BIOCHEMICAL CONSTITUENTS AS AID OF DIAIGNOSIS OF DISEASES IN DOGS
P. C. Bisoi
Professor, Department of Biochemistry
College of Veterinary Science and Animal Husbandry, Bhubaneswar.
Diagnosis of a disease is an art of precisely knowing the cause of a disease. Success of treatment of a disease depends upon the accurate diagnosis. The diagnosis is based on the history, careful clinical examination of animal, laboratory examination and co-relation and interpretation of findings. Laboratory diagnosis helps the veterinarian to arrive on any conclusion. According to a well known, diagnostician ‘A veterinarian who does not need a laboratory is uninformed and a veterinarian who is totally dependent upon the laboratory findings is inexperienced and in either case the animal is in danger.’
Serum biochemical constituents are normally the secretory or excretory products of the cell or the fraction of the dietary nutrients. These constituents always remains within a range at different physiological states of a healthy individual. An abnormality in the function of the body (or tissue) in most cases represents an abnormality of the functions of the constituting cell which are reflected in the fluids bathing them and in turn in plasma and urine. The analysis of blood and urine thus provides the veterinarian with information of great clinical importance for the diagnosis and follow-up of disease. The analysis is performed on a no. of body fluids and juices such as blood, urine, cerebrospinal fluid, bile, gastric juice, pancreatic juice etc. Amongst these because of the ease with which the samples may be obtained and the change that occur in disease, blood and urine analysis have continued to play a dominant role in clinical chemistry.
Analysis of Biochemical Constituents of blood
Proteins : Serum or plasma proteins is a very complex mixture of a variety of protein and their determination is clinically of much value in diagnosis. According to electrophoretic mobility they are broadly grouped as Albumin, a1globulin, a2-globulin, B-globulin, y-globulin and fibrinogen. The total plasma protein of dog ranges between 5.4-7.1 gm/dl.
Albumin: It is a major protein of plasma. It has many function in blood. It ranges between 2.6-3.3 g/dl. The variation in the range is helpful for diagnosis of certain diseases.
Increase: Occurrence is rare. It is found during dehydration with diminution in the water content of blood.
Decrease:
- Nephritis and Nephrosis with excessive loss of albumin in urin.
- Inadequate supply of protein as a result of impaired protein digestion and absorption in peptic ulcer, advanced B., malignancy, pancreatic disease etc.
- Impaired synthesis in chronic hepatic diseases particularly cirrhosis, infection, severe anaemia.
- Excessive catabolism as in uncontrolled diabetes mellitus, thyrotoxicosis, prolonged febrile illness.
Globulin:
It is a mixture of more than 30 different proteins.
A1 globulin : It includes a1-acid glycoprotein :
Increase: Observed in acute and chronic inflammatory diseases, cirrhosis of liver, many malignant condition.
Decrease : Hepatic disease, malnutrition, nephritic syndrome.
a1Fetoprotein : It is used as a marker of hepatic carcinoma. The porotein is not normally synthesized in adult liver. The concentration increases in hepatocellular carcinoma in adult age.
a1 antitrypsin :
Increase : Acute or chronic inflammation, malignancy, liver disease, myocardial infarction.
Decrease: Nephrotic syndrome, emphysema of lungs, juvenile cirrhosis of liver.
a2 globulin : It includes ceruloplasmin, haptoglobin, a2 macroglobulin etc.
Ceruloplasmin: It is a copper containing a2 globulin increase is observed during inflammatory process, pregnancy, malignancy and decrease is observed in wilson’s diseasse.
Haptoglobin : It is a protein which prevents excretion of hemoglobin.It’s concentration decreases in intravascular haemolysis and concentration increases during inflammatory condition.
B-globulin : It includes lipoprotein, transferrin, c-reactive protein, hemopexin etc.
Transferrin: It is a iron transporting protein. The level increases in iron deficiency anaemia and during last month of pregnancy and decreases in cirrhosis of liver, nephrotic syndrome, myocardial infarction and malignancies.
Hemopexin: It is increased during diabetes mellitus, ducheme muscular dystrophy in some malignancies and decrease in hemolytic disorders.
Gamma-globulin: It includes the antibodies which are responsibkle to give protection to the animal. The level increases during infectious diseases and decreases in some genetic diseases associated with immunoglobulin synthesis.
Fibrinogens: It is a protein involved in blood coagulation. Higher level is found in multiple myeloma, Nephrosis, hepatitis, most acute infection and decrease is observed in genetic defect in synthesis, hepatic insufficiency etc.
Blood glucose: It is the major source of energy for monogastric animals. The levels of blood glucose varies between 70-118 mg/dl. Hyperglycemia is found in condition like diabetes mellitus, endocrine disorders like hyper pituitarism, hyper adrenalism and hyper thyroidsim, intracranial diseases, asphyxia, anaesthesia etc. Hypoglycemia is observed in insulin excess, endocrine disturbance like, hypoadrenalism, hypopituitarism, hypothyroidism, and in certain physiological condition such as pregnancy, starvation, lactation etc. A glycohemoglobin i.e. Hb1AC has been reported to reflect the average blood glucose level over several weeks and shows promise of being an effective means of monitoring insulin therapy both in human and dog.
Lipids: The plasma lipids are present as complex with protein molecules, the lipoproteins. Changes in the lipid components in disease result in changes in the type, of lipoproteins present in the plasma. According to density they are of 4 types i.e., chylomicron, VLDL, LDL and HDL. Among them LDL and HDL are important clinically. Lipemia in Dogs are of relatively frequent occurance. There are 5 types of hyperlipoproteinemia are seen in human beings. Type-I hyperlipopreteinemia are found in puppy and dogs.
