Granulomatous enteritis in a Parrot- Mycobacterium genavense
History: An 11 year old intact male Scaly-headed parrot (Pionus maximiliani) had diarrhea off and on for a few weeks, then died.
The bird was slightly thin with a prominent keel.
Small intestine: There are large numbers of foamy macrophages in the
submucosa and mucosa which cause thickening, blunting, and fusion of
the villi. There are moderate numbers of lymphocytes and plasma cells in
the lamina propria surrounding the granulomas. The cytoplasm of the
macrophages contains numerous acid fast bacilli. There is diffuse
involvement of the small intestine.
Kidney: Diffusely the basement membranes of the glomerular capillaries
in the glomerular tufts are segmentally thickened with a PAS positive
proteinaceous material. Renal tubules contain moderate amounts of PAS
positive proteinaceous material. There is a focal granuloma in the extra-
renal mesentery adjacent to the testis with small numbers of heterophilis,
macrophages and a central zone of necrotic eosinophilic material with
numerous cholesterol clefts.
Small intestine: Granulomatous enteritis, diffuse, severe, with intracytoplasmic acid fast bacilli consistent with Mycobacterium spp.
Kidney: Membranous glomerulonephritis, diffuse, global, with tubular proteinosis.
A PCR test identified Mycobacterium genavense in the small intestine. The changes in the kidneys were presumed to be secondary to chronic antigenic stimulation leading to immune complex deposition in the glomerular capillary basement membranes.
Weight loss is common in birds with any chronic disease, and often manifests as pectoral muscle atrophy which produces a concave contour to the breast and a prominent keel bone.