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Lead Poisoning

Overview


Lead poisoning is a serious sometimes fatal condition in chickens, caused by ingestion of small lead objects or lead-contaminated soil, while scratching outside. Since lead poisoning affects multiple body systems it often results in variable, non-specific clinical signs. Lead concentrations up to 300 ppm are considered "safe", however natural non-toxic levels are between 10-50 ppm.

Lead is a very dense metal and a strong neurotoxin. If ingested, since the metal is so dense and not easily oxidized, it will remain in the chicken's gastrointestinal tract, and slowly absorbed and released into the bloodsteam. Once in the bloodstream, lead will:
  • Damage red blood cells, interfering with their ability transport oxygen to other parts of the body (causing anemia).
  • Interfere with the chicken's ability to absorb calcium, which causes neurological problems.

Clinical Presentation


Lead poisoning can present in chickens as acute or chronic form, depending on the extent of exposure or quantity of lead ingested. When chickens ingest high amounts of lead in a short period of time it is called acute lead toxicity. Exposure or ingestion to small amounts of lead over a long period of time is called chronic toxicity.
  • Acute toxicity: Chickens that develop acute lead toxicity or poisoning will often present with sudden onset of muscle weakness, loss of appetite, marked weight loss, ataxia, drop in egg production and severe anemia.
  • Chronic toxicity: Chronic lead toxicity may eventually result in degeneration of motor nerves in the chicken's spinal cord and axonal loss in the peripheral nerves. Muscle atrophy and myodegeneration are often also present.

Common Sources of Lead


Common sources of lead exposure for chickens include:
Potential Toxic Lead Sources for Chickens
  • Contaminated soil: There are many ways that soil can become contaminated with lead. Soil located on the side of the road of busy streets is frequently contaminated with lead, since lead was an ingredient in gasoline until the late 1970s. Soil that surrounds older painted structures, as lead-based paint may still be in the soil adjacent the building. The land could also contain lead contaminated waste (batteries, asphalt products, leaded gasoline, lead shot, putty, and spent oil) which may be above or buried within the soil. Any vegetation that grows on the soil will be contaminated with lead, making the vegetation hazardous to chickens who frequently seek out forage to eat when free ranging in grass.
  • Contaminated water: Water can become contaminated with lead if it flows through old lead pipes or faucets--which was common during pre-1978 days.
  • Contaminated food: Food that is stored or left for long periods of time in ceramic glazed bowls or glass (especially for red and yellow shades), or imported from countries that use lead to seal canned food.
  • Tiny lead objects: There are many common everyday products that contain lead. If any of these are discarded or stored in areas where chickens have access, they can ingest it (especially if it is a small shiny object!). Lead-based objects include some toys, cheap jewelry, fishing equipment, hobby or sport objects (such as stained glass, paint, plaster, ink), and lead bullets for guns.
  • Building materials: Lead is used as architectural metals in roofing material, cladding, flashing, gutters and gutter joints, and on roof parapets.
  • Sound deadening materials: Sheet-lead is used as a sound deadening layer in the walls, floors, and ceilings of sound studios.

Additional Concerns for Humans


Lead poisoning also posses a threat to humans, especially young children, since lead is also deposited into the hen's eggs. Consumption of lead can cause brain damage, high blood pressure, miscarriages, and behavioral problems in children.

Risk Factors


The risk of lead contamination in a given environment varies depending on its history or prior use, geographic region, current use, age of structures, and how environmentally consciousness prior occupants of the land were.

Documented Lead Poisoning Cases in Poultry


AffectedHistoryClinical signsDiagnostic FindingsTests usedRef
Adult backyard chickenUnknownInability to stand, neck twisting, not eating or drinking, and death.Brain and gizzard koilin lesions.Necropsy; histopathologyCAHFS Connection, July 2013
Four 18-month-old chickens on a small farm in Auckland, New ZealandUnknownLoss of appetite and deathGastrointestinal stasis; Lead levels in the blood in one of the chickens was 0.24 mg/L (abnormal exposure level is greater than 0.2)Necropsy; Blood testNew Zealand Veterinary Journal, Quarterly review of diagnostic cases, April-June 2015
An adult chicken kept as part of a backyard flockThe owner of the flock was conducting renovations on the old structures on the property, which caused flakes of lead paint to scatter throughout the same yard that the chickens were grazing in.Swelling of crop and loss of appetite, followed by death.Blood lead levels were greater than 0.60 mg/L (normal is less than 0.4 mg/L)Blood testNew Zealand Veterinary Journal, Quarterly review of diagnostic cases, January to March 2016

Clinical Signs

Wing drooping
Incoordination (ataxia)
Difficulty standing
Aimlessly wandering
Stumbling
Twisted neck
Weakness
Green diarrhea
Twitching
Convulsions
Depression
Circling
Muscle atrophy
Lack of egg production
Weight loss
Loss of appetite

Diagnosis

  • History - known exposure
  • Clinical Signs
  • Blood test - blood lead levels above 0.2 ppm
  • Radiographs
  • Necropsy

Treatment

NameSummary
Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Calcium disodium edetate (CaEDTA)10-40 mg/kg injected intramuscularly (IM), twice daily. There should be a clinical improvement within 6 hours of initiating treatment.G Dumonceaux et al
D-Penicillamine (PA)55 mg/kg administered orally, twice daily; often used in conjunction with CaEDTAG Dumonceaux et al
Activated charcoalShould be administered orally, as a slurry with water in according with manufacturer instructions. For birds, the dosage is usually 2-8 g/kg body weightG Dumonceaux et al.
Removal of the metal objectIn cases where a chicken has ingested a lead object that is not passing, your veterinarian may need to remove the object from the chicken's gastrointestinal tract via endoscopy, surgery, or gastric lavage.

Prevention

  • Provide chickens their feed in feeders, and avoid scattering feed on the ground.
  • Test soil and water for lead concentrations
  • If chickens are enclosed in an outdoor run, prevent them from access the ground soil by elevating the floor using wood pallets, covered with large rubber mats (like those used for horse stalls).
  • Check exterior paint on old buildings and nearby structures as it can peel or flake off and contaminate the soil.

Scientific References

Risk Factors

  • Living in area with elevated amounts of lead in the soil
  • Previous use of area is unknown
  • Unsupervised house chickens
  • Soil surrounding old, painted structures such as houses, barns, tools sheds, etc.
  • Lead pipes or faucets used for water supply