Public health implications of lead poisoning in backyard chickens and cattle: four cases

Abstract

Lead intoxication in livestock has historically been associated with cattle turned out to pasture and accidental ingestion of lead from drinking crankcase oil, licking grease from machinery, chewing on plumbing or batteries, or drinking water contaminated from leaching materials. Even with the decrease in manufactured items produced with lead, contaminants persist in the landscape and may enter the food supply through animal products. Changing patterns of open range herds moving to new pasture and the increased popularity of urban/suburban backyard chickens or other livestock necessitates public awareness about the clinical signs of lead intoxication, the potential for subclinical animals, public health concerns, particularly for exposure in children, and testing options available. Cases of lead intoxication in livestock demand a thorough case work-up to identify all sources of lead, address subclinical cases, evaluate risk to consumers, and make management suggestions for future prevention. We discuss four recent cases of confirmed lead poisoning in backyard chickens and open range cattle and assess the public health implications therein. Taken as a whole and considering the potential of the remaining herd or flock to be affected without necessarily showing signs, public health officials and veterinarians should be prepared to advise clients on case work-up and management and prevention considerations. Backyard chickens and cattle may not present for suspected lead poisoning as in several of the cases discussed herein yet may still contain concerning tissue or blood levels. The authors believe increased surveillance through heavy metal screens is crucial to adequately protect public health.

Content of Toxic Elements (Arsenic, Cadmium, Mercury, Lead) in Eggs from an Ethically Managed Laying Hen Farm

“…The highest lead content was found in chickens' bones followed by the kidneys and liver, while the lowest content was found in the skeletal muscle [17]. Clinical signs of acute lead poisoning in chickens include muscle weakness, ataxia, and loss of appetite, followed by marked weight loss and the cessation of egg production [20].…”