SYSTEMIC AMYLOIDOSIS IN A POPULATION OF PRONGHORN ANTELOPE (ANTILOCAPRA AMERICANA).

ABSTRACT

Thirteen pronghorn antelope (Antilocapra americana) from a single captive herd at the Columbus Zoo and Aquarium underwent complete or partial necropsies between 1997 and 2016. Ten of the 13 animals had histologic evidence of amyloidosis resulting in a 77% prevalence. Histologic and ultrastructural changes were characterized in an attempt to determine the underlying cause of the amyloid. Amyloid detection was performed through histologic examination of hemotoxylin and eosin and Congo red-stained microscopic slides for all 13 animals. Transmission electron microscopy and mass spectrometry was performed on renal tissue from two animals. Pedigree analysis and retrospective investigation into the clinical histories was performed. Histologically, 9/10 animals had amyloid present in the kidneys, 8/10 in the liver, 9/10 in the spleen, 4/10 in the gastrointestinal tract, 3/10 in the adrenal glands, and 2/10 in the thyroid glands. Transmission electron microscopy demonstrated glomerular deposits consistent with amyloid. Mass spectrometry performed on renal specimens from two animals revealed the presence of serum amyloid A. Eight of the 10 animals diagnosed with systemic amyloidosis had a clinical history of haemonchosis (elevated fecal strongyle count), 5/10 were diagnosed with pneumonia postmortem, and 7/10 had postmortem findings consistent with negative energy balance. Serum amyloid A, and ß and γ globulin levels were evaluated in four cases of amyloidosis, and all were within normal ranges for healthy domestic cattle. It was possible that the herd's amyloidosis was associated with a hereditary defect that could be exacerbated by chronic inflammation. However, there was no significant association between the mean degree of relatedness and presence of amyloidosis. In conclusion, systemic amyloidosis in this captive population of pronghorn is common. It is likely reactive and secondary to underlying chronic inflammation caused by haemonchosis and/or pneumonia.