Point-of-Care Diagnostics in Equine Practice

ADAPTATION OF A POINT-OF-CARE CANINE PROGESTERONE TEST FOR USE OF PARTURITION PREDICTION IN CAPTIVE ASIAN ELEPHANTS (ELEPHAS MAXIMUS): PROOF OF CONCEPT

In the Asian elephant (Elephas maximus), the levels of progesterone products 5α-pregnane, 3α-hydroxypregnane, and 17α-progesterone are elevated during pregnancy. Detection of a sudden decrease in blood progesterone product levels in the final days of pregnancy is considered an objective way of predicting impending parturition. Point-of-care (POC) tests eliminate the cost involved in transporting samples to an external laboratory and provide an almost instant result, facilitating decision-making for animal monitoring and management. This proof-of-concept study aims to investigate the ability of the AgPlus POC immunoassay system to measure 4-pregnen-3,20-dione in pregnant elephant serum samples and adapt the method for detection of the preparturient progesterone decrease. Frozen serum samples of two pregnant elephants (N = 82) and fresh serum samples of one pregnant elephant (N = 10) were analyzed using both the POC method and a radioimmunoassay in a reference laboratory. Statistical analysis of the data showed that there was no significant difference between the two methods for detection of the progesterone drop, indicating that the POC method can be considered appropriate for use in elephant parturition prediction. Refinement of the methodology, an increase of sample size, and temporal tandem radioimmunoassay would be required to further validate this method for use in elephant reproductive management.

Point-of-care testing in companion and food animal disease diagnostics

Laboratory diagnoses of animal diseases has advanced tremendously in recent decades with the advent of cutting-edge technologies such as real-time polymerase chain reaction, next generation sequencing (NGS), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and others However, most of these technologies need sophisticated equipment, laboratory space and highly skilled workforce. Therefore, there is an increasing market demand for point-of-care testing (POCT) in animal health and disease diagnostics. A wide variety of assays based on antibodies, antigens, nucleic acid, and nanopore sequencing are currently available. Each one of these tests have their own advantages and disadvantages. However, a number of research and developmental activities are underway in both academia and industry to improve the existing tests and develop newer and better tests in terms of sensitivity, specificity, turnaround time and affordability. In both companion and food animal disease diagnostics, POCT has an increasing role to play, especially in resource-limited settings. It plays a critical role in improving animal health and wellbeing in rural communities in low- and middle-income countries. At the same time, ensuring high standard of quality through proper validation, quality assurance and regulation of these assays are very important for accurate diagnosis, surveillance, control and management of animal diseases. This review addresses the different types of POCTs currently available for companion and food animal disease diagnostics, tests in the pipeline and their advantages and disadvantages.

Isothermal Nucleic Acid Amplification Technologies for the Detection of Equine Viral Pathogens

Simple Summary

Equine viral diseases remain a prominent concern for human and equine health globally. Many of these viruses are of primary biosecurity concern to countries that import equines where these viruses are not present. In addition, several equine viruses are zoonotic, which can have a significant impact on human health. Current diagnostic techniques are both time consuming and laboratory-based. The ability to accurately detect diseases will lead to better management, treatment strategies, and health outcomes. This review outlines the current modern isothermal techniques for diagnostics, such as loop-mediated isothermal amplification and insulated isothermal polymerase chain reaction, and their application as point-of-care diagnostics for the equine industry.

Abstract

The global equine industry provides significant economic contributions worldwide, producing approximately USD $300 billion annually. However, with the continuous national and international movement and importation of horses, there is an ongoing threat of a viral outbreak causing large epidemics and subsequent significant economic losses. Additionally, horses serve as a host for several zoonotic diseases that could cause significant human health problems. The ability to rapidly diagnose equine viral diseases early could lead to better management, treatment, and biosecurity strategies. Current serological and molecular methods cannot be field-deployable and are not suitable for resource-poor laboratories due to the requirement of expensive equipment and trained personnel. Recently, isothermal nucleic acid amplification technologies, such as loop-mediated isothermal amplification (LAMP) and insulated isothermal polymerase chain reaction (iiPCR), have been developed to be utilized in-field, and provide rapid results within an hour. We will review current isothermal diagnostic techniques available to diagnose equine viruses of biosecurity and zoonotic concern and provide insight into their potential for in-field deployment.

Detection of Streptococcus equi subsp. equi in guttural pouch lavage samples using a loop-mediated isothermal nucleic acid amplification microfluidic device

Background

Rapid point‐of‐care (POC) detection of Streptococcus equi subsp. equi (S. equi) would theoretically reduce the spread of strangles by identifying index and carrier horses.

Hypothesis

That the eqbE isothermal amplification (LAMP) assay, and the same eqbE LAMP assay tested in a microfluidic device format, are comparable to a triplex real‐time quantitative polymerase chain reaction (qPCR) assay that is commonly used in diagnostic labs.

Samples

Sixty‐eight guttural pouch lavage (GPL) specimens from horses recovering from strangles.

Methods

Guttural pouch lavage specimens were tested for S. equi retrospectively using the benchtop eqbE LAMP, the eqbE LAMP microfluidic device, and compared to the triplex qPCR, that detects 2 S. equi‐specific genes, eqbE and SEQ2190, as the reference standard using the receiver operating characteristic area under the curve (ROC).

Results

The 27/68 specimens were positive by benchtop eqbE LAMP, 31/64 by eqbE LAMP microfluidic device, and 12/67 by triplex qPCR. Using the triplex PCR as the reference, the benchtop eqbE LAMP showed excellent discrimination (ROC Area = 0.813, 95% confidence interval [CI] = 0.711‐0.915) as did the LAMP microfluidic device (ROC Area = 0.811, 95% CI = 0.529‐0.782). There was no significant difference between the benchtop LAMP and LAMP microfluidic device (ROC Area 0.813 ± 0.055 vs 0.811 ± 0.034, P = .97).

Conclusions

The eqbE LAMP microfluidic device detected S. equi in GPL specimens from convalescent horses. This assay shows potential for development as a POC device for rapid, sensitive, accurate, and cost‐efficient detection of S. equi.