Application of Veterinary Diagnostic Kits and the Use of Rapid Test Kits in Diseases Diagnosis in India: An Overview
Disease diagnosis of animals enables veterinarians to detect the root causes of infections and provide an early prognosis to prevent the degradation of animal health. Farmers must check the health of their farm animals periodically, as most of them are food-producing animals. The foods derived from animals should be disease-free as there is always a chance of humans getting infected after consuming infected animal-derived foods. In addition, if the disease or infection is not detected early, it can lead to the death of the infected animals, leading to economic losses for farmers. Rapid test kits help in early diagnosis as the results are generated in a few minutes. Moreover, in centralized animal healthcare settings such as veterinary hospitals, clinics, and reference laboratories, either the animals must be brought in for testing, or the samples must be sent for testing. This may cause inconvenience to farmers as transporting large animals is difficult, and there is also the risk of the samples getting damaged during transport, which may lead to the generation of false results. Moreover, the time taken to generate results through conventional testing methods is significantly more compared to rapid tests, which may further delay the treatment of animals. Rapid tests are portable kits or analyzers that can be used by farmers in a setting of their choosing. These tests are simple to use and can be performed without any professional training.
Diagnostic kits are widely used to detect pathogens or their associated immune responses in individual animals or herds. Potential applications include the confirmation of infection in clinically diseased animals, surveillance of infectious animal diseases to support control and eradication programmes, and certification of health status for international trade. Since the results of these diagnostic tests have important implications for the management of diseases, it is important that their fitness for use be appropriately validated for the species, specimens and systems in which they will be used.
Companion animals or pets are considered a part of the family and treated as family members. There has been an increase in awareness regarding the importance of regular checkups of pets. Heartworm, parvovirus, and ringworm are diseases commonly found in dogs. Rapid test kits for diseases such as heartworm and feline leukemia are cheaper and more affordable than other testing methods. Frequent testing for these diseases with other methods such as PCR is expensive. Hence, simplicity, portability, and lower costs are factors boosting the adoption of rapid tests.
Animal disease diagnostics forms a connecting link between the cause and cure of any disease, and thereby, plays a fundamental role in disease management and prevention. A small outbreak of disease can pose a threat to the entire animal community. Thus, to ensure the overall wellbeing of animals, the practice of veterinary diagnostics becomes essential. This field is growing exponentially, driven by the need to control and prevent diseases in animals. Data collected from millions of animal tissues and fluid samples help create drugs and vaccines. A major push in the development of animal disease diagnostics has been towards innovative methods that can provide complete and robust results in less than 24 hours or even during the course of the initial examination of the animal.
Key Components of Veterinary Diagnostic System
Vet Laboratory
The vet laboratory provides a facility for medical testing of infectious toxins or agents in animal diagnostic samples. Veterinary professionals such as public officials related to wildlife management or public health, animal owners, and scientists submit these samples for analysis. Special testing laboratories include molecular, pathology, bacteriology, Health Assurance Testing Services (HATS), toxicology, nutrition, and virology testing centers.
Vet Devices
The FDA defines veterinary (vet) devices as instruments, apparatuses, or accessories used for diagnosis of diseases, wherein vet devices include diagnostic test kits, syringes, needles, surgical instruments, X-ray equipment, prosthetic devices, and dental appliances.
Veterinary Diagnostic Test Kits
Various test kits used to control animal movement include kits for activated clotting time in dogs and cats, refrigerated veterinary diagnostic test kits with a shelf life of up to two years, and non-refrigerated test kits with a shelf life of up to 18 months, urine testing, and parasite detection systems.
Veterinary Diagnostic Techniques
Quality assured diagnostics are important for providing appropriate treatment. Hence, the diagnostic technique should be rapid, sensitive, specific, and cost-effective. The classical diagnostic approach includes microscopic technique, cell culture, and serologic assays. With advancements in healthcare, a large array of diagnostic tests have become available, and various modern diagnostic modalities are often routinely used.
Early diagnosis plays a vital role in making critical clinical decisions in veterinary medicine. In traditional diagnostic systems, samples are collected from clinics and sent to central laboratories for evaluation. The test results are then communicated to the veterinarian after a delay of an average of 24-72 hours, depending on the test and the laboratory load. This process delays treatment from the time of identification of signs by the veterinarian to the provision of appropriate therapy.
What are Point-of-Care Diagnostics?
Point-of-care diagnostics consist of analytical systems which provide clinically relevant information without the need for a core diagnostic laboratory. These tests are simplified versions of traditional laboratory assays and are designed to provide information at the point-of-use, while giving the individual practitioner a significant amount of autonomy. There are numerous reasons why POCT should be incorporated into veterinary clinics for differential diagnosis;
-The tests can be performed with minimal scientific and technical background.
-They do not require complex training.
-The reagents are stable, have a long shelf life and do not require special storage.
-POC kits usually contain all the materials and disposables necessary for the test.
-POCT allows for massive timesavings and easy access to complex technologies.
