Bleiintoxikationen bei freilebenden Seeadlern (Haliaeetus albicilla)
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Beschreibung
Lead intoxication in free-ranging white-tailed eagles (Haliaeetus albicilla)
The aim of this study was to evaluate medical data from German white-tailed eagles with diagnosed lead poisoning based on clinical signs, diagnostic imaging and laboratory diagnostic findings. From August 1998 to January 2020 238 free-living H. albicilla were presented at the Small Animal Clinic of the Freie Universität Berlin. Inclusion criterion was a blood lead concentration of 0.4 ppm, typical clinical symptoms associated with lead intoxication and absence of any other clinical findings. Based on these, data of 73 free-living white-tailed eagles were included in this study. The majority of eagles originated from Brandenburg (44/73), followed by Mecklenburg Western Pomerania (14/73), Saxony (6/73), Schleswig Holstein (4/73), Saxony Anhalt (3/73) and Berlin (2/73). Most of the birds were found in autumn and winter months (October to March) (60/73, 82 %). The most common age group were adult white-tailed eagles (50/73, 69 %), followed by immature (17/73, 23 %) and juvenile birds (4/73, 5 %) as well as nestlings (2/73, 3 %). Female white-tailed eagles (40/73, 55 %) were presented more often than males (30/73, 41 %). Typical clinical findings could be evaluated in 72 out of 73 birds including apathy (72/72, 100 %), dyspnoea (50/72, 68 %), poor nutritional status (44/72, 60 %), biliverdinuria (35/72, 48 %), vomiting (23/72, 32 %), crop stasis (21/72, 29 %) and neurological signs (19/72, 26 %). Metal-dense fragments within the digestive tract were detected in 44 % of the birds during radiological examination (32/73). Those were most frequently located in the stomach, followed by intestines and crop. In 12 % of the white-tailed eagles, metal-dense fragments were furthermore found outside the digestive tract (4/34). Hemolysis was observed in the plasma of 62 % of all birds examined (45/73). The median blood lead concentration was 3.0 ppm (min=0.4 ppm; max=21.7 ppm). Significantly higher blood lead concentrations were found in white-tailed eagles presenting with biliverdinuria (rs=0.44; p=0.002), dyspnoea (rs=0.38; p=0.001), and metal dense fragments located within the digestive tract (rs=0.3; p=0.009). Furthermore, higher blood lead concentrations were significantly more common in adult white-tailed eagles (rs=0.25; p=0.03) than in other age groups. Hematological examination of white-tailed eagles revealed anemia in 26 % of the birds (18/73). The greatest deviations from reference intervals in blood biochemistry parameters were observed in aspartate aminotransferase and creatine kinase activity as well as in glucose concentration. Therapeutic endoscopy was attempted in 59 % (16/27) of white-tailed eagles with metal-dense fragments located in the stomach. Lead fragments were successfully retrieved in 69 % (11/16) of birds, but despite endoscopic treatment 13 of 16 white-tailed eagles died due to lead intoxication. Blood lead concentration could be continuously reduced with intramuscular administration of Ca Na2 EDTA at 50 mg/kg BW BID, at 100 mg/kg BW BID or Ditripentate at 50 mg/kg BW SID. Overall, 79 % of the white-tailed eagles (31 females, 25 males and two unknown sex) presented died as a result of lead poisoning. Factors that significantly influenced the prognosis were the presence of dyspnoea (r=0.63; p=0.001), biliverdinuria (r=0.43; p=0.005), blood lead concentration (rs=0.36; p=0.002) as well as hemolysis (r=0.31; p=0.01). A survival tree analysis indicated that dyspnea was the most relevant factor for assessing the prognosis of white-tailed eagles with lead intoxication followed by the presence of anemia. White-tailed eagles with dypnoea had a 6 % survival rate, while the chance of survival of birds with anemia was 24 %.
Postmortem liver lead concentrations of white-tailed eagles were higher than kidney lead concentrations (rs=0.8; p=0.001). 74 % (34/46) of the birds showed significantly increased liver lead concentrations while 24 % (11/46) had increased kidney lead concentrations (>8 ppm). In 86 % of the white-tailed eagles dying with blood lead concentrations of less than 1 ppm (6/9), liver lead concentrations higher than 1 ppm were detected.
To the author’s knowledge this is the first study evaluating the course of lead intoxication in a larger number of white-tailed eagles. The results of this study should therefore help to better assess the prognosis of lead intoxication in this species and treat affected birds accordingly.
Autor*in
Lesley Halter-Gölkel
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Eagles predatory birds lead lead poisoning symptoms clinical examination anaemia liver toxicity