If you have an abscess, would you expect to see neutrophilia or neutropenia?
Neutrophilia
T/F: Blood loss causes thrombocytopenia
False
Gotcha, biatch!
What is the most diagnostically useful finding in dogs with immune mediated hemolytic anemia (IMHA)?
Spherocytosis
While Greyhounds generally make great blood donors, many of them carry blood-borne diseases. The most common blood-borne disease, that we see in ~85% of greyhounds, is:
Babesia canis
~85% of Greyhounds carry positive titers for Babesia canis
What might be the cause of Heinz Body Anemia in a cat?
Anything that causes oxidative damage:
- Acetaminophen
- Propylene Glycol
- Onions, Garlic
- Lymphoma, hyperthyroidism, diabetes
Just to name a few
Briefly describe the formation of a primary hemostatic plug:
Adherence, Activation, Secretion, Aggregation
Platelets adhere to subendothelium and undergo activation (including shape change), secrete their granules, and aggregate to form a platelet plug
When are increased PIVKA values seen?
Proteins Induced by Vitamin K Antagonism (PIVKA) will be increased in:
- Vitamin K antagonism/deficiency
- Human hepatocellular carcinomas
What are the two blood systems in the cat?
**AB system **and Mik system
Briefly describe how neutrophils develop toxic change:
early release
Neutrophil “toxic change” is normally due to rapid multiplication and shortened maturation time in the bone marrow, resulting in persistence of ribosomes. This accelerated production rate is common in inflammation
T/F: DIC may be caused by induction or exposure of tissue factor or other activators of coagulation
True
Disseminated Intravascular Coagulation (DIC) may be caused by induction or exposure of tissue factor or other activators of coagulation. This may be observed in cases of sepsis, tissue necrosis, neoplasia, etc.
Which factor of the coagulation cascade is required for the initiation of secondary hemostasis?
Tissue factor (Factor III)
What is the significance of decreased fibrinogen concentration?
Significance of decrease:
- Consumption due to hypercoagulation (excessive conversion of fibrinogen to fibrin)
- Decreased production by the liver
What is the most prominent feature of a feline ‘excitement’ response?
Lymphocytosis
Increased blood flow through microcirculation results in shift of leukocytes from marginated pool to the circulating pool. This can result in a 2-fold increase in leukocyte concentration. Lymphocytosis is the most prominent feature of feline excitement response
Name a few diseases that may cause a reactive thrombocytosis:
- Chronic Inflammatory Disease
- Iron deficiency anemia
- Chronic hemorrhage
- IMHA
When crossmatching: If you do not observe agglutination, is that considered a positive or negative crossmatch?
Negative Crossmatch
If there is no agglutination or hemolysis, the recipient is not likely to have a transfusion reaction from the donor’s RBCs. Go ahead and transfuse!
Which morphological abnormality is commonly seen in red blood cells 24-48 hours following rattlesnake envenomation?
Echinocytes
What is the most common blood type in cats?
Type A
>95% of all cats have Type A blood
When examining a blood smear to analyze platelet concentration, what is the minimum number of platelets you should expect per high power field (100x)?
7-10 platelets
Horses: minimum of 4-7
Increased numbers of enlarged platelets suggests active production of platelets
Microcytic anemia in domestic animals is most often associated with:
Iron deficiency
Stabilization of the platelet plug via fibrin meshwork is referred to as:
Secondary hemostasis
This usually only occurs in large defects (In small defects –> platelets only)
What does Buccal Mucosal Bleeding Time evaluate?
Adequate platelet number and function
To perform the test, make a standardized incision, blot the blood gently, and measure time for bleeding to cease.
Normal time for dogs: 1-5 mins
Normal time for cats: 1-3.5 mins
T/F: Yellow coloration of plasma may be considered normal in large animals
True
Yellow coloration of plasma may be indicative of icterus in both small animals and large animals.