There are two major types of test categories:
- Screening Tests:Tests used for clinically healthy animals to detect the possibility of a disease
- Confirmatory/Diagnostic Tests:Tests used for clinically diseased animal to confirm the diagnosis or classify disease status
Advances in Diagnostic Technology by Integrating the Use of New Tools
Traditionally, laboratory diagnostics for veterinary pathogens have relied on methods of detecting the pathogen by culture or antibodies, using varied techniques, such as neutralization, Enzyme-linked Immunosorbent Assay (ELISA), agar gel immunodiffusion, and complement fixation. Over the years, veterinarians have incorporated new molecular diagnostic techniques, such as Polymerase Chain Reaction (PCR) and Western blot, as well as improved older techniques by using recombinant antigens, monoclonal antibodies, and synthetic peptides. Despite the routine use of conventional diagnostic assays, new molecular techniques have enabled veterinarians to use new tools for rapid and specific diagnosis of animal disease in real-time.
Improved immunoassays
The production of specific proteins or peptides that serve as target antigens or positive control reagents is possible with new biotechnological methods, such as the cloning of genes, overexpression of immunogens, and use of expression vectors and peptide synthesis in existing and newly-developed immunoassays. The use of these improved antigens can increase the specificity or sensitivity of immunoassays by providing a more defined target for binding antibody, which, in turn, can reduce serial-to-serial (lot-to-lot) variation of test kit performance.
Biosensors
Through the development of biosensors, the detection of either the agent or antibodies has been possible. Biosensors use a receptor (usually an antibody) to identify the target pathogen or a disease-specific antibody and a transducer that converts a biological interaction into a measurable signal. Some of the transducer technologies under-development include electrochemistry, interferometry, reflectometry, resonance, and fluorimetry. Biosensors, coupled with sophisticated instrumentation, are used to produce highly-specific analytical tools, most of which are mainly used for research and development due to their high cost.
Nucleic acid diagnostics
The inclusion of nucleic acid-based diagnostics in veterinary medicines has redefined the level of information for animal disease control programs. Nucleic acid detection techniques such as PCR and real-time PCR have led to the development of rapid, specific assays. The use of such single-tube, closed assay detection techniques decrease the problem associated with cross-contamination among samples and facilitate easy detection of positive samples effectively based on the amount of fluorescence released during amplification.
Non-polymerase chain reaction techniques for nucleic acid detection
With the advent of promising and sensitive gene amplification techniques such as Nucleic Acid Sequence-based Amplification (NASBA), the need for thermocycler is eliminated. The NASBA is an isothermal system, operated at a single temperature. It is a two-step process that involves an initial enzymatic amplification of the nucleic acid targets, followed by the detection of generated amplicons.
Proteomics
Proteomic technologies have immense potential in veterinary diagnostic applications as they target the patterns of protein expression of the target analyte, such as virus, bacteria, parasite, etc. Various proteomic techniques that are currently applied to veterinary science, include proteomic approaches to animal disease pathogenesis, recent achievements in immunoproteomics (i.e. identification of antigens involved in immune response through proteomic techniques), histoproteomics (i.e. the application of proteomics in tissue processed for immunohistochemistry), and clinical proteomics (i.e. the identification of new biomarkers of animal diseases through proteomics).
Nanotechnology
Nanotechnology test platforms such as nanoarrays and nanochips have the potential to analyze a sample to determine an array of infectious agents on a single chip. This involves identification of specific strains or serotypes of disease agents (including identification of specific influenza strains) or the differentiation of diseases caused by different viruses but with similar clinical signs, such as vesicular viral diseases.
Techniques & diagnostics tools
Accurate, quality-tested diagnostic techniques are vital to diagnosing illness and prescribing the correct treatment method. As such, diagnostic techniques must provide a rapid response, high sensitivity and specificity, cost-effectiveness, and they must be accurately identified with veterinary labels. As healthcare treatments have advanced, so have diagnostic test kits, with an extensive array of tests now available. There are two main types of tests available: screening tests, used to detect disease in otherwise clinically healthy animals, and confirmatory tests, used to confirm a diagnosis in clinically diseased animals. These diagnostic tests can be further broadly segmented into the following categories:
Blood tests: Blood work includes the complete blood count measures, representing the number of cells of different types circulating in the bloodstream. One of the most common tests is a complete blood count (CBC) that analyzes the numbers and appearance of blood cells. The CBC is important in the diagnosis and monitoring of disease and infection. Specialized tests can also be done when trying to confirm a specific diagnosis.
Urinalysis: This evaluates the physical and chemical composition of urine. Urinalysis provides essential diagnostic information about the condition of urinary and genital tracts and can help identify a number of systemic diseases, such as diabetes, liver disease, and Cushing’s disease.
Fecal exam: These diagnostic tests are used to detect various types of intestinal parasites, such as worms. Intestinal parasites are known to infect animals often without causing outwardly noticeable symptoms and can go undetected as a result. As parasites can be transferred to other pets or even humans, routine fecal analysis is often recommended to ensure animals stay healthy.
