Blood Clotting

Anna-Lisa TaylorAmy Hypnarowski

Vet Science 229Cal Poly, San Luis Obispo

Blood – “Fluid of Life”• Blood is:– Connective, liquid tissue

• General Function– Transportation of Oxygen– White blood cells used in immune system– Deliver’s nutrients to organs and tissues– Removes waste– Carries hormones– Regulates pH and iron composition of interstitial

fluids• pH must remain between 6.8-7.4 or cells will be

destroyed

– Maintains acid/base metabolism

Blood Composition

• Blood is composed of:– Red Blood Cells

(RBCs) or erythrocytes

– Platelets or thrombocytes

– White blood cells or leukocytes

– Plasma

Platelets

• A major factor in blood clotting.• Colorless, irregularly shaped cell fragments

with a sticky surface.• Made in the bone marrow.

Blood Clotting

• Blood clotting is a instantaneous response by the body to repair a torn blood vessel.

• 4 components of blood clotting:– Platelets– Clotting Factors (specialized proteins)– Fibrin (protein mesh)– Other cells (red/white blood cells)

Four Step Clotting Process -Extrinsic Pathway

1. Vascular Constriction2. “Platelet Plug”

– Platelets– Clotting Factors

3. Fibrin Mesh4. Clot Reinforcement

Step 1 – Vascular Constriction• This limits the flow of blood to the injury. • Visual signs include:– Paleness– Increased blood pressure (if the wound is large

enough)

Step 2 – Platelet PlugPlatelets

• First, platelets are activated by thrombin.– Thrombin is a specialized protein.

• Then, they bind to the exposed collagen on the broken blood vessel• Platelets can change shape to accommodate shape of the plug.

Step 2 – Platelet PlugClotting Factors

• Clotting factors are always present in the blood.

• They are activated when they pass by the site of a platelet plug.

• They attach to the plug to reinforce the seal.

• There are many different types of clotting factors.

Step 3 – Fibrin Mesh

• A “fibrin web” forms when certain clotting factors weave together to form a net.

• Acts as “glue” to hold clot together.

Step 4 – Clot Reinforcement • Clots are reinforced by red and white blood cells that pass by

the clot.• If only platelets are present, the clot is called “White

Thrombus”• If red blood cells are present, the clot is called “Red

Thrombus”

Red Thrombus

When Blood Clotting Goes Wrong• Blood clotting disorders result when blood clots too much. • Other blood clotting conditions occur when blood fails to

clot enough. • May be the result of a disease, or after trauma. – May also be the result of certain toxins and cancer cells

in the blood stream.• A clotting problem can occurs when:– Platelets don’t stick (hemorrhaging)– Thrombin levels aren’t regulated (thrombosis)– Deficiency of certain blood clotting factors (hemophilia)– Abnormal proteins interfere with clotting

(antiphospholipid syndrome)

Hemophilia in Dogs

• What is hemophilia?– Excessive or abnormal

bleeding

• How is it caused?– Deficiency of certain blood

clotting factors. – Abnormal platelet function

• How is hemophilia inherited?– Sex-linked disorder.– Females are carriers, but

typically males are the ones affected

Hemophilia in Dogs (cont.)• Common Signs:

– Excessive bleeding after trauma, or surgeries

– Prolonged bleeding after loss of baby teeth

– Bleeding under the skin (bruising)– Blood in diarrhea

• Veterinary Signs– Acute blood loss anemia (caused by

decrease in RBCs)– Unexplained sub-sutaneous masses

(bleeding under skin)– Neurological disorders (bleeding into

brain)– Respiratory distress (bleeding into

chest or lungs)– Lameness or soreness (associated

with hemorrhaging in muscles or joints)

Hemophilia in Dogs (cont.)• Treatment:

– No permanent cure• Short-Term Clinical Treatment

Options:– Administer fresh plasma, fresh

frozen plasma, cryoprecipitate (clotting factor VIII), cryosupernatant (clotting factor IX)

– Plasma has a short half-life, so it must be transfused every 8-12 hours until bleeding ceases

Plasma contains all the dissolved components of blood, including ions (K, Cl, S, etc) proteins and clotting factors

•Short-Term Home Care Options- Remove possible sources of injury- Limit breeding of positive carriers

Thrombosis • What is thrombosis?

- clotting of the blood in a blood vessel • How is it caused?

- Non-regulated activation of prothrombin to form thrombin - Failure of negative feedback loop to deactivate formation of thrombin from prothrombin - Failure of thrombin inhibitors:

1. Antithrombin III2. α-2 Macroglobulin3. Heparin Cofactor II4. α-1 Antitrypsin

Thrombosis cont.

Non-Life Threatening Effects:Vascular Thrombosis: caused

from poor injection or catheterization techniques

Life Threatening Effects:Thrombus (embolism) can

travel through bloodstream to:

• Lungs: (pulmonary embolus)• Heart: heart attack• Brain: stroke• Arteries and Veins :

Ischemia of affected tissues

Thrombosis in Cattle

Courtesy of Dr. Sameeh M. Abutarbush

Embolic Pneumonia: infection in the lungs caused by an embolus

If an aneurysm occurs in pulmonary arteries containing septic emboli, they may rupture and cause interpulmonary hemrraghing.

Signs:– Coughing– Dyspnea– Abnormal lungs sounds

Can Result in:– Epitaxis (hemorraghing from the

nose)– Hemoptysis (coughing up blood)– Death

Embolic Pneumonia in a cow with Endocarditis syndrome

Thrombosis in Cattle cont.

Treatment of Embolic Pneumonia:• Rest • Long term antibiotics• Intermittent administration of antipyretic and anti-

inflammatory drugs• Use culture and sensitivity results to decide on what

antibiotics to useRecovery:• Prognoses for recovery is guarded.• Performance is decreased.

Did You Know

A vampire bats saliva contains a chemical that keeps the blood from coagulating.

Aww so cute..

Question 1

What is the pH of the blood.a) 6.8 -7.4b) 5.0 – 6.0c) 1.25 – 2.8d) 5.9 – 6.7

Question 2

What is not a function of blood?a) Deliver’s nutrients to organs and tissuesb) Removes wastec) White blood cells transfer oxygend) Maintains acid-base metabolism

Question 3

What are platelets activated by to begin the formation of a clot?a) Prothrombinb) Thrombinc) α-2 Macroglobulind) Heparin Cofactor II

Question 4

• What are signs of hemophilia?a) Bleeding under the skinb) Dyspneac) Blood in diarrhead) A and C

Question 5

How can you treat embolic pneumonia?a) Antibioticsb) Restc) Anti-Inflammatory drugsd) All of the above

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