However, in large animals, it may be due to carotenoid pigments in their diet (in this case, it would be considered normal)
Dogs that are only DEA ____ and/or DEA ____ are often used as “universal donors”
Dogs that are only DEA 4 [+] and/or DEA 6 [+] are often used as “universal donors”
DEA 4 and 6 are expressed in 98% of dogs. Most dogs carry the antigen and do not develop antibodies.
T/F: Cats with Type B blood have strong natural isoantibodies against Type A, which can lead to severe and lethal transfusion reactions
True
Which laboratory tests could you use to test platelet concentration and morphology (size)?
Blood smear and hematology analyzers
When testing platelet concentration in blood, collect blood in EDTA tubes (purple/lavender top). The EDTA present in the tube binds calcium ions, stopping the coagulation cascade
Which feline blood type is associated with strong isoantibodies?
Type B
Cats with Type B blood have strong natural isoantibodies against Type A, which can lead to severe and lethal transfusion reactions
Heinz bodies are inclusions within red blood cells composed of:
oxidatively denatured hemoglobin
Cats are most susceptible to Heinz body formation. It occurs with diseases such as lymphoma, hyperthyroidism, and diabetes mellitus
If an animal has immune-mediated hemolytic anemia and immune-mediated thrombocytopenia, what is the name of this syndrome?
Evan’s Syndrome
What does a PCV value tell you?
Relative quantity of RBCs to whole blood
(what % of whole blood is made up of red blood cells)
Keratocytes are unique to which disorder?
Iron deficiency anemia
Which factor drives amplification of secondary hemostasis? Which 4 factors does it affect?
**Thrombin **is the key factor that promotes amplification of 2° hemostasis.
It affects factors Va, VIIIa, VII, and XI
The presence of macroplatelets is suggestive of:
increased platelet production
If you are given a blood panel and notice a low platelet count, but all other coagulation tests are normal, what should you be thinking with regard to this patient?
Immune-mediated thrombocytopenia [ITP]
This patient’s body is attacking its own platelets!!!
Polychromasia is indicative of:
blood loss or blood destruction with subsequent regenerative response
Polychromatophilic cells are young erythrocytes that have been released early
T/F: Most cats are Mik negative
False
_Most cats are *Mik *positive_. Cats without the Mik antigen have Mik alloantibodies.
What are the two major mechanisms of thrombocytosis?
- Increased production
- Increased distribution in plasma
Animals are usually asymptomatic with regard to the increased platelet count
What are the most immunogenic blood types in dogs?
**DEA 1.1 **and DEA 1.2
DEA 1.1: ~45% of population
DEA 1.2: ~20% of population
The presence of spherocytes is suggestive of:
Immune-Mediated Hemolytic Anemia [IMHA]
Spherocytes are erythrocytes that appear small and lack central pallor
What is the major regulatory enzyme for thrombopoiesis?
Thrombopoietin
Thrombopoietin is produced in the liver and the kidney. It stimulates the production and differentiation of megakaryocytes.
T/F: Hemorrhage alone is usually the cause of significant thrombocytopenia
False
Hemorrhage alone does not usually cause significant thrombocytopenia.
Exception: acute severe hemorrhage may result in mild thrombocytopenia
Which laboratory test is most likely to be helpful in determining whether a regenerative anemia is due to extravascular hemolysis or blood loss that occured the day before?
Plasma Protein Concentration (TP)
If the anemia is due to extravascular hemolysis, then the TP should be normal. However, if the anemia is due to blood loss, the TP should be decreased
What would be the most likely cause of lymphocytosis in a dog in St. Kitts?
Ehrlichiosis
In which animal is Rouleaux formation of RBCs considered normal? What does the formation suggest in other animals?
Rouleaux formation is normal in horses.
