Hemostasis and Hemopathology Flashcards
What is hemostasis?
The stoppage of bleeding from an injured blood vessel
What are the 3 functional components of hemostasis?
- Vascular
- Platelets (primary hemostasis) for minor breaks in vessel endothelium
- Coagulation (secondary hemostasis) for larger breaks in vessel integrity
How does the vascular component of hemostasis reduce blood flow?
Local vasoconstriction and the compression of injured vessels by blood pushed out (from the vessels) into the surrounding tissues
How does the platelet component of hemostasis reduce blood flow?
Hemostatic plugs, and releasing factors that augment vasoconstriction and initiate vessel wall repair
How does the coagulation component of hemostasis reduce blood flow?
By forming a fibrin mesh to stabilize the platelet plug; the fibrin in the blood is inactive until it is needed
What is coagulation?
A sequential cascade of enzymatic reactions
Where are the coagulation factors created?
The 12 factors are created in the liver
What factor is everywhere in the coagulation cascade?
Factor IV, calcium
How do anticoagulants work?
By binding calcium, coagulation factor IV
What factors are in the intrinsic pathway of the coagulation cascade?
12, 11, 9, and 8 Walmart system - Things don’t cost $12, they cost $11.98
What factors are in the common pathway of the coagulation cascade?
10, 1, 5, 2, and 13. Common denominators of 10 - 10 and 1, 5 and 2. If not, you’re out of luck, you’ve got 13
What factors are in the extrinsic pathway of the coagulation cascade?
3 and 7 Extras
When is the intrinsic system activated?
When endothelium is disrupted; can be by exposed collagen, PF3 (platelet factor 3) release, or endotoxin
What is an endotoxin?
The cell wall of a gram negative bacteria; an animal may start clotting with out an injury due to an endotoxin (this is called sepsis)
What is the extrinsic system initiated by?
Tissue thromboplastin (Factor III), released by injured tissues, factor VII is then activated by factor III
What is the common pathway activated by? What does it result in?
The intrinsic and/or extrinsic systems and results in the fibrin clot
What is fibrinolysis?
Dissolution of a clot
Fibrin is digested by plasmin (an enzyme), creating what?
Fibrin degradation products (FDPs)
When does plasmin formation begin?
When the coagulation cascade is initiated
On average, how many platelets should be present per oil immersion field in a normal blood smear?
10-12
What is BMBT and how is it tested?
- Buccal Mucosal Bleeding Time - Make 2 parallel incisions of equal length and depth in the buccal mucosa and blot every 30-60 seconds without touching the skin; should clot within 1-5 minutes
What are three clinical evaluations of bleeding disorders?
- Platelet estimate in blood smear
- BMBT test
- Toe Nail Bleeding Time (TNBT test)
What are the tests used to test the intrinsic pathway?
- Whole Blood Clotting Test (WBCT)
- Activated Clotting Time (ACT)
- Activated Partial Thromboplastin Time (APTT)
How is a WBCT performed?
It is a simple screening test where you place blood in a test tube and rock gently every 30-60 seconds; dog blood should clot in 2-10 minutes, horse blood should clot in 4-15 minutes
When is an ACT test not considered diagnostic?
If the blood clots within normal limits
When is an APTT test considered to be an abnormal result of this test?
If the clotting time is more than 25% longer than the control (Normal in a dog - 17-35 sec)
What test can be used to test the extrinsic pathway?
The One Stage Prothrombin Test (OSPT); results should be within 25% of the control results
What is the most common in-clinic test for extrinsic coagulation?
The OSPT
What are some other reference lab tests for coagulation?
- Fibrinogen concentration
- Fibrin Degradation Products (FDP)
- Factor assays
What are the vitamin K dependent factors?
2, 7, 9, and 10
What is the most common cause of vitamin K deficiency?
Rodenticide ingestion
What is von Willebrand’s factor needed for?
Platelet adhesion to subendothelium and stabilizing and preventing rapid clearance of factor VIII
What is the most common inherited bleeding disorder in dogs, but is rare in cats?
von Willebrand’s disease
Which breed most commonly gets von Willebrand’s disease?
Dobermans and Rottweilers
Which breeds have clotting factor defects of Factor I?
St. Bernards and Borzois
Which breed has clotting factor defects of Factor II?
Boxers
Which breeds have clotting factor defects of Factor VII?
Beagles and Malamutes
Which breeds have clotting factor defects of Factor VIII? What is this defect also known as?
- Many breeds - Hemophilia Type A
Which breeds have clotting factor defects of Factor IX? What is this defect also known as?
- Many breeds of dogs, and domestic shorthair and British shorthair cats - Hemophilia Type B
Which breed has clotting factor defects of Factor X?
Cocker Spaniels
Which breeds have clotting factor defects of Factor XI?
English Springer Spaniels, Great Pyrenees, Kerry Blue Terrier
What is disseminated intravascular coagulation (DIC)?
Complex hemostatic defect with enhanced coagulation and fibrinolysis secondary to severe systemic disease
What does DIC create?
Fibrin strands within blood vessels, increased blood pressure, which causes hemolysis
What is the prognosis for DIC?
Poor to grave; it is not a bleeding problem but a clotting problem, the animal’s blot clots so much that it eventually runs out of clotting factor
What is anisocytosis?
Variation in red blood cell size
What is poikilocytosis?
Variation in red blood cell shape
What are the 15 different kinds pf poikilocytosis?
- Spherocyte - Heniz Body (Schmauch’s Bodies) - Ghost Cell - Eccentrocyte - Acanthocyte - Echinocyte - Blister Cells - Keratocyte - Stomatocyte - Ovaloctye - Dacryocyte - Target Cells (Codocyte) - Torocyte - Bar Cells (Knizocyte) - Schistocyte
What is polychromasia?
