Erosive Enteritis and Intestinal Obstructions Caused by Decomposed Granite in a Flock of Lesser Flamingos ().

Decomposed granite is a material commonly used in zoos as a base for flamingo exhibits. In 2012, the artificial turf over the decomposed granite in the Fort Worth Zoo flamingo exhibit was removed and pressure washed, the granite was replaced, and the turf was then restretched in place. Approximately 8 months later, 3 lesser flamingos () showed signs of lethargy and hematochezia. Results of physical examination revealed poor body condition in all birds, with variable hematologic abnormalities, including anemia, hypoproteinemia, and electrolyte disturbances. Radiographs of birds showed large amounts of radiopaque material in the ventriculus and dilated intestinal loops. Two birds died either during treatment or surgery, and 1 bird was euthanatized. Postmortem examination of all 3 birds revealed large amounts of fine, granite-like material in the ventriculus and intestines, severe congestion of intestinal mucosa, and obstruction of intestinal lumen by caseous plugs surrounded by fecal material. Microscopic evaluation of the material removed from the ventriculus showed birefringent crystals that corresponded to microscopic silica grains, consistent with the decomposed granite from the exhibit. Histologic examination of tissues showed marked chronic erosive colitis, mild erosive proventriculitis, and lesions in the muscular layer of the ventriculus. Subsequently, 82 remaining flamingos in the flock were radiographed. Results showed the same material in the ventriculus of most birds, but no intestinal obstructions were identified. Different treatment techniques were attempted unsuccessfully to remove the material from the flamingos that had the largest amount of decomposed granite in their gastrointestinal tracts. Ultimately, all birds were treated with oral gastrointestinal protectants, adsorbents, laxatives, and lubricants, along with antibiotics administered in drinking water. No further mortalities occurred once medical treatments were implemented.