It suggests increased globulin in small animals
1/3 of platelets are found in the _________
spleen
T/F: Increased FDPs inhibit platelet function and fibrin polymerization
True
Increased Fibrin Degradation Product (FDPs) inhibit platelet function and fibrin polymerization ONLY when FDPs are pathologically increased (e.g. DIC). It is not a ‘normal’ control mechanism
What is the significance of increased fibrinogen concentration?
An increased fibrinogen concentration can be indicative of inflammation. You may also see a relative increase with dehydration.
In a major crossmatch, what is tested from the recipient?
What is tested from the donor?
In a major crossmatch, the patient’s serum and the donor’s RBCs are tested
Increased FDP and D-dimers are commonly associated with:
Disseminated Intravascular Coagulation (DIC)
If you see a lot of Fibrin Degredation Products (FDP) and D-dimers, you know there is a high amount of fibrinolysis taking place. The usual indication is DIC.
What are the 2 major blood systems in dogs?
**DEA **and Dal
DEA = Dog Erythrocyte Antigen
Dal = a common antigen in most dogs, but is lacking in some dalmations
If a patient’s platelet count is lower than the lower reference interval (LRI), the patient has:
thrombocytopenia**
The degree of thrombocytopenia is gauged based on how much lower the platelet count is than the reference interval.
If the patient has <20,000/µL, that patient could spontaneously hemorrhage!
T/F: Splenectomy is almost always required in the pathogenesis of hemolytic anemia associated with Mycoplasma haemocanis
True
Splenectomy predisposes animals to acute infection by Mycoplasma haemocanis
If you see an increased PT in a patient, what is the significance of that finding?
Factor VII deficiency or deficiency/inhibition of common pathway factor
**Prothrombin time (PT) is a good screening test for Vitamin K deficiency because of the short t1/2of Factor VII**
T/F: Severe immune-mediated thrombocytopenia (2,000/µL) will result in a prolonged ACT.
True
Any severe thrombocytopenia less than 10,000/µL can cause slight prolongation of ACT (Activated Clotting Time)
What is the difference between -penia and -philia?
- penia = fewer (e.g. neutropenia)
- philia = more (e.g. neutrophilia)
T/F: DIC is caused by continuous activation of coagulation and fibrinogenesis
False
DIC is caused by continuous activation of coagulation and fibrinolysis
The result is thrombosis of the microvasculature and depletion of coagulation factors and platelets (ultimately a lot of bleeding)
aPTT requires ~___% deficiency of factor before prolongation is detected
aPTT requires ~70% deficiency of factor before prolongation is detected
**This is a more sensitive test than ACT**
Which test(s) would you use in the clinical setting to evaluate platelet function?
Bleeding time tests
Buccal mucosal bleeding time; cuticle (toenail) bleeding time
T/F: It is common to see an increased MCHC in a cat with an elevated reticulocyte count following acute blood loss
False
During a regenerative response following acute blood loss, Mean Corpuscular Hemoglobin Concentration [MCHC] is expected to be decreased
**The decreased MCHC is due to the presence of many reticulocytes that are still making hemoglobin**
Which laboratory test(s) would be useful in analyzing platelet production?
Bone marrow aspirate
Bone marrow aspirates (BMA) evaluate megakaryocyte number and morphology
T/F: Von Willebrand Factor is a blood glycoprotein that is important in red blood cell adhesion
False
Von Willebrand Factor is a blood glycoprotein that is important in platelet adhesion.
vWF binds to GP1b on the platelet and serves as a bridge between platelets and collagen.
A stress leukogram is characterized by:
lymphopenia, neutrophilia (not greater than 2x reference interval), eosinopenia
A stress response occurs with illness, pain, metabolic disturbances, tx with corticosteroids, corticosteroid-producing tumors
**do not confuse the neutrophilia of stress with inflammation**
What is a “left shift” and what is it indicative of?
↑ conc. of immature neutrophils; inflammation
A left shift is an increased concentration of immature neutrophils in the blood (usually band neutrophils, but may include metamyelocytes). Left shifts can occur with neutrophilia, normal concentration of neutrophils, or neutropenia.
