Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance.
OBJECTIVE
To compare obese horses with insulin resistance (IR) with nonobese horses and determine whether blood resting glucose, insulin, leptin, and lipid concentrations differed between groups and were correlated with combined glucose-insulin test (CGIT) results.


METHODS
7 obese adult horses with IR (OB-IR group) and 5 nonobese mares.


METHODS
Physical measurements were taken, and blood samples were collected after horses had acclimated to the hospital for 3 days. Response to insulin was assessed by use of the CGIT, and maintenance of plasma glucose concentrations greater than the preinjection value for > or = 45 minutes was used to define IR. Area under the curve values for glucose (AUC(g)) and insulin (AUC(i)) concentrations were calculated.


RESULTS
Morgan, Paso Fino, Quarter Horse, and Tennessee Walking Horse breeds were represented in the OB-IR group. Mean neck circumference and BCS differed significantly between groups and were positively correlated with AUC values. Resting insulin and leptin concentrations were 6 and 14 times as high, respectively, in the OB-IR group, compared with the nonobese group, and were significantly correlated with AUC(g) and AUC(i). Plasma nonesterified fatty acid, very low-density lipoprotein, and high-density lipoprotein-cholesterol (HDL-C) concentrations were significantly higher (86%, 104%, and 29%, respectively) in OB-IR horses, and HDL-C concentrations were positively correlated with AUC values.


CONCLUSIONS
Measurements of neck circumference and resting insulin and leptin concentrations can be used to screen obese horses for IR. Dyslipidemia is associated with IR in obese horses.
Frank
Nicholas
N
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA.
Elliott
Sarah B
SB
Brandt
Laura E
LE
Keisler
Duane H
DH
D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D006728:Hormones / Q000097:blood*; D006734:Horse Diseases / Q000097:blood* / Q000473:pathology; D006736:Horses; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood* / Q000627:therapeutic use; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood*; D008297:Male; D009765:Obesity / Q000097:blood / Q000150:complications / Q000473:pathology / Q000662:veterinary*
D001786:Blood Glucose; D006728:Hormones; D007004:Hypoglycemic Agents; D007328:Insulin; D020738:Leptin; D008055:Lipids