Comparison of Two Diagnostic Methods to Detect Insulin Dysregulation in Horses Under Field Conditions

Characterisation of the oral glucose and sugar tolerance tests and the enteroinsular axis response in healthy adult donkeys

“…The OSTT was performed using the high dose described for ponies and horses (0.45 mL/kg), 20,24 however, the response in the donkeys of this study was lower for glucose (100‐120 mg/dL vs 130‐190 mg/dL) and insulin (6‐8 µIU/mL vs 135 µIU/mL, using both radioimmunoassay technique), but similar to values reported with the low‐dose protocol in ponies (0.15 mL/kg). Glucose and insulin curve peaks (120‐300 minutes and 120‐150 minutes, respectively) were right‐shifted in our donkeys compared with values reported for healthy horses and ponies using radioimmunoassay (glucose peak at 60 and 55 minutes and insulin peak at 60 and 75 minutes, horses and ponies, respectively) 24,36,37 .…”

“…Donkeys had a baseline plasma glucose concentration <110 mg/dL and plasma insulin concentration <20 µIU/mL. These values were used according to studies previously published by our research group in donkeys, although a lower insulin cut‐off value has also been proposed by other authors in horses and ponies in order to increase the sensitivity of baseline insulin for ID diagnosis 19,20 …”

“…These values were used according to studies previously published by our research group in donkeys, although a lower insulin cut-off value has also been proposed by other authors in horses and ponies in order to increase the sensitivity of baseline insulin for ID diagnosis. 19,20 The following morphometric variables were measured: body mass index (BMI), body condition score (BCS), neck score (NS), neck circumference (NC) and neck circumference to height ratio using formulas described for donkeys and horses. 21,22 Three independent evaluators graded BCS and NS using previous scales: BCS from 1 (very thin) to 9 (obese) and the NS from 0 to 4.…”

“…Differences between species could be attributable to inter-species effect, idiosyncrasies in gastric emptying, intestinal glucose sensing, intestinal glucose absorption or incretins release; since repeatability for these challenges have not been evaluated in donkeys, it has been reported to be good in other equids. 35 The OSTT was performed using the high dose described for ponies and horses (0.45 mL/kg), 20,24 however, the response in the donkeys of this study was lower for glucose (100-120 mg/dL vs 130-190 mg/dL) and insulin (6-8 µIU/mL vs 135 µIU/mL, using both radioimmunoassay technique), but similar to values reported with the low-dose protocol in ponies (0.15 mL/kg). Glucose and insulin curve peaks (120-300 minutes and 120-150 minutes, respectively) were right-shifted in our donkeys compared with values reported for healthy horses and ponies using radioimmunoassay (glucose peak at 60 and 55 minutes and insulin peak at 60 and 75 minutes, horses and ponies, respectively).…”

Pituitary Pars Intermedia Dysfunction and Metabolic Syndrome in Donkeys

“…In horses, baseline insulin and glucose concentrations are recommended as a screening test for metabolic syndrome (high specificity), but the sensitivity is not adequate for ruling out EMS [39]. Newer research suggests that the cut-off values for suspected insulin dysregulation/resistance in horses might be lower than initially anticipated [40,41]. Furthermore, glucose and insulin concentrations in donkeys may be altered by previous transportation [42].…”