The enteroinsular axis during hospitalization in newborn foals.

The enteroinsular axis (EIA) is an energy regulatory system that modulates insulin secretion through the release of enteroendocrine factors (incretins). Despite the importance of energy homeostasis in the equine neonate, information on the EIA in hospitalized foals is lacking. The goals of this study were to measure serum insulin and plasma incretin (glucose-dependent insulinotropic polypeptide [GIP], glucagon-like peptide-1 [GLP-1] and glucagon-like peptide-2 [GLP-2]) concentrations, to determine the insulin and incretin association, as well as their link to disease severity and outcome in hospitalized foals. A total of 102 newborn foals ≤72 h old were classified into hospitalized (n = 88) and healthy groups (n = 14). Hospitalized foals included septic (n = 55) and sick non-septic (SNS; n = 33) foals based on sepsis scores. Blood samples were collected over 72 h to measure serum insulin and plasma GIP, GLP-1 and GLP-2 concentrations using immunoassays. Data were analyzed by nonparametric methods and univariate logistic regression. At admission, serum glucose and insulin and plasma GIP were significantly lower in hospitalized and septic compared to healthy foals (P < 0.01), while plasma GLP-1 and GLP-2 concentrations were higher in hospitalized and septic foals than healthy and SNS foals, and decreased over time in septic foals (P < 0.05). As a percent of admission values, GLP-1 and GLP-2 concentrations dropped faster in healthy compared to hospitalized foals. Serum insulin concentrations were lower in hospitalized and septic non-survivors than survivors at admission (P < 0.01). Hospitalized foals with serum insulin < 5.8 µIU/mL, plasma GLP-1 >68.5 pM, and plasma GLP-2 >9 ng/mL within 24 h of admission were more likely to die (OR = 4.2; 95% CI = 1.1-16.1; OR = 13.5, 95% CI = 1.4-123.7; OR = 12.5, 95% CI = 1.6-97.6, respectively; P < 0.05). Low GIP together with increased GLP-1 and GLP-2 concentrations indicates that different mechanisms may be contributing to reduced insulin secretion in critically ill foals, including impaired intestinal production (GIP, proximal intestine) and pancreatic endocrine resistance to enhanced incretin secretion (GLP-1, GLP-2; distal intestine). These imbalances could contribute to energy dysregulation in the critically ill equine neonate.

Radiographic tracheal lumen to vertebral ratios in the normal American Miniature Horse.

BACKGROUND: Tracheal collapse in horses is reportedly uncommon; however, American Miniature Horses are more commonly affected. There is no description of the tracheal luminal diameter of American Miniature Horses, making early detection of tracheal luminal narrowing difficult. OBJECTIVES: To 1) describe radiographic tracheal luminal diameter in clinically normal American Miniature Horses, 2) report the prevalence of subclinical tracheal collapse in a population of American Miniature Horses, and 3) use tracheal videofluoroscopy to quantify variation in tracheal luminal diameter throughout the respiratory cycle in horses with no clinical respiratory disease. STUDY DESIGN: Descriptive observational reference interval study. METHODS: Thirty-four American Miniature Horses with no reported history of respiratory illness were recruited. Lateral cervical and thoracic radiographs were obtained in unsedated standing horses. Dynamic fluoroscopic images were obtained of the cervical and thoracic trachea throughout the respiratory cycle. Horses were then sedated as needed and tracheoscopy was performed. Twenty-nine horses were categorised as normal, and five horses were categorised as subclinically affected based on 25% or greater tracheal narrowing using tracheoscopy for visual assessment. Radiographic tracheal lumen to vertebral body measurements were obtained throughout the cervical and thoracic trachea. Maximum and minimum fluoroscopic tracheal diameter at each site throughout the respiratory cycle was recorded. RESULTS: A mean, median, 95% confidence interval and bootstrapped 95% reference interval of radiographic tracheal diameter to vertebral body ratios were generated in normal horses. The prevalence of subclinical tracheal collapse in this population of American Miniature Horses is 14.7%. MAIN LIMITATIONS: Bootstrapped reference range was generated from 29 horses. CONCLUSIONS: Radiographic tracheal measurements and ratios of the tracheal diameter to vertebral body in the normal American Miniature Horse are described herein and can be used as a guideline when screening for tracheal disease in American Miniature Horses. The prevalence of subclinical tracheal collapse in American Miniature Horses may be higher than previously reported.