Splenic Disorders Flashcards
Where is the spleen located in small animals?
Cranial abdomen, towards the left hand side
Describe the anatomy of the spleen including attachments
Dorsal head fixed in abdomen by gastrosplenic ligament
Ventral tail which is more mobile
Smooth muscle capsule = able to contract and swell
Where does the splenic artery arise from?
Celiac artery and divides into -25 small hilar arteries which enter the spleen on the concave surface
Where does the splenic vein drain to?
Portal vein
What do the important branches of the splenic artery/vein supply?
- Left limb of the pancreas
- Greater curvature of the stomach
- Fundus of the stomach
Which vessels rupture during GDV?
Short gastric vessels
How well can dogs and cats survive without a spleen?
Normally unlike humans
Should still try to preserve e.g. benign disease
What are the functions of the spleen?
- RBC maintenance
- Iron metabolism
- Blood reservoir
- Haematopoiesis
- Immune function
Describe the role of the sleep in RBC maintence
Filtration of blood and phagocytosis
Remodelling RBCs
Removal of intravascular erythrocytic inclusions e.g. heinz bodies
Describe the role of the spleen in iron metabolism..
Significant iron stores due to removal of old/damaged RBCs
Describe the role of the spleen as a blood reservoir
Store 10-20% blood volume
Stores platelets
RBCs available during haemorrhage, haemolysis and strenuous exercise (stitch!)
Describe the role of the spleen during haematopoeisis…
Haematopoietic functions in adults to help when bone marrow cannot carry out normal role
Describe the role of the spleen in terms of immune function…
Major site of clearance of microorganisms and providing immune response
Protects again septicaemia
What is a possible effect of a GDV on the spleen?
Sometimes GDV can tear the short gastric vessels and gastrosplenic ligament
Causes head to the spleen to be more mobile and necrotic
Is a total or partial splenectomy performed more commonly?
Total splenectomy
Neoplasia common
Describe a total splenectomy…
- Large ventral midline incision
- Begin at tail end
- Ligate and transect gastric, left gastrosplenic a+v and splenic a+v distal to branch supplying pancreas
- Transect gastrosplenic ligament
What can make a total splenectomy more difficult?
Lots of adhesions to ruptured splenic mass
Distorted anatomy due to torsion
Mistakenly ligating branch to left limb of the pancreas
Pre-operative considerations when performing total splenectomy…
Met checks - malignancy? IV fluids stabilisation if in shock Blood transfusion if PCV <20% High risk of cardiac arrhythmias (particularly with anaemia and haemabdomen) Coagulation tests
When can a partial splenectomy be performed?
Localised, benign disease
Describe a partial splenectomy
- Ligate and transect vessels supplying disease portion
- Squeeze splenic tissue along demarcation between ischaemic and normal
- Place forceps on flattening portion
- Divide spleen and removed disease portion
- Place two rows of continuous overlapping mattress sutures
- Close cut end with continuous suture pattern
OR
Stapling device
What should you do in a splenectomy to cope with increased risk of cardiac arrhythmias?
Monitor with ECG before and after surgery
Treat hypovolaemic shock
Consider antidysrhythmic drugs
Why should you do coagulation tests with a splenectomy?
Disseminated intravascular coagulation (DIC) can occur with both neoplastic splenic lesions and splenic torsions
Complications associated with splenectomy…
Haemorrhage
Ischaemic pancreatitis and gastritis
Cardiac arrhythmias
Is localised splenomegaly more common in dogs or cats?
Dogs
Is generalised splenomegaly more common in dogs or cats?
Cats
Non-neoplastic causes of localised splenomegaly…
Haematoma Abscess Cyst Nodular hyperplasia Infarcation
Neoplastic causes of localised splenomegaly…
Benign:
- Haemangioma
- Leiomyoma
- Fibroma
- Lipoma
Malignant:
- Haemangiosarcoma
- Fibrosarcoma
- Leiomyosarcoma
- Any sarcoma!
Non-neoplastic causes of diffuse splenomegaly….
Infectious (bacterial, viral, fungal, parasitic)
Congestion
- Drugs e.g. barbiturates (relaxes smooth muscle capsule)
Splenic torsion/GDV
Right sided heart failure
Neoplastic causes of diffuse splenomegaly…
Acute and chronic leukaemia Systemic MCT (cats) Lymphoma Multiple myeloma Malignant histiocytosis
When would a splenectomy be performed in terms of IMTP?
If the animal is refractory to treatment with immunosuppressive drugs
Is an FNA useful for diagnosis of localised haematoma/haemangiosarcoma?
No - just aspirate blood in the middle of the mass so very unlikely to be diagnostic
How can you differentiate between and splenic and liver mass?
Ultrasound
Radiography
What is the most common malignant splenic tumour in dogs? Which breed is most susceptible?
Haemangiosarcoma
GSD
Where do splenic haemangiosarcomas frequently metastasise to?
Liver Omentum Mesentry Brain Right atrium Subcutaneous tissue
What do 25% of dogs with splenic haemangiosarcoma also have?
Concurrent right atrial haemangiosarcoma
How can you differentiate between haemangioma, haemangiosarcoma and haematoma?
Grossly indistinguishable
All should have thoracic radiographs to look for mets
What treatment is recommend for dogs with haemangiosarcoma without mets? What is the expected survival time?
Splenectomy
Only palliative
Survival only 3-12 weeks
What is the prognosis for dogs with haemangiosarcoma that have adjunctive treatment as well as surgery?
<10% survive past 1 year
How long does chemotherapy prolong life following surgery for removal of a haemangiosarcoma?
Up to 6 months
What chemotherapy protocol would you use for haemangiosarcoma following surgery?
Cyclophosphamide/doxorubicin protocol for 6 months
If a dog present with haemabdomen what is your number one differential?
Haemangiosarcoma
Which breeds is splenic torsion most common in?
Relatively uncommon
Large/giant breeds
Great danes/irish setters
How do dogs with isolated splenic torsion acutely present?
Progressive abdominal pain
Distension
Shock
How do dogs with splenic torsion chronically present?
Vague and intermittent signs so difficult to diagnose
What is splenic torsion?
Spleen twists on it’s vascular pedicle, occluding hilar vessels
What is the most useful method of diagnosis for splenic torsion?
ULTRASOUND
- Unique pattern of linear echoes separating large anechoic areas = snowstorm
- May visualise twisted pedicle/thrombosis
How should you approach splenic torsion during surgery?
Do not untwist pedicle (toxin release)
Clamp pedicle
Get spleen out
Divide and ligate pedicle without untiwisting
What is the prognosis for splenic torsion?
Excellent if splenectomy performed correctly
What is the most common cause of splenic torsion?
Iatrogenic during surgery
Isolated splenic injury following blunt trauma (rare)
Why is splenic trauma not usually treated surgically?
Most haemorrhages are either self-resolving with conservative stabilisation
OR they are so severe fatal before surgery
What does severe or persistent haemorrhage following splenic surgery require?
Ligation of splenic vessels
Followed by partial/total splenectomy
What may you see following rupture of the spleen?
Multiple splenic nodules called splenosis throughout the abdomen