LDL: It contain major amount of cholesterol. Increase in level of LDL indicates that the animal is more prone of artherosclerosis and myocardial infarction. Increased level is observed in xanthoma, myxodema, coronary heart diseases, nephrotic syndrome, diabetic acidosis etc.
HDL: It involves in removal of cholesterol from peripheral tissue to liver. It is a beneficial lipoprotein fraction – Increase level of HDL is found in diabetic acidosis, glycogen storage disease and low in xanthoma, nephrotic syndrome, chronic billiary obstruction.
Cholesterol : It is a important lipid fraction of the body which act as a precursor for several body constituents. The normal concentration ranges between 135-270 mg/dl. Variation in the level is associated with several disease conditions. Increased level is observed in diabetes mellitus, nephrotic syndrome, artherosclerosis, hypothyroidism, hepatic and billiary tract disease lower concentration is found in pernicious anaema, haemolytic jaundice, hepatocellular damage, hyperthyroidism etc. Diabetic dogs showed hypercholesterolemia in association with increased HDL 1 ( 2) and LDL
(B) levels. In acute pancreatitis moderate increase in cholesterol and triglycerides were observed.
Non-protein nitrogenous substance: It includes urea, uric acid, creatinine, amino acid etc.
Urea: It is a metabolic product of protein metabolism, which is normally excreted through urine. Higher level is observed mainly in the diseases associated with kidney. Decrease is rarely observed and found in liver damage.
Creatinine: It isa excretory product of creatine. The level normally increase during kidney disease and muscular dystrophy.
Uric acid: It is a metabolic product of purine metabolisms. Any defect in synthesis and metabolism of purine causes over production of uric acid accumulation of which leads to gouty arthritis. Also increased in diseases like polycythemia, leukemia, pernicious anaemia etc.
Enzymes
Enzymes are biocatalysts which enhance the multiple reactions of cell metabolism and play a vital role in normal cellular function. Certain enzymes leak into the circulation or other extra cellular fluids only when the cells are damaged. The conc. of these enzymes in serum, urine or other fluids to an extent is related to the degree of cell damage and the no. of cells involved. Some enzymes occur in different molecular forms which differ in chemical properties but catalyse the same reaction. Different forms are localize to specific organs or tissue in different conc. Depending in their functional needs . The property of relative organ specificity of enzymes and isoenzymes is being exploited extensively for arriving at a laboratory diagnosis of diseased organs.
Amylase: It splits starch in to glucose. Salivary gland and pancreatitis secret the enzyme. Damage to glandular cells or secretory pathway of these organs may cause amylase to enter blood stream.
Increase in amylase activity is observed in acute pancreatitis, perforated peptic ulcer, intestinal obstruction. Peritonitis
Lipase: It catalyzes the hydrolysis of esters in the alpha position of TG. The enzyme synthesized in secretory cells of pancreas and appears in circulation following damage to the tissues.
Increase in lipase activity is observed in acute pancreatitis, perforated peptic ulcer, carcinoma of pancreas.
LDH: It is enzyme involved in glycolysis. It is found in most tissue but found in higher concentration in muscle, heart, liver etc.
Increase: Increase in LDH activity is found in muscular dystrophy, pernicious anaemia, liver disorder, leukemia etc.
It has 5 isoenzyme types i.e. LDH1 to LDH5. LDH1: Increase indicates heart disease. LHD4 and LDH5- Increase indicates liver diseases.
ALP: The enzyme found in many tissues but higher level is found in bone, liver, intestine and placenta etc. It has 3 isoenzyme from i.e. Hepatic form – Fast, Intestinal farm – Slowest, Osseous and placenta – medium.
Increase is observed in diseases like obstructive jaundice osteo blastic sarcoma, rickets, acute liver disease etc.
It is used as a marker of bone disease and obstructive jaundice.
ACP: It is used as a marker of metastatic prostatic carcinoma.
CPK: It is a organ specific serum enzyme. It has four isoenzyme CPK1 CPK2, CPK3 and CPK- Mt. Increase is observed in muscular dystrophy, myocardial infarction.
AST: Incases is observed in myocardial infarction, moderate increase during liver and muscle diseases; haemolytic anaemia.
ALT: Marked increase in viral hepatitis and moderate increase in cirohesis of sliver, obstructive jaundice, skeletal muscle disease and myocardial infarction.
Choline esterase: It is a important enzyme which involve in hydrolysis of acetyl choline. The level of activity increase during nephrioic syndrome, acute myocardial infarction and decrease during acute liver disease, malnutrition, acute infectious disease and organ phosphorus poisoning etc.
In addition to above enzymes there are several other enzymes which are estimated for diagnosis of some specific diseases.
These blood constituent are also helpful in ascertaining the function of various organs like liver, kidneys, pancreas etc. for example.
Liver Function: To know the function of liver the level of protein, albumin, cholesterol ester, and the enzymes like – ALP, LDH, transminase are measured.
Increase in activity of enzyme ALP, LDH and ALT are indicative of liver dysfunction. Decrease in level of cholesterol ester and level of albumin are also indicate liver dysfunction.
Kidney function: Increase in the level of creatinine and urea beyond the normal range is indicative of kidney damage.
Pancreatic function: Increase in level of amylase and lipase activity indicates dysfunction of pancreas.
The level of blood constituent also helps to know the prognosis of treatment and for follow-up of disease condition.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5118314/
https://www.pashudhanpraharee.com/laboratory-diagnosis-of-canine-and-feline-diseases/
