Hematology Flashcards
What is MCV?
Mean Corpuscular Volume
- The mean volume of a group of erythrocytes
- Anemia may be normocytic, macrocytic, or microcytic
What is MCH?
Mean Corpuscular Hemoglobin
- The mean weight of Hb contained in an average RBC
What are polychromatophils?
Immature RBC
What is MCHC?
Mean Corpuscular Hemoglobin Concentration
- The concentration of Hb in an average RBC
- Normal MCHC = normochromic anemia
- Low MCHC = hypochromic anemia = low iron levels
What are Howell Jolly bodies?
Nuclear remnants
What can acanthocytes indicate?
Liver disease
What do echinocytes indicate?
- Kidney failure
- Snakebites
What do schistocytes indicate?
- DIC
- Uremic syndromes
What are Heinz bodies?
Precipitates of oxidized Hb
What is Mycoplasma hemofelis?
- Hemobartonella felis
- Bacteria
- Results in regenerative anemia
What is Hemobartonella canis?
- Bacteria
- Occurs rarely, and only in the immunosuppressed
What is Cytauxzoon Felis?
- Protozoal
- Intracellular
- Cats
- Causes non regenerative anemia
What is babesia?
- Tick borne disease
- Causes intravascular hemolysis
What is the best indicator of effectiveness or bone marrow activity?
- Reticulocyte count
What reticulocytes are counted in the dog and cat?
- Cats: only aggregate
- Dogs: all forms
How much ATP is produced in aerobic metabolism?
- 38 ATP molecules from a single glucose molecule
How much ATP is produced in anaerobic metabolism?
- 2 ATP molecules from a single glucose molecule
What are some causes of secondary failure of EPO?
- Hypothyroidism
- Hypoadrenocorticism
- Neoplasia
- Chronic inflammatory disease
What is the oxidizing component in onions?
n-propyl disulfide
Why can cats show Heinz bodies without anemia?
Cats are more prone to HB formation, but also more forgiving towards the RBC containing HB, allowing longer survival
DM or HL in cats can lead to the development of what?
Hypophosphatemia, resulting in fragile membranes and hemolysis
Methemoglobinemia occurs when….?
When ferrous iron (Fe2+) undergoes oxidation to ferric iron (Fe3+) which cannot bind oxygen and does not contribute to oxygen carrying capacity
How long do neutrophils live in circulation?
- About 10 hours
- Bone marrow stores 5 day supply
Hypersegmentation of neutrophils can be seen in what 5 states?
- Age related change in neut
- Prolonged exposure to EDTA
- Glucocorticoids
- Hyperadrenocorticism
- Chronic infection
Eosinophils
- Essential for reduction of local allergic and anaphylactic reactions because granules contain anti inflammatory substances
- Release of histamine from mast cells attracts them to the area of allergen
- Minimal phagocytic, bactericidal function - their phagocytosis is very effective against protozoa and some parasitic worms
Basophils
- Rare
- Granules contain histamine and heparin, making them effective at roles in allergic or hypersensitive reactions
Which WBC stays in the circulation the longest?
Monocytes
Which WBC lacks phagocytic capability?
Lymphocytes
What are the 3 types of lymphocytes?
- T cells
- B cells
- Natural killer (NK)
What are two possible reason to have low lymphocytes?
- Chylous effusion
- Lymphosarcoma
High does of glucocorticoids can cause a mild __
lymphopenia
Felines have a physiologic ____ from excitement
lymphocytosis
What does a left shift indicate?
It is a sign of inflammation or infection as the body increases neutrophil release in response to injury
What does a stress leukogram consist of?
- Neutrophilia
- Lymphopenia
- Eosinopenia
- Potentially monocytosis
- Occurs mostly in dogs
- ‘stress’ denotes increased cortisol release from adrenals in systemic illness etc
Where do platelets live?
- Most live in circulation but the rest are stored in the spleen
What can platelets release?
- Endothelial growth factor
How long do platelets live?
3-7 days
What can cats do with platelets?
Increase their platelets when excited
Initiation of the extrinsic pathway is usually mediated by__?
Tissue factor/Factor III via thromboplastin
Which factor triggers the common pathway?
X
Where are all the factors (except for one) produced?
- The liver
- But not F VIII
Which factor is required for most reactions?
F IV (Calcium), which is why calcium chelators such as citrate and EDTA are used for blood collection
What is responsible for the dissolution of a fibrin clot?
Plasmin, a cleaving enzyme
Plasmin exists in circulation as ___?
The proenzyme plasminogen
What activate plasminogen?
- Tissue-type plasminogen activator (t-PA)
- Urokinase-type plasminogen activator (u-Pa)
Thrombin and plasmin are OPPOSING enzymes
- Thrombin coagulates
- Plasmin dissolves
What serves as the initiator for coagulation?
