Choroidal Vasculopathy and Retinal Detachment in a Bald Eagle (Haliaeetus leucocephalus) With Lead Toxicosis

Abstract

A subadult male bald eagle ( Haliaeetus leucocephalus ) was presented for severe depression and weakness. Physical examination findings included depressed mentation, dehydration, sternal recumbency, poor body condition, and bilateral, whole-head, horizontal nystagmus. A heavy-metal panel was performed, and blood lead levels were 6.1 ppm. Treatment for lead poisoning was initiated, including subcutaneous fluids and parenteral calcium-disodium ethylenediaminetetraacetic acid, ceftiofur, and meloxicam. Ophthalmic examination findings included absent menace response, absent dazzle reflex, slow and incomplete direct pupillary light reflex, mild anterior uveitis, incipient cataracts, multifocal retinal tears, and retinal separation in both eyes. Because of poor prognosis for vision and release to the wild, the eagle was euthanatized. No lesions were observed on gross postmortem examination. Histologically, extensive myocardial necrosis and multisystemic arteriolar vasculopathy were identified. The eyes were examined after tissue processing, and the vasculopathy extended into the choriocapillaris and was associated with a secondary, bilateral, exudative, retinal detachment. This is the first report in avian species characterizing the histopathologic ocular lesions of lead poisoning.

Effects of lead from ammunition on birds and other wildlife: A review and update

“…Several recent studies have reported sub-lethal effects of lead in wild birds, supplementing earlier research. A histopathological study of the eyes of a bald eagle provided the first evidence of ocular lesions associated with sub-lethal but extremely elevated blood lead levels (c. 610 µg/dl—Eid et al 2016). The prognosis for this rehabilitated bird’s vision was too poor for it to be released back to the wild.…”

Lead Intoxication in Free-Ranging Bald Eagles (Haliaeetus leucocephalus)

“…A multisystemic fibrinoid necrosis of arterioles has previously been described in a bald eagle with lead toxicity. 8 It is unknown whether the preferred involvement of cardiac, neural, and ocular arteries in the current study may indicate an increased sensitivity of these vessels to lead. This selective vascular injury does not appear to be directly associated with the amount of blood flow, as renal arterioles would be expected to be frequently affected if that were the case.…”

“…With the exception of 1 previous study ( n = 484 bald eagles), 11 reports of lead intoxication–associated lesions in bald eagles have otherwise been limited to small case numbers ( n = 1–6). 6,8,13,23,29…”

The use of sulfur hexafluoride microbubbles for contrast‐enhanced ocular ultrasonography of the pecten oculi in birds

“…Structural detail of the pecten oculi has been elucidated in anatomical studies using scanning electron and light microscopy . However, advanced diagnostic imaging investigations (ie, optical coherence tomography—OCT) may better help to understand the precise role of the pecten oculi in normal ocular health and in disease pathogenesis . Ultrasonography (US) is a widely available, quick, and noninvasive imaging technique with multiple modalities (eg, color and pulsed Doppler ultrasonography; D‐US) that has been successfully used to investigate the pecten oculi .…”

“…10,15,22,23 However, advanced diagnostic imaging investigations (ie, optical coherence tomography-OCT) may better help to understand the precise role of the pecten oculi in normal ocular health and in disease pathogenesis. [24][25][26][27] Ultrasonography (US) is a widely available, quick, and noninvasive imaging technique with multiple modalities (eg, color and pulsed Doppler ultrasonography; D-US) that has been successfully used to investigate the pecten oculi. 7,8,28 Physiologic parameters for resistive and pulsatility indexes of the pectinate artery have been investigated using D-US in both American Pekin ducks (Anas platyrhynchos domestica) and harpy eagles (Harpia harpyja).…”