Veterinary Clinical Pathology Lecture Review

85 question-and-answer flashcards summarizing key principles, definitions, mechanisms, laboratory values and interpretations from the Veterinary Clinical Pathology lecture.

What does veterinary clinical pathology study?

The use of laboratory methods to aid diagnosis, differential diagnosis, prognosis and treatment follow-up through hematology, clinical chemistry, urinalysis, and other procedures.

Which three main purposes do laboratory tests serve in clinical pathology?

Diagnosis of disease, establishing differential diagnoses, and assessing prognosis/treatment follow-up.

Define hematology in clinical pathology.

The study of blood and blood-forming tissues to detect disease and guide therapy.

What is hematopoiesis?

The production, differentiation, and maturation of all blood cells.

Where does hematopoiesis occur during fetal life and after birth?

Yolk sac → liver & spleen → bone marrow; after birth mainly red marrow of flat bones.

Differentiate intramedullary and extramedullary hematopoiesis.

Intra-medullary occurs inside bone marrow; extra-medullary outside marrow (liver, spleen) causing hepatosplenomegaly.

What is the difference between red marrow and yellow marrow?

Red marrow is active in cell production; yellow marrow is fatty and inactive unless converted during severe demand.

What characterises a pluripotential stem cell?

Ability to self-renew and to differentiate into all blood cell lines under growth-factor control.

What is a multipotential progenitor (e.g. CFU-GEMM)?

A committed cell that can still become several lineages (granulocyte, erythrocyte, monocyte, megakaryocyte).

List the six morphologic stages of the erythroid series in order.

Rubriblast → Prorubricyte → Rubricyte → Metarubricyte → Reticulocyte → Mature erythrocyte.

Which erythroid precursor first shows hemoglobin and a 1:1 N:C ratio?

Rubricyte.

What is unique about reticulocyte release in horses?

Reticulocytes normally remain in marrow and are not released even during anemia.

Why must mature mammalian RBCs rely on anaerobic glycolysis?

They lack mitochondria, so ATP is generated via the Embden-Meyerhof pathway.

What is the function of the hexose monophosphate shunt in RBCs?

Generates NADPH to keep glutathione reduced; G-6-PD deficiency here causes hemolytic anemia.

Which pathway produces 2,3-DPG and how does 2,3-DPG affect oxygen transport?

Rapoport-Luebering pathway; high 2,3-DPG lowers hemoglobin’s oxygen affinity, enhancing tissue release.

Name the rate-limiting enzyme of heme synthesis and its cofactor.

δ-Aminolevulinic acid (ALA) synthase; requires pyridoxal phosphate (vitamin B6).

What are the three main actions of erythropoietin (EPO)?

Stimulates BFU-E/CFU-E proliferation, enhances hemoglobin synthesis, and promotes early reticulocyte release.

Give normal RBC lifespans for cow, horse and dog.

Cow ≈160 d, horse ≈145 d, dog ≈120 d.

Where are aged erythrocytes principally removed and by which cells?

Extravascularly by splenic, hepatic and marrow macrophages.

Into what is heme sequentially degraded within macrophages?

Heme → biliverdin → bilirubin (unconjugated).

What is the formula for Mean Corpuscular Volume (MCV)?

MCV (fL) = (PCV ÷ RBC count) × 10.

Which MCV change defines microcytic anemia?

MCV lower than the species reference interval.

Define Mean Corpuscular Hemoglobin Concentration (MCHC).

Average hemoglobin concentration in RBCs: (Hb ÷ PCV) × 100; normal ≈ 32–36 %.

What does an increased Red Cell Distribution Width (RDW) indicate?

Greater size variation (anisocytosis); heterogenous population.

State the medical definition of anemia.

An absolute decrease in PCV, Hb concentration and/or RBC count causing inadequate oxygen transport.

Which morphologic pattern is typical of iron-deficiency anemia?

Microcytic hypochromic heterogenous anemia (↓MCV, ↓MCHC, ↑RDW).

How is regenerative anemia recognized in dogs and cats?

Reticulocytosis, macrocytosis, polychromasia, anisocytosis and low M:E ratio in marrow.

What are two common causes of immune-mediated hemolytic anemia (IMHA)?

Primary auto-immune reaction and secondary to drugs, infections or neoplasia.

Presence of many spherocytes on a canine blood smear suggests what disorder?

Immune-mediated hemolytic anemia.

What do Heinz bodies signify and name two causes.

Oxidative denaturation of hemoglobin; caused by onion ingestion, acetaminophen, etc.

Differentiate relative and absolute polycythemia.

Relative: red cell mass normal but plasma volume decreased (dehydration, splenic contraction); Absolute: true increase in red cell mass—primary (polycythemia vera) or secondary (chronic hypoxia, excess EPO).

Define a ‘left shift’ in neutrophils.

