hemostasis practical

what tests/laboratory evaluation are used to evaluate primary hemostasis?

platelet count

platelet microscopic features

mucosal bleeding time

how can we evaluate the number of platelets an animal has?

platelet count

how do we evaluate the function of an animal's platelets?

mucosal bleeding time test

what laboratory tests/evaluations do we use to evaluate secondary hemostasis?

activated platelet thromboplastin time- intrinsic and common pathways

prothrombin time- extrinsic and common pathways

thrombin time- terminal common pathway

fibrinogen concentration

what is the activated partial thromboplastin time used to evaluate?

intrinsic and common pathways (factors XII, XI, IX, VIII, X, V, II, and FIB)

what is the prothrombin time test used to evaluate?

extrinsic and common pathways (factors III, Vii, X, V, II, and FIB)

what is the thrombin time test used to evaluate?

the terminal common pathway (the quantity and quality of fibrinogen)

what test do we use in the lab to evaluate the clotting dissolution?

FDP (D-dimers)

what does the platelet count give us information about?

if the patient has thrombocytopenia or thrombocytosis

how do we perform a platelet count?

it can be either manual or automatic

manual: we do a blood smear using a sample with EDTA. we count the number of platelets per field, and then multiply this by 15,000.

if we perform a platelet count and the number is lower than the normal range for that species, we call this...

thrombocytopenia

if we perform a platelet count and the number is higher than the normal range for that species, we call this...

thrombocytosis

which is more common to see, thrombocytosis or thrombocytopenia?

thrombocytopenia

what are possible etiologies behind thrombocytopenia?

congenital (breed related)

increased platelet use: DIC, hemangiosarcoma

increased platelet destruction: immunomediated, infectious

low platelet production: BM disease, chemotherapy, FIV, FeLV, NSAIDs

if an animal has moderate thrombocytopenia (40-100 x10^3), what do we expect clinically?

possible bleeding

if a patient is spontaneously bleeding, what do we expect to see in their platelet count?

severe thrombocytopenia (less than 40 x10^3)

which is more reliable for counting the platelets in a blood sample- manual or automatic (with a machine)?

manual, using a blood smear

the automatic platelet counting machine is not very reliable

what are the possible etiologies behind thrombocytosis?

bone marrow disease

iron deficiency anemia

nephrotic syndrome

myeloidal metaplasia

trauma

FeLV, FIV

chronic inflammatory disease

neoplasia

aggregations of platelets are common in what species?

this causes what type of result in a platelet count?

cats; pseudothrombocytopenia

what is the best way for us to determine the platelet function (how well the platelets are working) in an animal?

performing a mucosal bleeding time test.

for this, we make an incisions on the mucosa of the upper lip (in small animals) or of the vagina (in cattle) and measure the amount of time it takes for it to stop bleeding.

what is the mucosal bleeding time?

it is a test we use to determine the functionality of the platelets.

for this, we make an incisions on the mucosa of the upper lip (in small animals) or of the vagina (in cattle) and measure the amount of time it takes for it to stop bleeding.

if the time is higher than normal, this indicates vascular abnormalities, lack of platelets, or defects of platelet function

if we test the mucosal bleeding time in a dog and it is 7 minutes, what do we predict?

this is too high. the normal range for dogs is under 4 minutes.

this indicates vascular abnormalities, lack of platelets, or defects of platelet function

what is the normal mucosal bleeding time of a horse?

10-14.5 minutes

what is the normal mucosal bleeding time of a dog?

less than 4 minutes

what is the normal mucosal bleeding time of a cat?

1-2.5 minutes

how do we determine the platelet function automatically (not using the mucosal bleeding time test)?

we have a machine that does this automatically. it stimulates capillary flow conditions, and counts the time needed for the platelets to tap the capillary hole in a membrane coated with collagen/epinephrine or collagen/ADP.

this allows us to evaluate platelet aggregations and adhesion to detect platelet disorders.

prothrombin time (PT) evaluates what pathways?

extrinsic (VII) and common (X, V, II, I)

if there is a high concentration of fibrin degradation products, this can indicate what etiologies?

DIC

intoxication by a vitamin K agonist

hepatic disease

hypofibrinogenemia can be caused by...

DIC

advanced liver disease

a decreased antithrombin III indicates....

DIC

severe hepatopathy

protein loss nephropathy

enteropathy

after laboratory tests, we see that an animal has a LOW platelet count and a high mucosal bleeding time. This indicates:

thrombocytopenia

after laboratory tests, we see that an animal has a HIGH prothrombin time and a high activated partial thromboplastin time. This indicates:

hepatopathy

an animal who has been intoxicated by a rodenticide will show what abnormalities in their lab results?

VERY high prothrombin time (PT) and activated partial thromboplastin time (APTT)

after laboratory tests, we notice these results:

low platelet count

high mucosal bleeding time

high prothrombin time

high activated partial thromboplastin time

low fibrinogen

what do we think this animal has?

DIC

an animal with Hemophilia A or B will have what abnormality in their laboratory results?

high Activated partial thromboplastin time (APTT)

the FIB (fibrinogen) evaluation helps us to evaluate what?

heparin in the lbood

hepatopathies (low FIB)

DIC (low FIB)

what are the clinical differences between a primary hemostasis disorder and a secondary hemostasis disorder?

primary: petechia, ecchymosis, multiple hemorrhage, superficial mucosal bleeding, longer bleeding after venipuncture and incisions

seconday: hematomas, only 1 bleeding point, cavitary bleeding, delayed bleeding in wounds

if an animal presents to us with petechia, ecchymosis, and superficial mucosal bleeding, do we suspect a problem with primary or secondary hemostasia?

primary

an animal with a problem with secondary hemostasia will have these clinical signs:

hematomas

one bleeding point

cavitary bleeding

delayed bleeding in wounds

what are possible causes of DIC?

neoplasia

trauma

sepsis

endotoxemia

metritis

pancreatitis

acidosis

ETC (there are MANY)

explain the pathophysiology of DIC

1. initial cause

2. increased inflam. mediators and tissue factor

3. excessive clot formation

4. thrombosis, decreased platelets, plasmin activation

the thrombosis causes hypoxia and tissue damage, which causes multiorganic failure, as well as the breakdown of RBCs, which leads to anemia.

the decreased platelets and clotting factors and plasmin activated leads to bleeding

so at the same time, there is thrombosis and bleeding, causing damage to many organs in the body