Hematology Basics

List some factors within the blood that may interfere with a machine CBC

- Clots - Platelet clumps - RBC agglutination - WBC agglutination - Lipemia, hemolysis, cell swelling, improper storage Cells with altered size or shape, causes them to be identified as another cell or even not identified at all - Macroplatelets - Nucleated red blood cells - Heinz bodies - Atypical cells"

List the parameters you can check for in a routine hematology

- Hemoglobin - Hematocrit count - Red Blood cell count - Mean cell volume (MCV, average size of red blood cells) - Mean corpuscular hemoglobin (MCH) - Mean corpuscular hemoglobin concentration (MCHC) - Red cell distribution width - Reticulocyte counts / percentages / indices - Packed cell volume

Define platelets

Also called thrombocytes in non-mammalian species Some vets call mammalian platelets thrombocytes as well Thrombocytopenia = decreased platelets Thrombocytosis = increased platelets

What type of anemia would you suspect if you saw normal cells on a smear?

Could be indicative of normal function if no signs of anemia Indicative of non-regenerative anemia if no other abnormalities on smear Could also be pre-regenerative anemia if insult was recent

Define Anemia and describe the signs you would see in an animal with anemia

Decreased RBC count, too few RBC Clinical signs variable - Fatigue, exercise intolerance, blood in feces and urine, yellow eyes, pale mucus membranes - More likely to see signs in severe anemia - Caused by lack of oxygen carrying capacity from reduced cell count

Define Luekopenia

Decreased total WBC Characterized by the type of leukocyte that is decreased

Describe the basic species differences seen in the RBC response to anemia

Dogs and cats show evident reticulocyte response - Cats have aggregate reticulocytes - early reticulocytes that look like canine reticulocytes - Cats also have punctate reticulocytes - mature aggregate reticulocytes but not RBC. Can remain in blood stream up to 4 weeks after anemia has resolved Horses retain reticulocytes in bone marrow so reticulocyte response does not show on CBC Cattle and sheep only show reticulocyte response with severe anemia

Define Polycythemia and erythrocythemia

Erythrocythemia - Too many red blood cells Can be relative due to loss of plasma volume without loss of RBC (dehydration) Can be absolute due to overall increase in RBC mass or count, called Polycythemia

Describe the most common signs seen in animals with both primary and secondary hemostatic disorders

GI Bleeding - Malena (black stools) - Hematemesis (vomiting blood) - Hematochezia (rectal bleeding) Epistaxis (nosebleeds) Hemoptysis (coughing up blood) Hematuria (blood in urine)"

Explain how to interpret the red blood cell count on a routine hematology screening

General count of red blood cells present in a given unit of blood Low numbers can indicate anemia, hemolysis, hemorrhage High numbers can indicate dehydration (erythrocythemia) or a disease causing excess RBC production (polycythemia

Explain how to interpret the Mean Cell Volume (MCV) on a routine hematology screening

General indication of the size of red blood cells High MCV = large cells = macrocytic Low MCV = small cells = microcytic

Explain how to interpret the Red Cell Distribution width on a routine hematology screening

General variability in size of red blood cells. Increases indicate pathology that may result in size differences of RBC Decreases not of concern, means cells are nice and uniform

Define hematology

Hematology is the study of cause, diagnosis, treatment, and prevention of diseases related to blood

Define hemostasis and broadly describe the pathologies that can result from changes in hemostatic ability

Hemostasis - ability to stop bleeding Defective hemostasis -> hemorrhage (uncontrolled bleeding) Excessive hemostasis -> thrombotic events (clotting)"

Explain proper hematological terminology

Increased number of cells - Philia (ex: Neutrophilia, basophilia) used for granulocytes (WBC with secretory granules) only - Cytosis (ex: erythrocytosis) used for all other cell types - Basically ""philia"" if the cell name ends in -phil and ""cytosis"" if it ends in -cyte Decreased number of cells - Penia (ex: lymphopenia) Exceptions - Anemia: decreased number of red blood cells - Leukemia: Cancer of blood cells

Define Leukocytosis

Increased total WBC Characterized by which type of WBC is increased

What type of anemia would you suspect if you saw large, normal-colored cells on a smear?

Large, normal cells = Macrocytic Normochromic - FeLV infection - Myeloproliferative disease - Common normal finding in poodles - Cobalt deficiency in ruminants - Artifacts from sample mishandling

What type of anemia would you suspect if you saw large, pale cells on a smear?