**If a left shift occurs with neutropenia, it is a more severe inflammatory response**
Where is urea sythesized and what is the precursor molecule?
Liver, ammonia
Basophilic stippling is considered normal in which species?
ruminants
Basophilic stippling is an abnormal aggregation of ribosomes that appear as small basophilic granules. You may see it associated with very regenerative anemia in cats and dogs.
**If you see significant basophilic stippling in small animals, consider Lead Poisoning**
Which stain(s) is/are used to view Heinz bodies?
NMB or Brilliant Cresyl Blue
When stained with vital stains such as new methylene blue (NMB) or brilliant cresyl blue, Heinz bodies appear as blue structures.
If you see increased albumin in a patient, what should you be thinking immediately?
Dehydration
Spontaneous hemorrhage occurs when platelet count is:
Less than 20,000/µL
T/F: Dogs, cats, horses, and cows all release reticulocytes
False
Horses do not release reticulocytes
What platelet count would you expect to observe in a case of warfarin toxicosis?
Platelet count is usually normal
However, PT, aPTT, & ACT will be prolonged, and PIVKA will be positive
Which blood tube should be used when testing platelet concentration in blood?
EDTA (Purple/Lavender Top)
The EDTA present in the tube binds calcium ions, stopping the coagulation cascade.
If your patient presents with anemia, low serum iron, and microcytosis, what should you be thinking?
Iron Deficiency Anemia
What result would you expect to see for intrinsic tests in a case of warfarin toxicosis?
aPTT and ACT will be prolonged
ACT requires ~___% deficiency of factor before prolongation is detected
ACT requires ~95% deficiency of factor before prolongation is detected
Disseminated Intravascular Coagulation (DIC) generates fibrin strands that sever RBCs as they try to pass through a thrombus, leading to the formation of what type of cell?
schistocytes
What is the 1 coagulation test that accesses the extrinsic/common pathway?
Prothrombin Time (PT)
PT measures time for fibrin clot formation in* citrated plasma + tissue factor + Ca2+ + platelet phospholipid substitute*
PT requires ~70% deficiency of factor before prolongation is detected
How does the coagulation panel appear in the consumptive phase of DIC?
↑aPTT, ↑PT, ↑ bleeding time, ↑FDP, ↑ D-dimers
↓fibrinogen, ↓PLT, ↓AT
Which portion of a blood smear would you read to look for parasitic organisms?
Feathered edge
What are the two major end-products of fibrinolysis?
**Fibrin Degradation Products [FDPs] **and D-dimers
Give 2 examples of when you may see falsely decreased platelet concentrations on a blood analyzer:
macrothrombocytes and clumping
Pseudothrombocytopenia may occur if the platelets are too big (macrothrombocytes) or if they are clumped
T/F: Bleeding tests are useful for testing fibrin plug formation
False
Bleeding tests test the ability of platelets to form a platelet plug. They do not test fibrin plug formation
T/F: Naturally occuring alloantibodies are not present in canines
False
Natural alloantibodies can occur. If a dog is exposed to certain blood types, they may already have alloantibodies
Which feline blood type is considered a “universal donor”?
TRICK QUESTION
Cats do not have “universal donors”
All cats have naturally occurring alloantibodies. Blood type all cats prior to transfusion!
However, there are cats with Type AB blood (very rare) that are “universal recipients”
T/F: Dogs can have more than 1 blood type
True
For instance, dogs can be DEA 1.1, 4, 6 positive, etc.
T/F: von Willebrand Disease (vWD) is a platelet defect that results in decreased adhesion
False
von Willebrand Disease (vWD) is a defect in the **adhesion molecule that binds platelets during initiation of a platelet plug, **resulting in decreased platelet adhesion. It is not a defect in the platelets themselves. vWD is an inherited disorder.
