ROLE OF BLOOD TEST (CBC) IN ANIMAL DISEASE DIAGNOSIS
Post no-616 Dt-25/03/2018
Compiled & shared by-DR RAJESH KUMAR SINGH, JAMSHEDPUR, JHARKHAND
9431309542,rajeshsinghvet@gmail.com
A complete blood count is a count of the total number of cells in a given amount of blood, including the red and white blood cells; often referred to as a CBC, it is one of the most common tests done to check for abnormalities of the blood.
Whether it is a human, dog, cat, or even bird or ferret, when sick, their doctors typically draw a blood sample and perform some tests to help determine a diagnosis. These tests are generally one of two types. The first type is the complete blood count (CBC), which determines the number and types of blood cells present. The science concerned with this cellular portion of the blood is called hematology. The second type of test is a blood chemistry panel that measures the quantities of various electrolytes, enzymes, or chemical compounds in the liquid portion of the sample. Sometimes these tests yield little information about the case, but more typically, they are the fastest and best diagnostic tool available to the doctor.
In hematology, CBC (complete blood count) is a medical analysis for assessing the content of hemoglobin in the red blood, the number of red blood cells, a color indicator, the number of white blood cells, platelets. Clinical analysis of blood allows us to consider leukocyte counts and erythrocyte sedimentation rate (ESR).
CBC VALUES—-
Blood work is a very important diagnostic tool that provides a significant amount of information about your pet’s health. A complete blood count (CBC) is a blood test used to measure and evaluate cells that circulate in the blood. The test includes an actual counting of red and white blood cells as well as an analysis of cells viewed on a blood smear. A CBC may be useful as a screening test for underlying infection, anemia and illness.
Sometimes, the CBC can help determine the underlying cause of an anemia or infection. Drugs that affect the bone marrow change the CBC. Certain types of cancers, especially leukemia, may be evident on a blood smear. Blood parasites and some microorganisms are found by careful inspection of the blood cells during the CBC. In some cases, the results of the CBC will prompt we veterinarian to recommend other diagnostic tests.As we all know the ground reality of dominancy of quacks over vets in the field level in almost every states of India, This is the high time for we vets to adopt some updated technology particularly seeking help of blood test while diagnosing the animal diseases . Doing so, we can eliminate quacks from quackery and can serve livestock farmers better by providing accurate diagnosis.
With this analysis we can identify anemia, inflammatory processes, the state of the
vascular wall, a suspicion of helminthic infestations and suspicion of malignant processes in the
body. CBC is widely used in radiobiology in the diagnosis and treatment of radiation sickness.
Blood parameters —-
Currently, most of the indicators are carried out on automated hematology analyzers that
determine 5 to 24 parameters simultaneously. Of these, the main ones being the number of
leukocytes, the concentration of hemoglobin, hematocrit, number of erythrocytes, mean
erythrocyte volume, the average concentration of hemoglobin, the average content of
hemoglobin, the half-size distribution of red blood cells, platelet count, mean platelet volume etc.
• WBC (White blood cells) – The absolute content of white blood cells (normal 4.5-11 X 109
cells / L). White blood cells are responsible for recognition and neutralization of alien
components of the immune defence against viruses and bacteria and are also involved in
the removal of dead cells of the body .
• RBC (Red blood cells) – The absolute content of red blood cells (normal 4.3-5.7 X 1012 cells
/ L). Red blood cells contain haemoglobin that transports oxygen and carbon dioxide.
• HGB (Hb, hemoglobin) – The concentration of hemoglobin in whole blood (normal 13.2-
17.3 g %). Measured in moles or grams per liter or per deciliter.
• HCT (hematocrit) – Hematocrit (normal 0.39-0.49), part of the total blood volume,
attributable to blood cells . Blood by 40-45% consists of formed elements (erythrocytes,
platelets, white blood cells) and 60-65% of the plasma. Hematocrit is the ratio of corpuscles
to plasma. It is believed that the hematocrit reflects the ratio of red blood cells to the
volume of blood plasma as mostly red blood cells make up the volume of blood cells.
• PLT (platelets) – The absolute content of platelets (normal 150-400 X 109 cells / L) in blood
cells. It is involved in haemostasis.
Erythrocyte indices (MCV, MCH, MCHC): ——
• MCV – Mean volume of erythrocytes in cubic micrometers (microns) or femto litre (Fl)
(normal 80-95 Fl). In the old analysis indicate: microcytosis, normotsitoz, macrocytosis. • MCH – Mean content of hemoglobin in single erythrocytes in absolute units (normal 27-31
pg), is proportional to the relative “hemoglobin / red blood cells.” Color index of blood in
the old analysis. CPU = MCH * 0.03
• MCHC – Mean concentration of hemoglobin in erythrocytes (normal 320-370 g / L),
reflects the degree of saturation of the red blood cell hemoglobin. Reduced MCHC
observed in diseases with a violation of hemoglobin synthesis. Nevertheless, it is the most
stable haematological parameters. Any inaccuracy associated with the determination of
hemoglobin, hematocrit, MCV, leads to an increase in MCHC, so this parameter is used as an indicator of the instrument error or an error in preparing samples for study.
