Hemostasis

Question 1

Define Hemostasis…

Answer 1

sealing an injured vessel to prevent blood loss
Can be: 
1. Physiological
2. Surgical
3. Pathological

Question 2

What is the Pathological form of Hemostasis?

Answer 2

Thrombosis

Question 3

What are the requirements for Thrombosis?

Answer 3

1. vascular wall -> endothelium
2. platelets -> primary CLOT and THROMBUS component
3. coagulation cascade

Question 4

True/False: The extracellular matrix has low thrombogenicity.

Answer 4

False - the extracellular matrix has high thrombogenicity

Question 5

What is Endothelin?

Answer 5

A secretion factor that is a potent endothelium-derived vasoconstrictor.

Question 6

What is the end result of Primary Hemostasis?

Answer 6

Creating a Primary Hemostatic Plug

Question 7

What are the 5 MAIN steps of Primary Hemostasis following injury?

Answer 7

1. Platelet Aggregation
2. Change in Platelet shape
3. Granule Release
4. Recruitment
5. Primary Hemostatic Plug formation

Question 8

What is the purpose of Secondary Hemostasis?

Answer 8

Creating THROMBIN

Question 9

Why is thrombin so important?

Answer 9

It cleaves circulating fibrinogen into fibrin.

It also recruits more platelets and stimulates further granule release.

Question 10

What does Fibrin do?

Answer 10

Fibrin wraps around the aggregated platelets and forms the Secondary Hemostatic Plug

Question 11

What is the difference btw the Primary Hemostatic and Secondary Hemostatic Plug?

Answer 11

Secondary Hemostatic Plug lasts longer!

Question 12

What are the 2 molecules released that limit the hemostatic plug to the site of injury?

Answer 12

1. t-PA

2. thrombomodulin

Question 13

If you do NOT stop the coagulation cascade, it may lead to…

Answer 13

Thrombus

Question 14

What is Thrombus?

Answer 14

Aggregate of platelets, fibrin and entrapped blood cells.

Question 15

What is the difference between a Thrombus and a Blood Clot?

Answer 15

Thrombus is attached to the vascular wall

Question 16

What are the distinguishing characteristics of a thrombus vs. a post-mortem blood clot?

Answer 16

Thrombus:
surface: more dull and granular
attached to the vessel wall

Post-Mortem Clot:
Red/Pale/Shiny and smooth
Not attached to the vessel wall

Question 17

Cats with Cardiomyopathy will have a thickened left side of the heart. Where is a thrombus more likely to develop?

Answer 17

in the Left Atrium

Question 18

What are the 5 thrombi that we are most likely to encounter in veterinary medicine?

Answer 18

1. mural thrombus
2. pulmonary thrombus
3. verminous thrombus
4. saddle thrombus
5. vena cava thrombus

Question 19

Where is a mural thrombus located?

Answer 19

Heart Endothelium

Question 20

Where is a Pulmonary Thrombus located?

Answer 20

Pulmonary Artery…duh!

Question 21

Pulmonary thrombosis is most common seen in dogs. What are 2 predisposing conditions to pulmonary thrombosis in canines?

Answer 21

1. severe renal glomerular disease

2. severe heartworm disease

Question 22

Severe renal glomerular disease results is a protein losing nephropathy, causing proteinuria. What anticoagulant protein is significantly lost in this condition?

Answer 22

Antithrombin III - a MAJOR inhibitor of thrombin

Antithrombin III allows the blood to remain more fluid-like.

Question 23

What parasite is the most likely cause of Verminous Thrombus in Horses?

Answer 23

Strongylus vulgaris infection

Question 24

What are the main arteries that are likely to develop verminous thrombus in horses?

Answer 24

Cecal/Colonic as.

Cranial Mesenteric a.

Question 25

If the cecal/colonic as. develop verminous thrombus in Strongylus vulgaris infections, what are the resulting consequences?

Answer 25

Ischemic damage to the intestine --> infarction --> death

Question 26

Cats with Hypertrophic Cardiomyopathy are likely to develop a thrombus in the Left Atrium. This can cause Saddle Thrombus. Where is Saddle Thrombus located and what are the clinical signs?

Answer 26

Location: trifurcation of the abdominal aorta CS: acute onset of Left-Sided congestive heart failure, respiratory distress, pelvic paralysis

Question 27

What is an Embolus?

Answer 27

Any type of intravascular particle that travels through circulation distal to the site of origin

Question 28

What is the mechanism of development for vena cava thrombus in cattle?

Answer 28

Grain overload --> ruminal acidosis --> rumen mucosal damage --> ruminal bacteria are able to reach circulation via the portal v. --> hepatic abscess close to the Caudal Vena Cava --> vena cava thrombus

Question 29

What are the outcomes of thrombi?

Answer 29

1. lysis 2. propagation 3. embolization 4. organization/recanalization

Question 30

You are working Emergency rotation when a 3 year old pitbull terrier is brought in presenting with: acute onset of neurological disease and severe pain and dies shortly after. You get permission from the owner to perform a necropsy and find areas of necrosis in the spinal cord. You suspect spinal cord infarcts. What type of embolism is present and what are the resulting consequences?

Answer 30

Obliterating emboli made of fibrinocartilage --> ischemia myelomalacia --> hemorrhage and necrosis --> death

Question 31

Histologically, if you see adipose cells and haematopoetic cell precursors you have a...

Answer 31

Fat Embolism

Question 32

Fat Embolisms are common complications of...

Answer 32

bone fracture fragments that reach systemic circulation causing pulmonary embolism

Question 33

Upon performance of a cattle necropsy, you find a friable, patent material localized and attached to the Right Tricuspid valve. At the pulmonary artery you find a septic embolism and development of severe pulmonary abscess. What caused the death of this cow?

Answer 33

bacterial valvular endocarditis of the right atrioventricular valve **Chronic, suppurative conditions --> inflammation --> bacteremia --> bacteria localize in the heart valves --> septic thrombi attach to the valves --> pieces break off and septic emboli get stuck in the pulmonary a. --> severe pulmonary abscess

Question 34

Histophilus someone can cause neurological diseases, arthritis, pneumonia, myocarditis, and vasculitis. Which of these leads to endothelial damage, predisposing the vasculature to thrombi formation?

Answer 34

Vasculitis --> endothelial damage --> predisposing the vasculature to thrombi formation

Question 35

What is the name of the condition from Histophilus somni infection that results in thrombi formation in the brain?

Answer 35

Thrombotic meningoencephalitis (TME)

Question 36

DIC is a very important condition that veterinarians must know! What is the ultimate result of DIC and what causes it?

Answer 36

The Result: DEATH! DIC is fatal! Present in many diseases --> Endothelial damage --> WIDESPREAD COAGULATION CASCADE --> fibrin-thrombi EVERYWHERE! --> systemic hypoxia --> multi-organ failure --> death

Question 37

The Fibrin-Thrombi are stained by what?

Answer 37

PTAH Stain

Question 38

What is an Infarct?

Answer 38

localized ischemic/necrosis hypoxic injury caused by occlusion of an artery/vein