Where is blood most commonly lost in the case of chronic blood loss?
Intestine
Blood loss via the intestine is most common with regard to chronic blood loss
(e.g. GI ulcer, bleeding GI tumor, blood consuming parasites)
Which blood tube would you use when collecting a sample for coagulation tests?
Sodium Citrate Tube (Blue Top)
Many drugs and chemicals that cause Heinz body formation also cause a condition characterized by decreased O2-carrying capacity, known as:
methemoglobinemia
With methemoglobinemia, iron is in a ferric state, incapable of carrying oxygen
Name the two phases of DIC.
In which of these phases do we observe massive bleeding?
Hypercoagulable phase (1st) and Consumptive phase (2nd)
Massive bleeding occurs in the consumptive phase as a result of consumption of platelets, coagulation factors, and antithrombin
T/F: Döhle Bodies are an inherited neutrophil abnormality
False
Döhle Bodies are denatured aggregates of free ribosomes associated with toxic neutrophils. Döhle bodies are an *acquired *neutrophil abnormality, not an inherited one
How would you macroscopically interpret a crossmatch? What about microscopically?
Macroscopically, you would check for hemolysis and check for agglutination.
Microscopically, you would check for agglutination under the microscope.
If there is agglutination, then the crossmatch is positive. If there is no agglutination, the crossmatch is negative.
What are the two coagulation tests that access the intrinsic/common pathway?
aPTT and ACT
Activated Partial Thromboplastin Time (aPTT) measures time for fibrin clot formation in citrated plasma
Activated Clotting Time (ACT) measures time for fibrin clot formation in non-anticoagulated whole blood
aPTT is a more sensitive test than ACT!
T/F: Ethylene glycol toxicosis is often associated with Heinz body anemia in a cat
False
Propylene glycol toxicosis is associated with Heinz body anemia in a cat.
T/F: Cats can have transfusion reactions following the first transfusion
True
An increased concentration of Howell-Jolly bodies is associated with:
regenerative anemia, splenectomy, and suppressed splenic function
Howell-Jolly bodies are nuclear remnants in erythrocytes
What are the two most antigenic blood types in the horse?
Aa and Qa
Aa and Qa are highly immunogenic and are implicated in neonatal isoerythrolysis.
There are no “universal donors” in equines
Which coagulation factors are dependent upon Vitamin K for their activity?
II, VII, IX, X
…that’s two, seven, nine, and ten if you’re not a roman numeral fan
Which cofactor is required for antithrombin to inactivate thrombin?
Heparin
Heparin allows antithrombin to bind thrombin in a 1:1 ratio to inactivated thrombin
T/F: Howell-Jolly bodies are formed as a result of oxidatively denatured hemoglobin
False
Heinz Bodies are oxidatively denatured hemoglobin
Thrombocytopenia can be the result of abnormal distribution of platelets; more specifically the sequestration of platelets in large vascular beds.
Which 3 conditions are most associated with this presentation?
splenomegaly, splenic torsion, neoplasia
Iron deficiency anemia in adult animals is *almost always *due to:
chronic blood loss
(in nursing animals, it’s almost always due to inadequate intake of iron)
Lack of a steroid response in a sick animal should trigger you to consider:
hypoadrenocorticism
Name a few situations that may cause a reactive thrombocytosis:
- Rebound from thrombocytopenia
- Post-splenectomy
- Response to some drugs (Vincristine)
- Excitement & exercise (epinephrine –> splenic contraction)
T/F: Increased Mean Platelet Volume (MPV) is suggestive of increased thrombopoiesis
True
What are the major mechanisms for thrombocytopenia?
Production, Consumption, Destruction, Sequestration, Loss
How I remember it:
_P_latelet _C_ount _D_own _S_uper _L_ow
Which species is most susceptible to copper toxicosis?
