Abstract: Equine metabolic syndrome (EMS), like human metabolic syndrome, comprises a collection of clinical signs related to obesity, insulin dysregulation and susceptibility to secondary inflammatory disease. Although the secondary conditions resulting from EMS can be life-threatening, diagnosis is not straightforward and often complicated by the presence of other concurrent conditions like pituitary pars intermedia dysfunction (PPID). In order to better characterize EMS, we sought to describe the variation within, and correlations between, typical physical and endocrine parameters for EMS. Utilizing an unsupervised statistical approach, we evaluated a population of Arabian horses using a physical examination including body measurements, as well as blood plasma insulin, leptin, ACTH, glucose, and lipid values. We investigated the relationships among these variables using principle component analysis (PCA), hierarchical clustering, and linear regression. Owner-assigned assessments of body condition were one full score (on a nine-point scale) lower than scores assigned by researchers, indicating differing perception of healthy equine body weight. Rotated PCA defined two factor scores explaining a total of 46.3% of variation within the dataset. Hierarchical clustering using these two factors revealed three groups corresponding well to traditional diagnostic categories of "Healthy", "PPID-suspect", and "EMS-suspect" based on the characteristics of each group. Proxies estimating up to 93.4% of the composite "EMS-suspect" and "PPID-suspect" scores were created using a reduced set of commonly used diagnostic variables, to facilitate application of these quantitative scores to horses of the Arabian breed in the field. Use of breed-specific, comprehensive physical and endocrinological variables combined in a single quantitative score may improve detection of horses at-risk for developing EMS, particularly in those lacking severe clinical signs. Quantification of EMS without the use of predetermined reference ranges provides an advantageous approach for future studies utilizing genomic or metabolomics approaches to improve understanding of the etiology behind this troubling condition.
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The research article is about a new approach to diagnosing equine metabolic syndrome (EMS) in Arabian horses using statistical analysis and multiple diagnostic variables rather than relying solely on physical examinations.
Objective of the Study
The study aimed to better characterize and diagnose EMS, a condition in horses that is similar to human metabolic syndrome.
EMS is typically associated with obesity, insulin irregularities and potential for secondary inflammatory diseases, making diagnosis complex due to possible presence of other conditions such as pituitary pars intermedia dysfunction (PPID).
Methodologies and Data Analysis
The research used an unsupervised statistical approach, studying a population of Arabian horses with physical exams and blood tests scoring insulin, leptin, ACTH, glucose, and lipid values.
Using principal component analysis (PCA), the researchers studied the relationships and correlations between these variables, as well as hierarchical clustering and linear regression.
Physical condition assessments provided by horse owners were found to be on average one full point lower than ratings given by researchers, indicating a variance in perceptions of what constitutes a healthy horse weight.
Findings of the Study
Using rotated PCA, two factor scores were identified that accounted for 46.3% of variation within the dataset.
Through hierarchical clustering with these two factors, three groups were defined, correlating well with the traditional diagnostic categories of “Healthy”, “PPID-suspect”, and “EMS-suspect”.
Predictive models were created that could approximate up to 93.4% of the composite “EMS-suspect” and “PPID-suspect” scores using a reduced set of common diagnostic variables. This could make the application of these quantitative scores easier in real-world situations.
Conclusion and Implications for Future Studies
The utilization of breed-specific, comprehensive physical and endocrinological variables in a single quantitative score could potentially enhance the detection of Arabian horses at risk for EMS development, particularly for those not displaying severe clinical symptoms.
Quantifying EMS without predetermined reference ranges could provide a better approach for future genomic or metabolomic studies aiming to understand the underlying causes of EMS.
Cite This Article
APA
Lewis SL, Holl HM, Long MT, Mallicote MF, Brooks SA.
(2018).
Use of principle component analysis to quantitatively score the equine metabolic syndrome phenotype in an Arabian horse population.
PLoS One, 13(7), e0200583.
https://doi.org/10.1371/journal.pone.0200583
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