Presence of Myeloperoxidase in Lamellar Tissue of Horses Induced by an Euglycemic Hyperinsulinemic Clamp

Laminitis is a pathology of the equine digit leading to a failure of the dermo-epidermal
interface. Neutrophil activation is recognized as a major factor in SIRS-associated
laminitis. Less is known about the role of neutrophil activation in laminitis associated
with metabolic disorders. The aim of this descriptive study was to observe
whether myeloperoxidase is increased in the laminae during early stage laminitis in
three horses subjected to a prolonged euglycemic hyperinsulinemic clamp (pEHC).
After 48 h of pEHC-treatment, horses were subjected to euthanasia. Two healthy
horses are used as control. Histological sections of lamellar tissue from all horses
were immunohistochemically stained for myeloperoxidase and counterstained with
hematoxylin-eosin. Histopathological changes that characterize insulin-induced laminitis
and increased presence of myeloperoxidase, especially in the dermal lamellae, were
increased in histologic sections of pEHC-treated horses. Neutrophil myeloperoxidase
release may contribute to the pathophysiology of endocrinopathic laminitis.