Increased immature neutrophils (bands ± metamyelocytes) in blood indicating marrow response to demand.

How does a regenerative left shift differ from a degenerative one?

Regenerative: neutrophilia with mature cells > immature; good prognosis. Degenerative: normal/low count with immature > mature; poor prognosis.

What causes a ‘right shift’ of neutrophils?

Increased hypersegmented neutrophils, often from glucocorticoid effect or aging cells in circulation.

List two hallmark toxic changes in neutrophils.

Döhle bodies and cytoplasmic basophilia/vacuolation.

Which congenital anomaly causes non-segmented neutrophil nuclei?

Pelger-Huët anomaly.

Give two common causes of eosinophilia.

Parasitic infestations and allergic/hypersensitivity reactions.

Monocytosis in dogs is often associated with which hormone?

Glucocorticoids (stress or therapy).

What endogenous factor regulates platelet production?

Thrombopoietin (TPO) produced mainly by the kidneys.

Below what platelet count (×10³/µL) does spontaneous bleeding tend to occur?

Below about 25 × 10³/µL.

Differentiate essential (primary) from reactive (secondary) thrombocytosis.

Primary: myeloproliferative disorder; Secondary: response to inflammation, hemorrhage, iron deficiency, splenectomy, etc.

Define disseminated intravascular coagulation (DIC).

A syndrome of widespread intravascular clotting with secondary consumption of platelets & clotting factors leading to bleeding.

Why is serum creatinine a more specific marker of GFR than BUN?

Creatinine production is constant, not diet-dependent, not reabsorbed, and minimally secreted; BUN varies with diet, catabolism and reabsorption.

What is azotemia?

Elevation of blood urea and/or creatinine; classified as pre-renal, renal or post-renal.

Which liver enzyme is most specific for hepatocellular injury in dogs and cats?

Alanine aminotransferase (ALT).

Why is sorbitol dehydrogenase (SDH) preferred over ALT in horses and cattle?

ALT activity is low in large-animal liver whereas SDH is liver-specific and rises with hepatocellular damage.

Which two induced enzymes are most useful for detecting cholestasis in dogs?

Alkaline phosphatase (ALP) and γ-glutamyltransferase (GGT).

Creatine kinase (CK) elevations primarily indicate damage to which tissue?

Skeletal or cardiac muscle.

Distinguish unconjugated from conjugated bilirubin.

Unconjugated is water-insoluble bilirubin bound to albumin; conjugated is glucuronidated in liver, water-soluble and excreted in bile.

Match bilirubin type to jaundice class: hemolytic, hepatic, obstructive.

Hemolytic: ↑unconjugated; Hepatic: mixed increase; Obstructive: ↑↑ conjugated.

How is the albumin/globulin (A:G) ratio useful?

Helps interpret total protein changes; low A:G suggests hypoalbuminemia or hyperglobulinemia, high A:G suggests hypoglobulinemia.

Give three major causes of hypoalbuminemia.

Decreased hepatic synthesis, protein-losing nephropathy, protein-losing enteropathy (or severe exudation).

What situations commonly cause hyperglobulinemia?

Chronic antigenic stimulation, inflammation, or neoplasia of plasma cells/B-cells (e.g., multiple myeloma).

List two physiologic causes of hyperglycemia in animals.

Stress-induced corticosteroid release and excitement-induced catecholamine surge.

Name four key laboratory findings in diabetic ketoacidosis.

Hyperglycemia, ketonemia/ketonuria, metabolic acidosis, glucosuria.

In an IV glucose tolerance test, failure to return to baseline by 45 min suggests what?

Glucose intolerance—possible endocrinopathy such as hyperadrenocorticism or early diabetes.

Which two serum enzymes rise markedly in canine acute pancreatitis?

Amylase and lipase (though not reliable in cats).

List four common causes of hypercalcemia in small animals.

Malignancy (PTHrP), primary hyperparathyroidism, vitamin D toxicity, chronic renal failure in horses (or hypoadrenocorticism in dogs).

Name three disorders that produce hypocalcemia.

Milk fever, pancreatitis (fat saponification), hypoparathyroidism (also eclampsia, renal failure except horse).

Give two non-renal causes of hyperphosphatemia.

Vitamin D toxicosis and hypoparathyroidism.

Which hormones regulate extracellular sodium balance?

Antidiuretic hormone (ADH/vasopressin) and aldosterone.

List two primary causes of hypernatremia.

Pure water loss (diabetes insipidus, water deprivation) and excess salt intake or administration.

State three common causes of hypokalemia.

Vomiting/diarrhea, hyperaldosteronism, and alkalosis (insulin therapy also).

Why does vomiting of gastric contents often produce hypochloremic metabolic alkalosis?

Loss of HCl increases serum bicarbonate; chloride falls more than sodium, creating alkalosis.