The focus of this article is how interpretations of laboratory data can utilize individual and population reference intervals, while taking full advantage of routine test procedures along with some of the newer laboratory tests, which can complement the ones. existing tests in the diagnosis of diseases.
Biochemistry; endocrine disease; Hematology; New tests; Reference change intervals; Reference ranges.
Types of Veterinary Diagnostics
- Clinical Chemistry
Clinical chemistry is the study of the chemical composition of a sample. Usually, the sample is the liquid portion of the blood (serum or plasma), although other bodily fluids can also be studied. Clinical chemistry tests are important in determining how well different organs (kidneys, liver, etc.) are working. They can help identify specific disorders, such as diabetes or pancreatitis. These tests can also be used to monitor how your pet responds to treatment.
The study of individual cells, their structure and origin, function (s), and death is known as cytology. Specialists in this field (pathologists) can provide your veterinarian with information about the cells in your pet’s body. Tissue samples (taken by fine needle biopsy) or fluid are collected, then slides are prepared and stained for microscopic examination to determine the types of cells present.
Pathologists are often called in to identify cancer cells or determine whether a tumour is benign or cancerous (malignant). The presence of infectious agents can also be determined. Some microorganisms can be identified (some forms of yeast have a unique appearance), but bacteria require microbiology testing for identification.
- Fluid analysis
Fluid analysis is the study of body fluids other than blood (urine, joint fluid, etc.). Body fluid analysis specialists work closely with other specialists to help provide information about an animal’s health. Generally, the fluid analysis includes checking the sample for cells and proteins. Clinical chemistry tests can also be done for certain compounds.
Haematology is the study of the cellular elements of the blood (red blood cells, white blood cells, and platelets), and how these elements change in health and disease. The most common blood test is a complete blood count (CBC). This test determines the number and types of cells circulating in the bloodstream and provides basic information about anaemia, inflammation, and clotting.
Determining the number of red blood cells, their size and shape, and their haemoglobin content (the molecule that carries oxygen) helps identify disorders such as anaemia. Counting the different types of white blood cells provides information about inflammation, which could be due to an infection or another cause. Platelets are also tested during a CBC; changes in the number or appearance of platelets can help identify blood clotting disorders.
Histology is the study of the microscopic structure (anatomy) of animal and plant tissues. Histology experts (called pathologists) examine small samples of tissue to determine whether they are normal or diseased. Pathologists have studied the causes and effects of disease and can often pinpoint the reason for the abnormal arrangement of tissues or cells. Oftentimes, small tissue samples will be sent to a pathologist if your vet suspects conditions such as cancer or other diseases that cause changes in the tissues.
Microbiology is the study of small organisms such as bacteria, viruses, fungi, and other single-celled life forms. In a veterinary laboratory, microbiologists can perform many tests to look for signs of infection. A common procedure includes first growing (culturing) and then identifying bacteria, viruses, and fungi. The bacteria can be tested to see which antibiotics should be effective in eliminating them from the body.
Some microorganisms are difficult to grow in the laboratory, and antibodies or other chemicals can be used to detect the presence of microorganisms in a sample. Samples from your pet that can be used to grow microorganisms include blood, urine, faeces, discharge from the nose or lungs, and samples taken from a wound or abscess.
Serology is the study of blood serum and other bodily fluids. Most serologic tests determine the level of antibodies (called the titer) that are present and reactive against a particular infectious organism. A high level of antibodies, or an increase in their level from one sample to another taken a few weeks later, indicates that an animal has been exposed to the microorganism and its immune system has produced antibodies against the infectious agent.
Commercial test kits are available for a wide range of serological tests. The test kits are regularly used in both internal and external laboratories to detect diseases such as heartworm disease, feline leukaemia virus infection, Lyme disease, equine infectious anaemia, and many others.
Toxicology is the branch of science that studies poisons and how they affect animals. If your vet suspects that your pet has been poisoned, samples will be collected for toxicological testing to identify the venom and the amount of damage it may have caused. Some common poisons can be quickly identified. Quick identification of poison can be critical to your pet’s survival. In other cases, samples can be sent to an outside laboratory that can accurately analyze a much wider range of poisons. If your pet has eaten something toxic, your vet may ask you to bring a sample for testing.