Variation in cell color; immature RBC’s have less hemoglobin than mature cells
What does the presence of polychromasia cells indicate?
Active erythropoiesis and a regenerative response to anemia, or the body is trying to replace loses faster than it can keep up with
What is hypocromasia?
Abnormal decrease in the hemoglobin content of RBC’s most often associated with iron deficiency
Which species’ cells are especially prone to Heinz bodies? Meaning their hemoglobin can be damaged easier than other animals
Feline
Dacryocytes can occur in dogs with __________ disorders
Myeloproliferative
Target cells may also be seen as an artifact in __________ solutions
Hypertonic
What is an inclusion?
Something included inside the RBC
What species normally has Howell-Jolly bodies in up to 1% of its red blood cells?
Cats
Large numbers of basophilic-stippled RBCs along with nucleated RBCs out of proportion to the anemia suggest ______________
Lead poisoning
What are the 6 inclusions a red blood cell can have?
- Howell-Jolly Body - Pappenheimer Body (Hemosiderin) - Basophilic Stippling - Distemper Viral Inclusions - Cytauxzoon felis - Anaplasma marginale
What are the 5 artifacts that may be found in red blood cells?
- Agglutination - Stain Precipitate - Refractile Artifact - Pseudoinclusion - Rouleaux
What are the 4 leukocyte abnormalities that may be observed?
- Pelger Huet Anomlay - Hypersegmented Neutrophils - Toxic Neutrophils - Barr Bodies
What is a spherocyte?
A small spherical RBC with a reduced ratio of cell surface area to cytoplasmic volume; spherocytosis may suggest immune-mediated hemolyic anemia
What is a Heinz Body?
It consists of hemoglobin precipitated by oxidant drugs, plant toxins, or chemicals causing small projections on one side of the cell
What are some of the causes of Heinz bodies?
- Acetaminophen (cats)
- Methylene blue in urinary acidifiers and home aquariums (cats)
- Onion ingestion (dogs and cats)
- Long term prednisone use (dogs)
- Gastrointestinal disease (cats)
- Splenectomy
What is a ghost cell?
An empty cell membrane of hemolyzed RBC’s due to there being no hemoglobin present; can happen due to blood slides being prepared from hemolyzed samples
What is an eccentrocyte?
The oxidation of a red blood cell membrane making the coloration off center
What is an acanthocyte?
Aka a Spur cell or a Specualted cell; a cell that has irregular surface projections that can result in the changes in plasma lipids; can be caused by liver disease or splenic masses
What is an echinocyte?
AKA Crenated cells; they are cells with evenly spaced projections and are a common artifact of blood slide preparation, unless the patient is dehydrated
What are Blister cells?
An irregular cell due to the RBC manufactoring process; a small number is normal, but a might amount may cause an issue
What is a Keratocyte?
- A RBC with a horn life projection; a blister cell that has ruptured
What is a stomatocyte?
A heriditary problem where the linear area of central pa
What is an ovalocyte?
An oval shaped cell that maintains a concave central pallor
What is a dacryocyte?
A RBC with a tear like shape that results from the pitting function of the spleen
What is a codocyte or target cell?
Excessive cell membrane in proportion to decreased hemoglobin, which can be caused by:
- Hypochromic anemia
- Cholestasis liver disease
- Bone marrow suppression
- Post-splenectomy
What is a torocyte?
AKA punched out cell, it is generally an indication of hypochromic anemia, and may occur as an artifact on a blood smear
What is a barr cell?
AKA Knizocyte; due to the redundancy in the cell membrane and is an outfolding of the red blood cell membrane
What is a schistocyte?
A cell that has been damaged during circulation; typically an indication of DIC but can also be hemolytic anemia, congestive heart failure, glomerulonephritis, or splenic hemangiosarcoma
What is a howell-jolly body?
The nuclear remnames in RBC’s, and is common in regenerative anemia and splenectomized patients
What is a pappenheimer body?
AKA hemosiderin, is due to iron accumulation in RBC’s and can indicate abnormal erythropoiesis
What is basophilic stippling?
Degenerative changes in the cytoplasmic ribonucleaic acid and can occur with regenerative anemia
What is a distemper viral inclusion?
Coccoid like structures within the cytoplasm of the RBC larger than Howell-Jolly bodies
What is cytauxzoon felis?
A parasite that lives in the anterior of a RBC
What is anaplasma marginale?
A disease of bovines, and it lives on the margin of the cell
What is agglutination?
When blood cells clump together or bunch up to attack itself, it can be due to a disease process (autoimmune disease) or improper slide preparation
What is stain precipitate?
When a blood slide is not rinsed properly during preparation
What is refractile artifact?
When light is hitting a cell at an angle in the microscope refracting light to appear that there are holes in the cells or “bite marks” in the cell
What is pseudoinclusion?
A blue tinged cell similar in appearance to a pappenheimer body; appears like a platelet layered either on top of below an RBC
What is rouleaux?
The stacking of cells and can be seen in dogs or cats with hyperprotenemia
What is a pelger huet anomlay?
A cosmetic genetic defect of neutrophils; AKA hypo-segmented neutrophil
What are hypersegmented neutrophils?
A WBC with 5 or more lobes in a neutrophil (a normal cell has <5), usually a senescent WBC where the nucleus is being ripped apart
What are toxic neutrophils?
A WBC that may have some or all of the following changes:
- Irregularly shaped nucleus
- Basophilic cytoplasm
- Foamy cytoplasm
- Dohlie bodies
What is a Barr body?
A small projection off of nucleus within a segmented cell; an inactivated female X chromosome
