Point-of-care tests (POCT) provide tools to quickly support the results of veterinary examination. By enabling rapid decisions to be made on site, these technologies have the potential to decrease the costs associated with delayed and incorrect diagnoses.
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.
Lateral Flow POCT
POC devices, which come in the form of dipsticks and lateral flow devices (LFDs), have been designed to determine the infectious disease status in animals. They are widely accepted on account of their simplicity, cost-effectiveness and reproducibility. Both antibody and antigen detection have been incorporated into portable immuno-chromatographic strip tests. When compared with reference laboratory tests, specificity tends to be comparable, while sensitivity can be low. Low sensitivity indicates that a positive result can be trusted, whereas, in the case of negative results, it may be necessary to carry out further confirmatory laboratory testing.
Due to the dilemma of low sensitivity, molecular tests in the form Polymerase Chain Reactions (PCR) are slowly replacing antigen LFD tests. PCR is an established laboratory tool to detect the presence of pathogens in clinical samples, offering superior analytical sensitivity in comparison to antigen detection LFD based assays. Much progress has been made recently in transitioning PCR into POCT platforms, with a number of technologies now commercially available aimed at low resource clinical settings. To perform standard PCRs, expensive sophisticated instrumentation is still necessary. Alternative polymerase chain reaction chemistries have opened the potential for reducing the size, cost and complexity of molecular POCT platforms. Isothermal methodologies have been developed, reducing the requirement for thermal regulation and leading to protocols where reactions are carried out at a single fixed temperature. An example of one type of isothermal POC PCR is Biogal’s molecular DNA and RNA Detection Kits.
Many infectious diseases present with nonspecific and similar signs. Tests that reliably detect and differentiate these infections are needed to adequately diagnose patients and deliver early, appropriate treatment. Serological diagnostic methods are most commonly employed following complete blood counts, blood chemistry and urinalysis. Antibody tests have been shown to have poor sensitivity during the acute phases of infection, when tests are most likely to be performed and high diagnostic efficiency at later stages of the disease. In addition, a single positive titer result is unable to distinguish between current infection and evidence of previous exposure to these pathogens. Both serology and molecular testing are important parts of the final determination of disease statis. Each has its window of opportunity with molecular tests most suitable for early stages of disease and serology for the later stages of disease when an immune response has been established.
One can only conclude that a combination of both POC serology and molecular testing can assist in reaching superior results in diagnosis.
The benefits of transitioning molecular diagnostic technologies into POCT formats are clear in terms of accelerating diagnostic confirmation. However, despite these benefits and numerous technological advances, the uptake of molecular POCT remains relatively low for veterinary diagnostic use due to the increased cost over antigen LTF platforms.
Although the cost of the test is an important consideration, increased accuracy of results, reduced waiting time and the possibility of starting a therapy within the first visit are amongst the main advantages of tests that can be carried out “in-house”.