Internal Medicine: Haematology and Transfusion: Approach to Bleeding

Question 1

What needs to be assessed about a bleeding animal?

Answer 1

Quantify blood loss
* dog 80-90ml/kg
* cat 60-70ml/kg

Identify life threatening situations
* hypovolaemic shock
* Severe anaemia
* brain/pulmonary haemorrhage

Establish venous access and collect samples for tests
* PCV
* Blood smear
* Coagualation profile
* Biochem

Question 2

How is a bleeding patient stabilised?

Answer 2

• Control of haemorrhage- wound pressure
• Fluid replacment/blood transfusion (>25% loss)

Question 3

What are the stages to haemostasis?

Answer 3

• Vessel injury
• Vascular contraction
• Primary haemostasis- endothelum, platelets, vonWillebrand factor
• Secondary haemostasis- coagulation cascade, thrombin
• Tertiary haemostasis- fibrinolysis- plasmin

Question 4

What are clinical signs of primary haemostasis defects?

Answer 4

‘Small holes’

Due to lack of platelets/poor function

Question 5

What are clinical signs of secondary haemostasis defects?

Answer 5

‘large holes’
* Results of deficiency in clotting factors
* Tend to present more acutely with life-threatening blood loss
* Subcutaneous or cavity bleeding
* Haematoma formation
* Pulmonary haemorrhage
* Haemarthrosis

Question 6

What In-house lab tests can be done for a bleeding patient?

Answer 6

• Haem
• Biochem
• Whole blood clotting time
• Activated clotting time
• Buccal mucosal bleeding time- if not thrombocytopenia

Question 7

How can primary and secondary coagulation be differentiated?

Answer 7

Primary- test of platlet function or number
* manual platelet count
* mucosal bleeding time
* von Willebrand factor

Test of coagulation
* prothrombin time
* activates partial thromboplastin time
* Activated clotting time

Test of fibrinolysis
* fibrin degredation products
* D-dimers

Question 8

What are disorders of primary haemostasis?

Answer 8

Thrombocytopenia
* platlets < 30x10^9/L

von Willebrand disease
Thrombocytopathia- very rare
Vasulcar disorders- very rare

Question 9

What can cause thrombocytopenia?

Answer 9

Lack of production
* Bone marrow disorders
* Drug toxicosis

Increased consumption
* DIC
* Acute severe haemorrhage

Increased destruction
* Immune mediated: primary or secondary

Increased sequestration- splenic torsion

Question 10

How can thrombocytopenia be inherited?

Answer 10

Inherited macrothrombocytopenia
Breed associated- sighthounds

Question 11

What causes primary and secondary immune mediated thrombocytopenia?

Answer 11

Primary
* IgG binding to platelets
* results in their destrution

Secondary
* Drugs, infectious disease, neoplasia
* ABs most common
* Anaplasma, babesia, lepto, leishmania

Question 12

What is used to diagnose immune mediated thrombocytopenia?

Answer 12

• Full clin history- drugs, travel
• Clinical and opthalmoloigcal exam
• Haematology with blood smear
• Biochem
• Idexx 4DX snap- vector borne
• Thoracic radiographs
• Abdominal US

Question 13

How is IMTP treated?

Answer 13

Secondary- treat underlying disease

Primary- glucocorticoids

Question 14

When is platelet dysfunction suspected?

How is it treated?

Answer 14

Animals who bleed excessively despite normal platelet count and coagulation profile

Drug therapy
* NSAIDs, Aspirin, PBZ and many others

Occurs with hepatic disease, renal disease, hyperproteinaemias

Question 15

1. What can cause acquired von Willebrand disease?
2. Where is vWF synthesised and stored?

Answer 15

1. Severe aortic stenosis
2. Endothelial cells

Question 16

How is von Willebrand disease diagnosed and treated?

Answer 16

• Buccal mucosal bleeding time increased
• Antigenic test
• Genetic testing

Tx
* Cryoprecipitate- whole blood, frozen plasma
* DDAVP- vasopressin- increases vWF release

Question 17

What are acquired and inherited disorders of secondary haemostasis?

Answer 17

Acquired
* vitamin K antagnoism- rodenticide
* toxicity
* liver disease
* DIC

Inherited disorders
* Haemophilia A- more common
* Haemophilia B

Question 18

What cause vitamin K deficincy?
Why does it cause secondary haemostasis?

Answer 18

Rodenticide most common- hepatic failure, decreased absorption

Involved in production/activation of factors II, VII, IX, X

Question 19

1. What are the clinical signs of vit K deficiency
2. How is it diagnosed?
3. How is it treated?

Answer 19

1. 2-5 days after ingestion, epistaxis, melaena, haematoma, haematuira, gingival bleeding
2. Coagulation testing, PT/APTT
3. Vit K therapy- 2-4 weeks, FFP transfusion in emergency

Question 20

What can cause DIC?

Answer 20

• Infectious disease- septicaemia
• Immune mediated disease
• Neoplasia
• Trauma
• Heat stroke
• Cardiac disease
• Angiostronglyus vasorum

Question 21

What are lab abnormalities of DIC?

Answer 21

• Prolonged clotting time
• Reduced ATIII
• Thrombocytopenia
• Schistocytes
• Increased FDPs/D-Dimers
• Decreased fibrinogen
• Poor prognosis

Question 22

What are D-dimers more indicative of in dogs?

Answer 22

Fibrinolysis in DIC