Objectives—To determine whether increased glucose
metabolism is the potential cause of the
decreased plasma glucose curve determined after
oral glucose tolerance testing in horses with lower
motor neuron degeneration.
Animals—3 horses with signs suggestive of lower
motor neuron degeneration, 1 horse with malignant
melanoma with multiple metastases, and an obese
but otherwise healthy horse.
Procedures—Glucose metabolism was assessed by
use of the hyperglycemic clamp and euglycemic
hyperinsulinemic clamp techniques.
Results—Mean rate of glucose metabolism of
horses with lower motor neuron degeneration was
significantly greater (mean, 3.7 times greater than
control horses; range, 2.1 to 4.8 times greater)
than that reported in 5 healthy control horses
(41 ± 13 µmol/kg/min vs 11 ± 4.5 µmol/kg/min,
respectively). In addition, one of the affected horses,
an 8-year-old warmblood gelding, had a 5.6-
times increased sensitivity to exogenously administered
insulin, compared with that reported in 5
healthy control horses. Pancreatic insulin secretion
was not insufficient in horses with lower motor
neuron degeneration. Findings in the 2 diseased
control horses were unremarkable.
Conclusions and Clinical Relevance—Increased
glucose metabolism in horses with lower motor neuron
degeneration may be the cause of the decreased
plasma glucose curve detected after oral glucose tolerance
testing. This finding could aid in developing
supportive treatments with respect to adequate glucose
and vitamin E supplementation. (Am J Vet Res 2005;66:271–276)