Large, pale cells = Macrocytic Hypochromic Indicative of regenerative anemia

Patterns of WBC Anomaly: Describe the WBC patterns you would see in a patient with leukemia

Marked increase in one leukocyte type Acute leukemia = presence of blasts

Describe the basic species differences in WBC characteristics

Neutrophil is the dominant cell type in healthy dogs, cat, horses, and camelids Lymphocyte is the dominant cell type in healthy cattle and rodents Rabbit neutrophils have shiny pink granules, look like an eosinophil Reptiles and amphibians have an additional leukocyte, the azurophil Changes in leukograms less substantial and less indicative in horses, cattle, sheep

Patterns of WBC Anomaly: Describe the WBC patterns you would see following acute inflammation

Neutrophilia Left shift Toxic change Lymphopenia

List some species-specific differences regarding platelets

Overlap in size between RBC and platelets can result in machines overcounting platelets in goats Same reason can result in machines undercounting platelets in cats

Explain how to interpret the Packed Cell Volume on a routine hematology screening

Percentage of red blood cells in a given volume of blood Manual technique, centrifuge of whole anti-coagulated blood Read as a percentage of a column Used to gauge general count of red blood cells as a way to detect anemia

Outline the hemostatic process

Primary hemostasis - Platelets detect proteins within damaged endothelial lining, clump together to form a platelet plug Secondary hemostasis - Fibrin mesh forms around plug, stabilizing it Tertiary hemostasis - Hours to days after plug forms, endothelial heals - Clot is broken down - Normal vascular flow resumes"

Describe the basic characteristics and lifespan of red blood cells in different species

Produced in bone marrow Half-life varies by species - Dog: 110 days - Cat: 70 days - Cattle: 160 days - Horse: 145 days Nucleated in birds, reptiles, amphibians, fish - Platelet is nucleated too - RBC/Platelets cannot be counted by machine since nucleated RBC looks like other cells

Explain the differences between regenerative and non-regenerative anemia

Regenerative - Low RBC but high reticulocyte count. - Reticulocytes are immature red blood cells and will eventually become RBC - The body is responding correctly and trying to replace lost RBC. - Usually happens 3-5 days after initial insult - Appear as very large RBC on a blood smear Non-regenerative Anemia - Few or no reticulocytes even a few days after onset of anemia - Bone marrow is unable to replace lost RBC for some reason Pre-regenerative Anemia - Body response is pending but not apparent. - It takes a few days for reticulocytes to show up on a CBC, possible that injury causing anemia was very recent

Patterns of WBC Anomaly: Describe the WBC patterns you would see following a chronic stress / steroid response

Response to glucocorticoids or chronic stress Mature neutrophilia Lymphopenia Monocytosis Eosinopenia

Explain how to interpret the reticulocyte count on a routine hematology screening

Reticulocytes are immature red blood cells Mature in the bone marrow, usually not released until they are mature Presence indicates regenerative anemia - body is doing what it can to restore normal oxygen carrying capacity and is sending cells to help before they're fully ready"

Patterns of WBC Anomaly: Describe the WBC patterns you would see following an adrenaline response

Short duration of response Leukocytes in circulating pool Mature neutrophilia Lymphocytosis

What type of anemia would you suspect if you saw small, pale cells on a smear?

Small, pale cells = Microcytic Hypochromic Indicative of iron deficiency due to chronic external blood loss Could be secondary to liver disease or inflammation

Describe the basic concepts of hematological blood sample collection

Suitable samples - Clotted samples not suitable for analysis - Plastic container is gold standard, glass may have effects on sample Reduce Artefact - Use proper amount of blood for tube (do not overfill or underfill) - Mix gently but immediately after collection - Gently pour blood into side of tube, do not aggressively squirt into the bottom - Perform clean venepuncture - Always use sterile equipment - Make sure plasma is separated and frozen immediately if sending externally

Describe the most common signs seen with secondary hemostatic disorders

Usually apparent after a small delay since fibrin clot takes time to form Appears as a failure to fully clot Large bleeds into tissues, joints, body cavities, tracts

Describe the most common signs seen with primary hemostatic disorders

Usually apparent immediately after trauma when injury doesn't clot Capillary bleeding on the skin, ears, mucosa Often manifests as petechia

Patterns of WBC Anomaly: Describe the WBC patterns you would see following established (chronic) inflammation

When ""normal findings"" are inappropriate - when you would expect an animal to be stressed but see no evidence of astress leukogram Means it is likely the stress leukogram is canceling out the actual leukogram changes Changes are usually mild

Patterns of WBC Anomaly: Describe the "absent stress" leukogram

When ""normal findings"" are inappropriate - when you would expect an animal to be stressed but see no evidence of astress leukogram Means it is likely the stress leukogram is canceling out the actual leukogram changes Changes are usually mild"

Name and describe the three parts of a blood smear

Base or head - Not usually relevant for clinical investigation Monolayer - Allows us to look at RBC and platelets Feathered edge - More likely to see platelet clumps, atypical cells

State the classifications of anemia

Cell Size - Macrocytic: large RBC - Normocytic: normal RBC - Microcytic: small RBC Color - Normochromic: normal color - Hypochromic: pale, lack of color

Recognize the basic diagnostic approach to changes in hematology and hemostasis

Characterize - Which cells are effected? - What aspect has changed? Count, color, size? Consider holistically - How long has it been present? - What could be causing this change? - Could there be other factors influencing these results? - Are other tests helpful or necessary in this case? - What is ""normal"" for this species / breed / age - What is ""normal"" for this specific organism?

List some species and breed-specific idiosyncrasies to be aware of regarding anemia

Cobalt deficiency can cause Macrocytic Normochromic RBC in ruminants Some poodles have Macrocytic Normochromic RBC naturally without showing any other signs of anemia