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Tobias ECVS - Krizia > Ch 83 - Spleen > Flashcards

Ch 83 - Spleen Flashcards

1
Q

How much of the BW is the spleen in dogs and cats?

A

0.2%

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2
Q

What are the braod functions of the red pulp and white pulp of the spleen?

A
  • Red pulp: stores erythrocytes and traps antigens. Site of foetal erythropoietis
  • White pulp: SIte of immune response
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3
Q

What is the main anatomincal difference between the spleen in the dog and cat?

A
  • Dogs have a sinusoidal spleen - combo of direct arteriovenous endothelial connections and some areas where RBCs must traverse a region of red pulp between vessels prior to entering the venous side
  • Cats have a nonsinusoidal spleen - direct connection between arterial and venous circulation
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4
Q

List three braod functions of the spleen

A
  • Haematopoiesis
  • Reservoir function
  • Immunologic function
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5
Q

How does the spleen take part in maturation of RBCs?

A

After production in the bone marrow, RBCs spend several days in the spleen maturing
- Intracellular material is removed
- Cell membrane is shaped into a disc
- Cell size is reduced

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6
Q

What are some causes for the spleen to filter out/cull RBCs?

A

Damaged or senile RBCs are filtered out by the spleen due to
- Inelastic cells (spherocytes, acanthocytes)
- RBCs covered with immunoglobulin or intracellular bacteria

Iron is stored in the spleen as ferritin and haemosiderin until transported to the bone marrow for haematopoiesis

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7
Q

How much of a dogs RBC mass and platelet mass can the spleen store?

A
  • 10-20% RBC mass
  • 30% platelet mass
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8
Q

What are the three pools of blood travelling through the spleen?

A
  • Rapid pool: Approx 90% of the blood entering the spleen, takes less than 30 seconds to rejoin systemic circulation
  • Intermediate pool: 9% circulating blood, 8 minutes to rejoin systemic circulation
  • Slow pool: 1% of circulating blood, takes 1 hour
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9
Q

What immune cells is the spleen the largest producer of?

A
  • B-cells
  • T-cells
  • IgM
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10
Q

What is the main method by which the spleen filters microorganisms from the blood?

A

Phagocytosis

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11
Q

List some broad causes of generalised splenomegaly

A
  • Splenitis/inflammation (sepsis, chronic Ix, bacteraemia)
  • Immune reaction or cellular hyperplasia (proliferation of normal cellular components)
  • Congestion (CHF, vascular outflow obstruction, portal hypertension, capsule relaxation)
  • Infiltration (neoplasia, amyloidosis)
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12
Q

List some causes of localised splenomegaly

A
  • Nodular hyperplasia
  • Pseudotumour (benign proliferation of plasma cells, lymphocytes and histiocytes
  • Haemangioma
  • Hamartoma (rare, benign proliferation of mature cells and tissue which are normally present)
  • Abscess
  • Cysts
  • Segmental infarction
  • Siderotic and siderocalcific plaques
  • Neoplasia
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13
Q

List some differentials for hypoechoic and hyperechoic lesions of the spleen on ultrasound

A

Hypoechoic
- Lymphoid infiltration
- Infarction
- Necrosis
- Congestion

Hyperechoic
- Nodular hyperplasia
- Neoplasia
- Fibrosis from healed infarction or haematoma

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14
Q

What ultrasound finding is commonly seen with splenic torsion?

A

Hilar perivenous hyperechoic triangle

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15
Q

How can HSA be differentiated from nodular hyperplasia or haematomas on CT scan?

A
  • HSA will have lower density (lower Hounsfield units) on pre- and post-contrast images
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16
Q

List options of splenic biopsy

A
  • Tru-cut (not if cavitary)
  • Direct surgical (needle biopsy, pinch or punch, partial splenectomy
  • Laparoscopic
  • Transgastric endoscopic sampling
17
Q

What suture/pattern is recommended for splenorrhaphy

A
  • 4-0 to 5-0 monofilament rapidly absorbable in an interrupted mattress pattern
18
Q

List some options for partial splenectomy

A
  • Suture (continuous with second line of continuous or interrupted mattress)
  • CO2 laser
  • Ultrasonic cutting device
  • Vessel sealing device
  • Bipolar electrosurgical devices
19
Q

What is the maximum vessel size for a haemostatic clip?

A

3mm

20
Q

What breeds are overrepresented for splenic torsion?

A

Great Danes, Saint Bernards, GSD, Irish Setters

21
Q

What condition is splenic torsion hypothesised to occur concurrently with?
What additional procedure is strongly recommended during surgery if the patient is stable enough?

A
  • GDV
  • Gastropexy strongly recommended
22
Q

What substances can be released if a splenic torsion if derotated?

A
  • Sequestered blood, thrombi and microthrombi
  • Free radicals
  • TNF
  • vasoactive compounds
23
Q

What % nontraumatic heamoabdomen is from the spleen?
What % are HSA?

A
  • Splenic haemorrhage in 73.6%
  • HSA in 63.3%
24
Q

List DDX for splenic neoplasia in dogs

A
  • HSA
  • undifferentiated sarcoma
  • FSA
  • OSA
  • LSA
  • myxosarcoma
  • MCT
  • Chondrosarcoma
  • Lymphoma
25
Q

What are the 2 most common forms of splenic neoplasis in cats?

A
  • Lymphoma
  • MCT
26
Q

What are some negative prognostic indicators in dogs undergoing splenectomy of mass lesions?

A
  • Marked preoperative thrombocytopaenia or anaemia
  • Intraop ventricular arrhythmias
27
Q

What is the main chemotherapeutic agent used for splenic HSA?

A

Doxorubicin - shown to increase survival after splenectomy

28
Q

What are some other, less common, options for adjunctive Tx of splenic HSA?

A
  • Liposomal encapsulated immunotherapy
  • ## Intraperitoneal and oral continuous low-dose therapy (etoposide/cyclophosphamide/piroxicam)
29
Q

List potential post-op complications after splenectomy

A
  • Haemorrhage
  • Vascular compromise (left pancreatic artery, portal vein thrombosis [PVT])
  • Arrhythmias 35-44%
  • SIRS, ARDS, DIC, PTE (marked preop thrombocytopaenia and anaemia and intraop arrhythmias identified as risk factors)
  • GDV
  • Infection (Splenectomized animals are at higher risk of infection)
  • Oxygen transport - higher risk of hypoxia and ischaemia as have no splenic reserve (important for dogs with airway compromise e.g. BOAS, laryngeal paralysis, restrictive lung disease etc)
  • IF BONE MARROW DISEASE –> catastrophic anemia and death following splenectomy
30
Q

When should VPCs be treated?

A
  • Haemodynamic instability
  • Multiform ECG complexes
  • Very rapid v-tach
  • R-on-T complexes
31
Q

What are hypothetised causes of arrhythmias?
What medication can be sent home if the arrhythmias have not resolved?

A
  • Myocardial ischaemia and hypoxia secondary to reduced cardiac return and hypovolaemic shock as well as impaired venous return from compression (by the mass)
  • Acid-base imbalances, microemboli, myocardial depressant factors associated with pancreatic ischaemia
  • Lidocaine while in hopital
  • Can go home on mexiletine or sotalol
32
Q

What is the maximum vessel size for a haemostatic clip?

A

3mm

Tobias ECVS - Krizia (110 decks)

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