Clinical testing and treatment advice for vets responding to lead poisoning
In cases of suspected lead poisoning, samples that should be submitted for analysis - where possible - include:
- suspected sources of lead
- clotted blood and faeces from live animals
- unpreserved liver and kidney from dead animals
- preserved liver or kidney
- blood samples containing ethylenediaminetetraacetic acid (EDTA) and a blood smear - may also assist with differential diagnosis.
Clinical lead poisoning in adult ruminant animals is associated with lead levels of more than 10mg/kg in liver or kidney, but fatal poisoning can occur with lower tissue levels.
The Australia New Zealand Food Standards Code sets maximum levels for lead:
- in edible offal of cattle, sheep, pig and poultry at 0.5mg/kg
- in meat (excluding offal) at 0.1mg/kg.
For cattle, a normal blood level of less than 0.24µmol/L (less than 0.05mg/kg) has been adopted across Australia to assist in determining if lead residue levels could pose a food safety risk.
Treating lead poisoning
Treatment of animals with lead poisoning may not be successful if the animals have extensive tissue damage, especially if the damage is in the nervous system.
Animals receiving treatment must be under the care of a veterinary surgeon and treatment may take several days. Animals are usually treated with an intravenous injection of calcium versenate as a chelating agent.
It is important to provide supportive therapy, including fluids and sedatives, to combat convulsions.
Managing food-producing animals containing unacceptable levels of lead
Cattle with elevated blood levels of lead and untested animals in exposed herds or mobs must be excluded from slaughter to ensure that there is no food safety or trade risk from food products derived from exposed animals.
Detained livestock must be permanently identified with an approved device, such as a National Livestock Identification System (NLIS) device. These animals are assigned a residue status to alert processing establishments about potential contamination issues
Contact the Customer Service Centre for a copy of the policy for managing food-producing animals that have been diagnosed with lead poisoning, have elevated blood lead levels or have been at risk of exposure to a lead source.