Veterinary Clinical Pathology PDF

VETERINARY CLINICAL PATHOLOGY ERYTHROCYTES platelets Measurement of its width has been used to estimate white blood cell counts...

VETERINARY CLINICAL PATHOLOGY ERYTHROCYTES platelets Measurement of its width has been used to estimate white blood cell counts - Microfilaria may be detected by microscopic Erythrogram examination of the plasma just above the buffy coat layer - counts of red blood cells (RBC) - RBC mass (hematocrit) Hemoglobin determination - hemoglobin concentration - RBC indices (cell size, hemoglobin content) - The most accurate direct indication of oxygen - RBC size variation (red cell distribution width or transport capacity of blood and approximately 1/3 RDW) of the PCV if erythrocytes are of normal size - reticulocyte counts (percentage or absolute) - Acid- hematin method - nucleated RBC count (per 100 WBC or absolute) - oxyhemoglobin ( Tallqvist hemoglobin scale and - RBC morphologic features, including presence of Dare chemoglobinometer) parasites. - Cyanmethemoglobin - Avian erythrocytes must be lysed and the specimen Packed cell volume ( PCV) must be centrifuged to remove free nuclei before Hb concentration - Hematocrit is the % of blood composed of erythrocytes; to separate blood is thru RBC counts centrifugation (platelets, plasma, and leukocytes - performed with a hemocytometer, have a large are trapped between red cells) degree of error; hemacytometer-derived RBC - PCV, buffy coat and plasma counts are of limited value, except in avian species. - Microhematocrit and macrohematocrit - Automatic counters, if standardized for mammalian - Red blood cell packing is species-dependent – it blood, allow for more accurate RBC counts takes longer for ruminant RBCs to pack compared - Automated counters are not well validated for to dogs, cats and horses, Therefore, the avian blood, because all nucleated cells (RBCs, microhematocrit tubes are spun for 10 minutes in WBCs, and thrombocytes) are counted ruminants versus 3 minutes in other species. - The primary value of the RBC count is that it allows determination of MCV and MCH Mean corpuscular values (MCV) - Mean Corpuscular Volume (MCV) (Hctx10)/rbc(milllions)=femtoliters(fl) Ex:pcv- 45%,rbc count- 5 million/ul 450/5.0 = 90 fl Increased in macrocytic anemias ( B12,folic acid deficiencies Reticulocytosis causes transitory increase Iron deficiency decreased MCV - Mean Corpuscular Hemoglobin(MCH) (Hb x 10)/rbc(millions)=picograms (pg) Ex. Hb-15 gm, rbc count – 5 million/ul 150/5.0=30 pg Decrease in iron deficiencies Slightly increase/normal in reticulocytosis Increase in vitro and vivo during hemolysis - Mean Corpuscular Hemoglobin(MCHC) - (Hb x 100)/Hct=grams per deciliter ( gm/dL) Ex. Hb- 15 gm/dL ,pcv- 50% 1500/50 = 30 gm/dL - Plasma color and transparency most accurate rbc indices a. Normal plasma is clear and colorless (dog and reticulocytosis and iron deficiencies decreased cat) to light yellow (horse and cow) MCHC b. Icteric plasma is yellow and clear Increase in vivo and vitro during hemolysis and c. Hemoglobinemic plasma is pink to red and clear spherocytosis d. Lipemic plasma is whitish to pink and opaque - The buffy coat zone, a white layer between the RBCs and plasma, is comprised of leukocytes and PETRACHE, N.T.  VETERINARY CLINICAL PATHOLOGY Sedimentation rate - Polychromatophils are not observed in blood from healthy horses and are rarely observed in blood - Principle: blood with anticoagulant is allowed to from anemic horses stand in perpendicular tube, erythrocyte sink - microcytosis is a normal finding in foals up to 1 year because they are heavier than plasma which they of age, and is attributable to a physiologic iron are suspended deficiency (puppies and kittens can display a similar - Normal animals- speed of erythrocytes fall is slow microcytosis between 4-8 weeks of age). and increased with anemia, inflammation and necrosis - Most applicable to dog’s blood SPECIES DIFFERENCES FOR ERYTHROCYTES Canine erythrocytes Caprine erythrocytes - large, uniform, biconcave disc with an area of central pallor - Marked poikilocytosis (especially Angora) and - Small numbers of polychromatophilic erythrocytes prominent in kids (< 3 months of age) from healthy dogs (