Hemochromatosis and hemosiderosis in Puerto Rican parrots (Amazona vittata)

The Puerto Rican parrot (Amazona vittata) is endemic to Puerto Rico and is the only native parrot species within the United States. It is one of the most endangered psittacine species globally. Captive breeding programs are... [ view full abstract ]

The Puerto Rican parrot (Amazona vittata) is endemic to Puerto Rico and is the only native parrot species within the United States. It is one of the most endangered psittacine species globally. Captive breeding programs are critical to the Puerto Rican parrot recovery program and reintroduction efforts. Between 1997 and 2016, post mortem evaluations of 264 Puerto Rican parrots revealed 26 birds with microscopic evidence of excessive iron accumulation in visceral organs. Of these birds, hemochromatosis was diagnosed in 5% (13/264) based on the presence of excessive hepatic iron accumulation in conjunction with hepatic necrosis and was implicated as the cause of death in 3% (8/264) of birds. Liver iron levels in birds with hemochromatosis ranged from 1,600 – 3,800 parts per million (ppm), based on wet weight toxicological analysis. Affected birds ranged in age from three to 29 years old. In addition to the liver, iron deposits were identified histologically with Perl’s iron staining in the spleen (3/13), kidney (2/13), small intestine (1/13), lung (1/13), and ovary (1/13). Hemosiderosis, defined as hepatic iron accumulation in the absence of hepatic necrosis, was diagnosed in 5% (13/264) parrots and was associated with liver iron levels at or below 1,600 ppm based on wet weight analysis. Potential causes of hemochromatosis and hemosiderosis in Puerto Rican parrots include exposure to elevated iron in the diet or water sources, environmental exposure to other heavy metals such as zinc, chronic disease, or genetic susceptibility. Identification of the underlying cause may have management implications that could be beneficial to maximize individual survival in captive facilities. To the authors’ knowledge, this may be the first report of hemochromatosis in Puerto Rican parrots.