Sheep
Copper tends to be stored in the liver. Stressful events lead to the release of stored Cu, which can result in hemolytic anemia, hemoglobinemia, hemoglobinuria, and Heinz body formation
A neutrophil concentration greater than 2x the upper limit of the reference interval indicates:
inflammation
Which blood type is not always expressed in Dalmatians?
Dal
Dal is ubiquitous in non-Dalmatians, but some dalmatians lack the Dal antigen. Dalmatians are at risk for acute and delayed onset of hemolytic transfusion reactions.
An increase in the number or proportion of lymphocytes in the blood is termed:
Lymphocytosis
Magnitude and morphology is important for diagnosis. For instance, if you have a lymphocyte count that is way way over the reference interval, it’s likely that you’re dealing with lymphocytic leukemia
When crossmatching: If you observe agglutination, is that considered a positive or negative crossmatch?
Positive Crossmatch
If agglutination or hemolysis are detected, the recipient is at risk for a transfusion reaction. Do not transfuse from this donor!!
List some of the clinical features associated with thrombocytopenia
- mucosal bleeding
- petechiation
- ecchymosis
- spontaneous hemorrhage: PLT count
- +/- hemorrhagic anemia
T/F: Chediak-Higashi syndrome is an inherited neutrophil abnormality
True
What RBC morphological abnormalities are associated with canine hemangiosarcoma?
Schistocytes and acanthocytes
Briefly describe the mechanism of warfarin toxicosis:
**Warfarin toxicosis **essentially blocks the synthesis of Vitamin K (an essential compound for normal blood clotting). The result is spontaneous and uncontrolled bleeding.
Why might you get a coagulopathy in a patient with liver disease?
- Decreased Synthesis of coagulation factors
- Production of dysfunctional factors (failure to metabolize/reduce Vitamin K)
What are lymphoblasts in peripheral blood indicative of?
lymphocytic leukemia
lymphoblasts are not normal to see in peripheral blood
Which type of tube should be used for collection of a blood sample for a complete blood count?
EDTA (Purple/Lavender Top)
EDTA preserves cell morphology
In which species is neonatal isoerythrolysis most common?
Horses
(felines are the next most common - “fading kitten syndrome”)
T/F: Punctate and aggregate reticulocytes are both included in the reticulocyte count in cats
False
Aggregate reticulocytes become punctate reticulocytes. Punctate forms are not polychromatophilic with Wrights stain, and are not counted in the reticulocyte count.
T/F: Blood first appears brown when 90% of hemoglobin is changed into methemoglobin
False
Blood first appears chocolate brown at 30% methemoglobin.
90% is significant because levels that high result in death!
T/F: Anemia of Inflammatory Disease is characterized by increased iron storage
True
With inflammatory disease, the body is trying to lower serum iron levels so the iron isn’t available to organisms for their own reproduction
**You would see lower serum and storage iron in a case of chronic blood loss anemia**
Where in the body is **hepcidin **produced? What is it produced in response to?
Liver; bacteria
Hepcidin is produced in the liver in response to LPS in Gram [-] bacterial cell walls.
Hepcidin inhibits iron from leaving cells by removing and destroying ferroportin (the exclusive transporter of iron out of cells)
Hepcidin is a hepatic peptide that inhibits iron from leaving cells by removing and destroying ____________
Ferroportin
Ferroportin is the only transporter that allows iron out of cells.
T/F: A myeloid:erythroid precursor (M:E) ratio of 1:1 to 3:1 in bone marrow can be normal
True
What is the end goal of primary hemostasis?
Platelet plug
What is the end goal of secondary hemostasis?
Fibrin clot
Which test will be prolonged if your patient is lacking von Willebrand factor (vWF)?
Mucosal Bleeding Time
What is the best way to tell if a horse has a regenerative anemia?
Increased MCV
Which factor of the coagulation cascade has the shortest half-life?
Factor VII
Name the three components that contribute to coagulation efficiency:
Factor V, Ca2+, and PLT membrane