Radiography: X-Ray radiography is a commonly used veterinary diagnostic tool. By exposing the animal to a beam of x-rays, vet technicians can produce a high-quality image of the animal’s internal organs and bones. This can be used to diagnose various conditions and injuries, including fractures, arthritis, and pneumonia.
Ultrasound: A non-invasive diagnostic tool that allows for real-time imaging of an animal’s abdomen, chest, or heart. Typically performed without the need for sedation or anesthesia, it is a more comprehensive imaging technique than x-rays. As such, ultrasound is a quick and efficient way to diagnose disease and various health problems, particularly for recognizing cysts and tumors.
Electrocardiogram (ECG): ECG is a valuable veterinary science tool that is also easy to perform. It is used in animals that are suspected of having an impaired cardiac function, particularly arrhythmia. ECG may also yield useful information regarding chamber dilation and hypertrophy.
Microscopy: A laboratory microscope can be used to analyze samples obtain from the animal quickly. This can include skin scrapings, ear swabs, and skin mass aspirates.
Future trends & potential impact
Veterinary diagnostics can be further developed to provide a more significant analysis of samples and tissues. New biotechnological techniques, like gene cloning, immunogen overexpression assays, or the latest immunohistochemistry procedures, have made it possible to produce specific proteins and peptides that can serve as target antigens in a new generation of immunoassays. These techniques can improve the specificity and sensitivity of assays by providing a better-defined antibody binding target, and therefore reduce intra-kit variability. Advanced proteomic techniques can target the protein expression profiles of viruses, bacteria, and parasites, providing a useful diagnostic tool for detecting disease. These includes immunoproteomic methods, which study proteins involved in the immune response, histoproteomic approaches applied to tissues processed for immunohistochemistry, and clinical proteomics, which identifies biomarkers of animal disease.
Blood analysis can also be used to detect the presence of specific biosensors, which commonly use an antibody as a receptor to identify target pathogens, or disease-specific antibodies. The antibody is then converted into a measurable signal, which can be achieved in various ways, such as electrochemistry, interferometry, reflectometry, resonance, and fluorimetry. Moreover, nucleic acid detection techniques such as polymerase chain reaction (PCR) and real-time PCR (RT-PCR) have led to the development of rapid, specific diagnostic assays. This has been further improved upon with gene sequencing techniques that can screen the entire genome of an animal for markers of disease. Another benefit of these assays is the ability to use single-tube, closed assay detection techniques, which decreases the possibility of cross-contamination among samples.
Animal Diagnostic Market: An Overview
The globalization of trade in animals and animal products is a major driver for the improvement of the analytical and diagnostic quality of tests. The global companion veterinary diagnostics market is expected to reach USD 6.51 billion by 2022, at a CAGR of 20.1% from 2017 to 2022.
On the basis of technology, the companion veterinary diagnostics market is broadly segmented into:
- Polymerase Chain Reaction (PCR)
- Real-time Polymerase Chain Reaction (RT-PCR)
- In situ Hybridization (ISH)
- Immunohistochemistry (IHC)
- Gene Sequencing
- Other Technologies
Global Veterinary Diagnostic Market Players
The global veterinary diagnostics market is dominated by IDEXX Laboratories (U.S.) and VCA Antech (U.S.). A large share of IDEXX and Antech is attributed to their revenue from the reference laboratories business, where they have a competitive edge over other leading players in the market.
Other major players are:
- Abaxis Corporation (U.S.)
- Heska Corporation (U.S.)
- Mindray Medical (China)
- Neogen Corporation (U.S.)
- Thermo Fisher Scientific Inc. (U.S.)
The global veterinary rapid tests market is projected to reach USD 854 million by 2024 from USD 573 million in 2019, at a CAGR of 8.3% during the forecast period. Growth in this market is driven by the increasing prevalence of zoonotic diseases among companion and livestock animals and the growing need for the rapid detection of these diseases.
By application, the viral diseases segment accounted for the largest market share of the market.
On the basis application, the veterinary rapid tests market has been segmented into viral diseases, bacterial diseases, parasitic diseases, allergies, and other applications. The viral diseases segment is excepted to account for the largest share of the veterinary rapid tests market in 2019. The large share of this segment can be attributed to the rising incidence of zoonotic diseases, growing prevalence of infectious diseases in farm animals, and growing pet health awareness among owners.
The companion animals segment is expected to grow at the highest CAGR during the forecast period.
On the basis of animal type, the veterinary rapid tests market is segmented into companion and livestock animals. The companion animals segment is expected to witness the highest CAGR, owing to the increasing companion animal ownership, growing awareness about animal health among pet owners, and rising pet healthcare expenditure. The companion animals segment is further segmented into dogs, cats, horses, and other companion animals, such as rabbits, birds, and reptiles. In 2019, the market for dogs accounted for the largest share of the veterinary rapid tests market for companion animals.
UPENDRAKUMAR K. PHARMA MARKET ANALYST. MUMBAI
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