The effect of lead poisoning on hematologic and biochemical values in trumpeter swans and Canada geese

BACKGROUND: Lead is a persistent contaminant in the environment, and waterfowl are susceptible to lead toxicity from ingestion of lead pellets and fishing weights. Lead affects numerous physiologic processes through inhibition of enzyme activity and protein function, but its effects on commonly assessed avian blood values are incompletely understood. OBJECTIVES: Our aim was to evaluate hematologic and biochemical changes associated with blood lead concentrations in trumpeter swans and Canada geese. METHODS: Data for CBCs, plasma biochemical profiles (total protein, albumin, glucose, cholesterol, total bilirubin, calcium, phosphorus, gamma-glutamyltransferase [GGT], aspartate aminotransferase, lactate dehydrogenase, glutamate dehydrogenase, creatine kinase, amylase, and lipase), and whole blood lead concentrations were retrospectively analyzed for 69 trumpeter swans and 52 Canada geese. Laboratory data obtained prospectively from an additional 20 trumpeter swans also were included. RBC morphology was semiquantitated in blood smears from 70 of the birds. Data were analyzed initially by ANOVA and covariance. A statistical model then was constructed to determine the relationship between each parameter and lead concentration. RESULTS: In both avian species, PCV, hemoglobin concentration, and MCHC decreased significantly (P < .05) with increasing blood lead concentration. Uric acid concentration and GGT activity were increased in trumpeter swans and phosphorus concentration was decreased in Canada geese in association with high blood lead concentration (P < .05). CONCLUSIONS: Lead toxicosis induced significant changes in the values of commonly measured hematologic parameters in waterfowl. These changes may be useful indicators of severe lead intoxication during routine laboratory assessment. Changes in clinical chemistry values, although statistically significant, were too inconsistent to serve as indicators of lead toxicosis.     

Lead concentrations in the blood and eggs of backyard laying hens

AIMS: To investigate the prevalence of lead exposure in hens and eggs from backyard poultry in a sample of Auckland households, the relationship between concentrations of lead in the blood of the hens and in the shells and yolks of eggs from the same household, and to examine associations with measures of hen health, environment and husbandry factors.

METHODS: Thirty households participated in the study from August to November 2016, each providing one adult hen for sampling, an egg from the household if available, and completing a questionnaire on hen husbandry. Concentrations of lead in blood were determined using a portable lead analyser. Eggs were analysed for concentrations of lead in the yolk and shell using inductively coupled plasma mass spectrometry after biological digestion with a mixture of nitric and hydrochloric acid.

RESULTS: Twenty three of 30 hens (77%) showed evidence of lead exposure, with median concentrations of lead in blood of 0.77 (min?<0.16, max 8.02) μmol/L. All eggs showed evidence of lead exposure, with concentrations of lead in the yolk ranging from 0.003–1.07?mg/kg, and concentrations of lead in the eggshell ranging from <0.1–0.82?mg/kg. A positive correlation existed between concentrations of lead in the blood of a hen and concentrations of lead in egg yolk from the same hen (R²=0.97), and both the yolk (R²=0.58) and shell (R²=0.30) of an egg from her flock. No association was found between concentrations of lead in blood and hen health indices measured in this study. Concentrations of lead in blood were higher in hens from properties with homes built before 1941 than between 1941–1960 (p=0.03), and in hens from properties with weatherboard homes than brick homes (p=0.049).

CONCLUSIONS AND CLINICAL RELEVANCE: There was a high prevalence of lead exposure in this sample of Auckland backyard chickens, with the majority of hens being sub-clinically affected. Associations were found between concentrations of lead in the blood of the hens, and properties with homes built before 1941 and clad in weatherboard. Concentrations of lead in over half the egg yolks sampled were at levels sufficient to warrant human health concern. The assessment of concentrations of lead in backyard poultry and eggs intended for human consumption is recommended to protect human and bird health.