Nasal Amyloidosis in a Horse

A 16-year-old Quarter Horse was admitted to the Veterin ary Hospital after recurrent epistaxis episodes. Dy spnea and intolerance to exercise were noticed. An irregular mu ltinodular mass was observed in the mucosa of the ro stral nasal cavity, causing partial stenosis of the anterior airways. To improve the respiratory condition of the animal, m ost of the mass was surgically removed. Histologic examination revealed eosinophilic hyaline material in the lamina propria , walls of submucosal lymphatic and blood vessels, and basement membrane of mucosal glands of the nasal cavity. This materia l stained orange-red with Congo-red, with the characteristic green birefri ngence under polarizing light, confirming the amylo id diagnosis. Giant cells and mononuclear cell infiltrate were also observed. One year after the partial removal of the lesion, th e horse had only mild respiratory signs .