Tissue factor expressed by cells located outside the vasculature
At what platelet level can spontaneous bleeding be seen?
<30,000 - 40,000
ARF/CRF can cause what platelet reaction?
Platelet dysfunction secondary to uremia
What is the most common hereditary bleeding defect in dogs?
von Willebrand’s disease
What will coagulation tests show in vWd?
vWd is a platelet function defect, so all coagulation tests, including platelet count, will be normal. IF aPTT is prolonged, it is likely due to reduced levels of F VIII
What are the 3 different types of vWd?
- Type 1: mild to moderate dz (Dobermans). Low amount of vWF, normal multimer distribution
- Type 2: moderate to severe dz (GSP & GWP). Low amount of vWF and abnormal protein structure)
- Type 3: severe dz (CBR, Shelties, Scotties). Complete absence of vWF
Why do vWb patients often have low levels of FVIII?
F VIII bonds to vWF which then protects F VIII from rapid breakdown. A deficiency of vWf means a decrease in protection to F VIII and a reduction in their levels
What disease may exacerbate bleeding tendencies in vWb dogs?
Hypothyroidism - consider if vWd is dx in an older dog with only recent hx of bleeding
What is the ideal product to administer for vWd?
Cryoprecipitate - contains vWf, FVIII, fibrinogen, fibronectin
How can DDAVP be used in vWd?
- It may control bleeding in some (not all) Type 1 dogs
- It results in the release of body vWf stores and causes a significant increase in plasma vwF, but tachyphylaxis occurs quickly
What is Hemophilia A?
F VIII deficiency
What is Hemophilia B?
F IX deficiency
What can be used to treat Hemophilia A
Cryoprecipitate
What can be used to treat Hemophilia B
Cryosupernatant
Anticoagulant rodenticides inhibit activity of__?
Coumarins, the toxic component, inhibits activity of KO reductase
- Inhibition of this enzyme results in depletion of K2 and subsequent depletion of functional Vit K dependent coagulation factors
Describe the recycling of Vitamin K
Vit K2 is oxidized to Vit K epoxide (KO). Vit KO reductase converts KO back to K2, which recyles the limited supply of Vit K in the body
What are PIVKAs?
- Proteins induced by Vit K antagonism
- Once hepatic Vit K stores are depleted, production of functional Vit K dependent coagulation ceases and forms PIVKAs
- They are incapable of chelating Ca and therefore unable to partake in secondary hemostasis
What method of Vit K administration is most rapidly effective?
PO
Which coagulation factor will be depleted first in liver dysfunction?
F VII - shortest half life
Bilateral epistaxis often indicates what kind of cause?
Systemic
German Shepherds are predisposed to what fungal disease?
Aspergillosis
What breed is predisposed to Hemophilia A?
GSD
What breed is predisposed to Hemophilia B?
Cairn terriers, Coonhounds, St. Bernards
What initiates DIC?
- A supraphysiologic expression of TF through severe endothelial injury
- TF expression on intravascular cells stimulated by proinflammatory cytokines
- TF independent triggers do exist
What blood tube should be used for platelet counts?
EDTA
Why should heparin not be used for a platelet count?
Heparin will cause the platelets to clump
What is the normal BMBT for dogs and cats?
- Dogs <4 min
- Cats <3 min
What does ACT check?
The time it takes for a fibrin clot to form
What does the PT check?
- Assess secondary hemostasis, specifically the extrinsic and common pathway
- Normal PT does NOT rule out factor deficiencies
What does the aPTT check?
- Assesses secondary hemostasis, specifically the intrinsic and common pathway
What are FDPs?
- Fragment D and E are end products of cleavages from fibrinogen and fibrin
- Assesses patient’s fibrinolytic activity
What are D-Dimers?
- A specific plasmin mediated breakdown product of criss linked fibrin
- Assesses patient’s fibrinolytic activity
- More specific than FDPs
What does a left shift and a high neutrophil count mean?
The bone marrow is able to respond to inflammation
What does a left shift and a normal or low neutrophil count mean?
The marrow is umnable to meet increased demand
What are Dohle bodies?
- Intracytoplasmic basophilic precipitates of RNA
- In dogs = significant toxicity
- In cats = can be seen in healthy animals
What do toxic neutrophils indicate?
Indicates that circulating toxins are interfering with neutrophil development in the bone marrow as a result of increased peripheral demand
What do reactive lymphocytes indicate?
They are antigen stimulated so their presence indicates that the immune system has been engaged
What factors does Heparin inhibit?
Antithrombin
IIa
IXa
Xa
XIa
XIIa
What factors do LMWH inhibit?
Xa
What medications are direct factor Xa inhibitors?
Rivaroxaban, apixaban. They do not require antithrombin for clinical effect
