April 03, 2017

Blood Sucrose as a Diagnostic Tool for Equine Gastric Ulcer Syndrome

Researchers determined whether blood sucrose was a diagnostically accurate screening test for equine gastric ulcer syndrome in adult horses.
By JoAnna Pendergrass, DVM
Researchers at the University of Pretoria in South Africa determined that blood sucrose was not a diagnostically accurate screening test for equine gastric ulcer syndrome (EGUS) in adult horses. Results of the study were recently published in Acta Veterinaria Scandinavica.
 
EGUS, a common equine disease that primarily affects performance horses, is characterized by erosive and ulcerative stomach lesions. It is further subclassified into equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD). The clinical significance of EGUS remains unknown, in part because many horses with the disease do not show clinical signs.
 
Gastroscopy is the current gold standard for diagnosing EGUS. However, its expense and lack of ready availability make it an unsuitable diagnostic tool for many veterinarians. Sucrose permeability testing is a potential diagnostic alternative to gastroscopy. Because of its large molecular size, sucrose cannot permeate gastrointestinal mucosa unless the mucosa is diseased. Therefore, increased blood sucrose levels after oral sucrose administration can predict gastric disease.
 
The authors tested 101 adult horses with and without naturally occurring gastric disease; 53 horses showed clinical signs of EGUS. The horses, which were used for a variety of purposes, had not received nonsteroidal anti-inflammatory drugs or omeprazole in the previous 7 days. Horses were held off feed and water prior to testing.
 
For gastroscopy, the authors video recorded and took pictures of multiple stomach regions and the proximal duodenum. Immediately following gastroscopy, horses underwent blood sucrose testing. The authors administered sucrose via a nasogastric tube and collected blood samples 45 and 90 minutes after administration.
 
Three raters, blinded to blood sucrose test results, reviewed the recordings and images. Lesions were classified as “gastric” (synonymous with EGUS), “squamous” (synonymous with EGSD), “glandular” (synonymous with EGGD), and “clinically significant” (severe enough to warrant treatment).
 
Results
Gastroscopy
Gastric lesions were identified in 84 of 101 horses; these lesions were clinically significant in 58 of 84 horses.
 
Glandular mucosal lesions were identified in 71 of 101 horses and were primarily fibrinous or focally hemorrhagic. Squamous mucosal lesions were identified in 54 of 101 horses and were primarily small single ulcers.
 
Inter-rater Agreement
Inter-rater agreement was 100% for most lesion observations.
 
Blood Sucrose Concentrations
Blood sucrose concentrations peaked 90 minutes after administration. At the 45- and 90-minute time points, blood sucrose concentrations were lowest in the horses without gastric disease.
 
Diagnostic Accuracy of Blood Sucrose
The authors constructed receiver operator characteristic (ROC) curves for both time points. They then calculated the area under the curve (AUC) for each lesion classification. AUC values ranged from 0.51 to 0.68, falling within the “less accurate” category of overall diagnostic accuracy.
 
Using predetermined blood sucrose concentration cutoff values for EGUS screening, the authors calculated the specificities, sensitivities, and negative and positive predictive values. Specificities and sensitivities were generally low across lesion classifications, confirming that blood sucrose is not diagnostically accurate.
 
Study Limitations and Conclusions
The predominance of small single lesions and lack of extensive, deep ulcerations was a study limitation, the authors noted; the small surface area of the lesions may not have not allowed for sucrose permeation, potentially skewing results.
 
The authors believed that, although blood sucrose testing was not diagnostically accurate in this study, it may still accurately represent true gastric mucosal integrity. Given that lesion assessment using gastroscopy can be highly subjective, the authors proposed comparing blood sucrose test results against histopathology results in future studies. In addition, the authors recommended further evaluation of blood sucrose testing in a population of horses with clinical signs of EGUS, rather than healthy horses.
 
 
Dr. JoAnna Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.

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