Platelet indices (MPV, PDW, PCT): ——-
• MPV (mean platelet volume) – The average volume of platelets (normal 10.7 PL).
• PDW – The relative width of the distribution of platelets in volume index of the
heterogeneity of platelets.
• PCT (platelet crit) – Thrombo crit (normal 0.108-0.282), the proportion (%) of whole blood
occupied by platelets.
Erythrocyte indices: ——-
• RBC / HCT – Average volume of red blood cells .
• HGB / RBC – The average content of hemoglobin in erythrocytes .
• HGB / HCT – The average concentration of hemoglobin in erythrocytes .
• RDW – Red cell Distribution Width – the distribution width of red blood cells “so-called”
red cell anisocytosis “- an indicator of heterogeneity of red blood cells , calculated as the
coefficient of variation of the average volume of red blood cells.
• RDW-SD – The relative distribution width of red blood cells by volume, standard deviation
• RDW-CV – The relative distribution width of red blood cells by volume, coefficient of
variation .
• P-LCR – Ratio of large platelets .
• ESR (erythrocyte sedimentation rate) – A nonspecific indicator of a pathological condition
of the body.
Hemoglobin ——
Hemoglobin (Hb, Hgb) in the blood, is the main component of red blood cells that
carries oxygen to organs and tissues. It is measured in moles or grams per liter or per deciliter.
His determination has not only diagnostic but also prognostic significance, as the pathological
conditions that lead to a decrease in hemoglobin, leading to oxygen starvation of tissues.
Increasing hemoglobin seen with:
• Primary and secondary erythremia
• Dehydration (spurious effect due to haemo-concentration);
• Excessive smoking (the formation of functionally inactive NSO).
Reduced hemoglobin revealed by:
• Anemia;
• Hyperhydration (spurious effect due to hemo-dilution – “dilution” of blood, increased
plasma volume relative to total corpuscles)
.
Anemia ——-
Anemia is defined as subnormal hemoglobin level two standard deviations below the
normal for the age and sex of the patient. From the CBC report, one can classify anemia as
microcytic, normocytic or macrocytic if the MCV is low, normal or high, respectively. Common etiologies of these anemias are as follows:
Microcytic:
• Fe deficiency
• Thalassemias
• Some patients with anemia of chronic disorder of inflammation
Normocytic:
• Anemia of chronic disorder
• Anemia of renal failure
• Anemia due to endocrine disorders
Macrocytic:
• B12 deficiency
• Folate deficiency
• Preleukmias
• Some cases of hypothyoidism
• Hemolytic anemias (because of high reticulocyte count)
RDW is a very useful measure in the assessment of anemia. Combined with red cell indices,
it can narrow down the diagnostic possibilities. For example, a patient with microcytic anemia
and high RDW is very likely to have iron deficiency. If the RDW is normal thalassemia become
much more likely
Erythrocytes ——
Erythrocytes (E) in the blood – Red blood cells that are involved in the transport of oxygen in the tissue and maintain body processes of biological oxidation.
Increase (Erythrocytosis, polycythemia), red blood cell count is at:
• Neoplasms ;
• Polycystic kidney disease ;
• Edema renal pelvis;
• Effects of corticosteroids ;
• Disease of Cushing’s syndrome ; • Treatment with steroids
A small relative increase in the number of red blood cells may be associated with thickening of blood due to burns, diarrhoea, receiving diuretics.
Decrease (Erythrocytopenia) of red blood cells observed at:
• Blood loss;
• Anemia;
• Pregnancy;
• Reducing the intensity of formation of red blood cells in the bone marrow; • Accelerated destruction of red blood cells;
• Hyperhydration.
Leukocytes ——–
Leukocytes (L) is the blood cells produced in bone marrow and lymph nodes. Distinguish 5 types of leukocytes: granulocytes (neutrophils, eosinophils, basophils), agranulocytes (monocytes and lymphocytes). The main function of white blood cells is to protect the body from foreign antigens (including microorganisms, tumor cells, the effect are manifested in the direction of cell transplant).
Increased (Leukocytosis) is at:
• Acute inflammatory processes;
• Purulent processes, sepsis;
• Many infectious diseases of viral, bacterial, fungal and other etiologies; • Malignancies;
• Tissue injuries;
• Myocardial infarction;
• In pregnancy (last trimester);
• After calf hood/childbirth – a period of feeding the udder/breast milk; • After strenuous exercise (physiological leukocytosis).
