Haematology and Haemostasis Module 2

Question 1

What is the most common acquired haemostatic defect seen in dogs?

Answer 1

Immune mediated thrombocytopenia

Question 2

Causes of IMTP?

Answer 2

Lack of production - BM problem secondary to various drugs/toxins
Increased consumption - sequested or utilised - extensive bleeding, DIC, hyperspenisms or splenic sequestrum

Question 3

What level will result in spontaneous bleeding in dogs

Answer 3

levels below 20x10^9 L

Question 4

What breed has macrothrombocytopenia?

Answer 4

CKCS

Question 5

What are investigations needed for IMTP?

Answer 5

Haematology - looking for signs of BM suppression
Coagulation problem - investigate for DIC, consumptive disease
Imaging - neoplasia
Infectious disease - parasites
A-vasorum
D-dimers

Question 6

IMTP treatment

Answer 6

1. Preds +/- second immunosup (mycophenalate)
2. Transfusions usually if bleeding into somewhere it shouldnt like brains/lungs
3. vincristine one off - kills macrophages
4. Vincaloaded platelets

Question 7

What is the most common inherited haemostatic disease?

Answer 7

Von willebrands disease

Question 8

What are the three types of Von Willebrands Disease

Answer 8

Type 1 - relative defiency of vWF - GSDs, Dobermans, Standard poodles - haematoma/post surgical bleeding
Type 2 - Normal vWF antigen levels but the absence of large multiuser forms and decreased collage bindings which makes protein ineffective - moderate bleeds
Type 3 - Almost complete lack of vWF - spontanous death after severe bleeds - shetlands, sheepdogs, scotties, chesapeake terriers

Question 9

Treatmnet of Von Willebrands disease?

Answer 9

Cryoprecipitate
FFP
Desmopressin

Question 10

What are common thrombopathies due to?

Answer 10

Inherited defects in platelet function - due to defects in platelets in signalling/activation and are rare
Genetic tests
CKCS, persian cats, great prenees, otterhound, spitz

Question 11

What are 6 causes of secondary haemostatic disorders?

Answer 11

1. Factor 12 deficiency - common in cats - no bleeding rpoblems are seen in association with this problem
2. Factor 11 deficiency - Kerry Blue Terrier - Haemophillia C - not very stable fibrin clots due to poor crosslinking
3. Factor 9 (haemophilia B-cats) Factor 8 (haemophilia A-GSD)
   -Moderate bleeding tendencies, aPTT elevations - sexlinked in males mostly
4. Anti-coag toxicity
   - Vit K needed for formation of factors 2, 7, 9, 10 - 7 has the shortest half life
   PT prolongations before aPTT - Plasma + FFP to tx if active bleeding
5. Liver disease - significant cholestasis leading in adequate Vit K absorption (fat soluble), lack of clotting factors (fibrinogen less likely to be affects due to amount of production by the liver)
6. consumptive (DIC) and dilutional (fluids) diseases

Question 12

What are 3 pro-coagulant drugs?

Answer 12

1. Aminocaproic acid TXT class of dryg
2. TXT
3. Yunan Baiyo - control haem not ameanable to haemangiosarcoma

Question 13

What are the mechanisms of thrombosis?

Answer 13

Virchows Triad
Stasis of blood flow - hypoperfusion, immobility, dilation
Hypercoagulability - inflammation can cause increased platelet activation and abnormal tissue factor expression
Endothelial injury - vessel walls prevent exposure of tissue factor and regulates coagulation and anti-coagulation (trauma, inflam, neoplasia, athetersclerosis)

Question 14

Treatment to of thrombosis

Answer 14

1. Pain relief
2. Maximise perfusion
3. Thormbolysis - not recommended due to secondary haem SE - rapid perfusion leading to reperfusion injury
4. Thrombophylactic treatments - anticoags v. anti-platelet drygs

Question 15

Examples of thormboembolic disease states?

Answer 15

1. IMHA
2. FATE
3. DIC
4. PTE
5. PLE/PLN
6. Pancreatitis
7. Cushings
8. HypoT4
   9 Neoplasia

Question 16

How is IMHA diagnosed?

Answer 16

Confirm haemolysis (extra or intra) and confirm immune targeting

Immune targeting can be confirmed by
- Slide agglutination
- Spherocytes
- Positive coombs test

Question 17

IMHA Treatment

Answer 17

1. Steroids mainstay 2mg/kg/day (2mg/kg/BID cats) - up to 5 days for improvement
2. Secondary agent to help with signs of steroids and but takes time to take effect (1-3 weeks depending on drugs) - ciclosporin, azothiaprine, mycophenalate
3. doxy/retroviral if infection suspected
4. anti-clotting - anti-coagulants (rivaroxaban/heparins) > anti-platelet (clopidrogrel/aspirin)

No gastroprotectants unless signs of ulceration

Question 18

How is intravascular and extravascular haemolysis differentiated?

Answer 18

Intravascular haemolysis: Red cells are lysed within blood. Characterised by free Hb in plasma and urine

Extravascular haemolysis: Red blood cells are lysed after removal from circulation. characterised by increased bilirubin, urinary bilirubin