clin path exam 1

hematology

the study of blood, blood-forming organs, and blood diseases

blood-forming organs

• bone marrow

• spleen

• thymus

hematopoisis

formation and development of blood cells

hematopoiesis in the embryo

yolk sac

hematopoiesis in the fetus

liver, spleen, bone marrow, lymph nodes

hematopoiesis in neonates and juveniles

marrow of long bones

hematopoiesis in adults

marrow of flat bones, end of long bones

erythropoiesis

production of erythrocytes

myelopoiesis

production of granulocytes (neutrophils, eosinophils, basophils)

thrombopoiesis

production of platelets

lymphopoiesis

production of lymphocytes

monocytopoiesis

production of monocytes

Why are RBCs important?

needed to transport oxygen

late stage and mature RBCs __________ undergo mitosis

cannot

RBCs have a relatively __________ life span

short

cell size _________ as RBCs mature

decreases

erythrocyte lifespan is _________ days in domestic animals

70-180

primary stimulus of erythropoiesis

hypoxia

maturation from rubriblast to erythrocyte takes _____ days

3-5

purple top tube

EDTA anticoagulant

light blue top tube

sodium citrate additive

red top tube

serum tube with/without clot activator or gel

green top tube

sodium or lithium heparin with/without gel

grey top tube

sodium fluoride additive and sodium or potassium

erythrocytosis

increase in RBC count

anemia

decrease in RBC count

packed cell volume (PCV)

determined by centrifuging blood in a small tube; measures percentage of blood that is RBCs

hematocrit (HCT)

calculated by automated analyzers; based on average RBC size and numbers; RBC x MCV

mean corpuscular volume (MCV)

average volume of erythrocytes

increased MCV

macrocytosis

macrocytosis is commonly caused by:

• reticulocytosis

• FeLV infected cats

• congenital in poodles

• vitamin B12 or folic acid deficiency in giant schnauzers

• RBS agglutination

decreased MCV

microcytosis

microcytosis common causes:

• #1 CAUSE iron deficiency

• immature animals

• portosystemic venous shunts

• Asian dog breeds

mean corpuscular hemoglobin (MCH)

average weight of hemoglobin per RBC; largely ignored

mean corpuscular hemoglobin concentration (MCHC)

average concentration of RBC Hgb on a weight to volume basis; reported as %; much more widely used

causes of decreased MCH and MCHC

• reticulocytosis

• iron deficiency

anisocytosis

RBC size variation

Wright’s stain

polychromatophils

New methylene blue stain

reticulocytes

reticulocytes are NOT releases in __________

horses

appropriate reasons for nRBC release

• in response to anemia

• extramedullary hematopoiesis

• low numbers in some breeds

inappropriate reasons for nRBC release

• lead poisoning

• splenic or hepatic HSA

• IVDD

• iron or copper deficiency

• myelophthisis

• bone marrow injury

poikilocytosis

oddly shaped cells

echinocytes

caused by either cells sitting out for long duration of time, or pathologic (such as snake bite)

schistocyte

piece that has been sheared off RBC by macrophages; commonly seen in IMHA patients

spherocyte

RBCs that have passed through the spleen as a schistocyte and then closed to form this cell

elliptocytes

also called ovalocytes, NOT normal usually and can be caused by protein deficiencies, but normal in camelids

Howell jolly bodies

nuclear remnants in RBCs, more numerous in splenectomy patients

basophilic stippling

most commonly seen in ruminants; hallmark of lead poisoning; don’t carry oxygen well

mycoplasma

bacterium that lacks a cell wall; infection is epicellular; unique to individual species

anaplasma

common in cattle; intracellular parasite