To decrease (Leukopenia) leads to:
• Aplasia or hypoplasia of the bone marrow;
• Effects of ionizing radiation, radiation sickness; • Typhoid fever;
• Viral disease;
• Anaphylactic shock;
• Addison’s disease – Biermer;
• Collagen/rheumatic diseases;
• Under the influence of certain drugs (sulfonamides and some antibiotics, non-steroidal anti-
inflammatory drugs, thyreostatics, antiepileptic drugs, antispasmodic oral drugs);
• Damage to bone marrow chemicals, drugs;
• Hypersplenism (primary, secondary); • Acute leukemia;
• Myelofibrosis;
• Myelodysplastic syndromes; • Plasmacytoma;
• Metastatic tumors in bone marrow; • Pernicious anemia;
• Typhoid and paratyphoid fever;
Increased numbers of various cell types are associated with the following conditions: —
Neutrophilia: ——
• Acute infections by bacterial infection
• Inflammation
• Acute hemorrhage
• Acute hemolysis
• Chronic granulocytic leukemia • Malignancy
• Medications (steroids, lithium) • Vigorous exercise
Lymphocytosis: ——
• Viral infections
• Toxoplasmosis
• Pertussis (whooping cough)
• Chronic lymphocytic leukemia
Monocytosis: ——
• Infections like TB, Sub-acute bacterial endocarditis • Malignancy
• Inflammatory bowel disease
Eosinophilia: ——-
• Allergic disorders
• Parasitic infestations
• Malignancy (Hodgkin’s disease)
• Myeloproliferative disorders
Decrease in various cell types can be associated with the following disorders:
Neutropenia: —–
• Certain bacterial infections like Brucellosis, Typhoid • Viral infections
• Medications like chemotherapy, anti-arthritis medications • Aplastic anemia
• B12 and Folic acid deficiency
• Sequestration due to splenomegaly
Lymphopenia: —–
• Viral infections (HIV) • Steroids
• Radiation, chemotherapy
Wbc ——-
Wbc (Leukogram) is the percentage of different types of white blood cells, determined by counting them in a stained blood smear under a microscope.
Color index —-
Color index (CP) is the degree of saturation of erythrocyte verses hemoglobin:
• 0.90-1.10 – normal;
• Less than 0.80 – hypochromic anemia ;
• 0.80-1.05 – red cells are normochromic;
• Greater than 1.10 – hyperchromic anemia.
In pathological states observed in parallel and approximately equal decrease in both the number of red blood cells and hemoglobin.
Reducing CPU (0.50-0.70) happens when:
• Iron deficiency anemia;
• Anemia due to lead intoxication.
Increased CPU (1.10 or more) is at:
• Deficiency of vitamin B12 in the body; • Folic acid deficiency;
• Cancer;
• Polyposis of the stomach.
For a correct assessment of the color indicator is necessary to consider not only the number of red blood cells, but their volume.
ESR —–
Erythrocyte sedimentation rate (ESR) is a nonspecific indicator of a pathological
condition of the body or it is the rate of settle down of RBC at the bottom in room temperature
condition.
Increase in ESR occurs when: —-
• Infectious and inflammatory diseases; • Collagen/rheumatic diseases;
• Kidney disease, liver and endocrine disorders;
• Pregnancy, postpartum period, menstruation;
• Fractures;
• Surgery;
• Anaemia
It can grow and physiological states such as food intake (up to 25 mm / h) and pregnancy (up to 45 mm / h).
Reducing the ESR is at:
• Hyperbilirubinemia;
• Raising the level of bile acids; • Chronic circulatory failure; • Erythremia;
• Hypofibrinogenaemia
PLATELET ABNORMALITIES ——–
Platelet count may be elevated (Thrombocytosis) or decreased (Thrombocytopenia). These may result from a variety of disorders.
Thrombocytosis: —–
Reactive:
• Vigorous exercise
• Acute hemorrhage
• Infections by bacteria
• Malignancy
Autonomous:
• Chronic myeloproliferative disorders (polycthemia vera, chronic granulocytic leukemia,
early phase myelofibrosis, essential thrombocythemia)
Thrombocytopenia: ——
Decreased Marrow Production:
• Aplastic anemia
• Chemotherapy, radiation
• B12, folate deficiency
• Leukemia, Preleukemia
Increased Destruction/Sequestration
• Immune thrombocytopenia
• Disseminated intravascular coagulation • Splenomegaly
The following terms are occasionally used in reporting CBC results: ——–
Pancytopenia: When all three cell-lines are decreased. This can result from aplastic anemia,
infiltrative processes of the bone marrow like leukemia or myeloma, preleukemia and
B12 or folate deficiency Leukemoid Reaction: The CBC report resembles that seen in leukemia (acute or chronic). This
can be seen in severe infections, malignancies and severe hemolysis.
Leukoerythroblastic Reaction: The blood report shows presence of immature erythroid as well as
granulocytic cells. This is seen in infiltrative processes in the marrow which may be a
malignancy, hemolytic anemia, infections, fracture of marrow containing bones.
