Diabetes mellitus in a domesticated Spanish mustang.
An 18-year-old Spanish Mustang mare was referred for evaluation of progressive weight loss and persistent hyperglycemia. Clinicopathologic abnormalities included marked hyperglycemia and glycosuria. Serum cortisol concentration was appropriately decreased following administration of dexamethasone, indicating that the horse did not have pituitary pars intermedia dysfunction. Serum insulin and plasma C-peptide concentrations were low, suggesting that hyperglycemia was a result of decreased secretion of insulin by pancreatic beta cells. In addition, glucose concentration did not return to the baseline concentration until 5 hours after i.v. administration of a glucose bolus, suggesting that insulin secretion, insulin effect, or both were reduced. However, i.v. administration of insulin caused only a slight decrease in the plasma glucose concentration, giving the impression that the action of insulin was impaired. Within 5 hours after administration of a combination of glyburide and metformin, which is used to treat diabetes mellitus in humans, the glucose concentration was within reference limits. The horse was euthanized, and a postmortem examination was done. Immunohistochemical staining of sections of the pancreas revealed attenuation of the pancreatic islet beta-cell population, with beta cells that remained generally limited to the periphery of the islets. These findings indicate that, albeit rare, pancreatic beta-cell failure may contribute to the development of diabetes mellitus in horses.
Johnson
Philip J
PJ
Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA.
Scotty
Nicole C
NC
Wiedmeyer
Charles
C
Messer
Nat T
NT
Kreeger
John M
JM
D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy / Q000662:veterinary*; D005260:Female; D005905:Glyburide / Q000627:therapeutic use*; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D006736:Horses; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007515:Islets of Langerhans / Q000503:physiopathology*; D008687:Metformin / Q000627:therapeutic use*; D016896:Treatment Outcome
D001786:Blood Glucose; C417231:Glucovance; D007004:Hypoglycemic Agents; D008687:Metformin; D005905:Glyburide