torsion present?

Answer 31

Acutely with progressive abdominal pain, distension and shock
Chronically with vague intermittent signs

Question 32

How is a dog with splenic torsion diagnosed?

Answer 32

Ultrasound revealing a large spleen with unique pattern of linear echos separating large anechoic areas ‘snowstorm appearance’

Question 33

What is the treatment for splenic torsion?

Answer 33

Splenectomy but without untwisting as will release toxins into the blood stream causing shock

Question 34

What is the prognosis for splenic torsion?

Answer 34

Excellent after splenectomy

Question 35

How does splenic trauma occur?

Answer 35

Isolated blunt trauma from RTA or fall is uncommon

Laceration from a penetrating injury or iatrogenic injury is also possible

Question 36

Why is surgical treatment of splenic trauma uncommon?

Answer 36

Either resolves itself or the animal’s injuries are fatal

Question 37

How can surgical interventions be used to treat splenic trauma?

Answer 37

Mild haemorrhage = splenic capsule sutured or omentum sewn over lesion
Severe haemorrhage = ligation of splenic vessels involved then partial/total splenectomy

Question 38

What may happen after rupture of the spleen?

Answer 38

Multiple small splenic nodules called splenosis may be seen throughout the abdomen