Causes and signs of lead poisoning and contamination in production animals

Animals may find material contaminated with lead in silage, rubbish dumps and around farm buildings and machinery. Lead can be present in:

  • discarded sump oil and oil filters
  • lead batteries (the most common cause of cases)
  • flaking lead-based paint or old paint tins
  • lead shot and fishing sinkers
  • linoleum, grease, putty, metallic lead
  • other sources.

Animals are likely to seek out sweet-tasting lead compounds if they are bored from being confined or have changed appetites from malnutrition or phosphorus deficiency.

The easiest and most effective way to protect your production animals from lead poisoning and contamination is to dispose of lead safely. Never dispose of toxic waste in general rubbish dumps or bins. Local councils usually provide options for toxic waste disposal. Local garages may dispose of sump oil and car batteries for you, and some scrap metal merchants will purchase lead batteries.

If your animal is showing signs of lead poisoning you should:

  • provide the animal with food, water and shade
  • keep the animal separate from other animals
  • try to identify and remove the hazardous material from your property
  • collect a sample of the hazardous material for analysis
  • contact your veterinarian.

Signs of lead poisoning in production animals

Symptoms vary according to the degree of poisoning, but animals may show a combination of gastrointestinal and nervous signs. Gastrointestinal signs may include either constipation or diarrhoea.

Acute lead poisoning

In cases of acute lead poisoning, animals may be found dead or they may display combinations of several signs for a few hours before death. These signs may include:

  • colic
  • staggering gait
  • rolling eyes
  • slobbering
  • muscle spasms
  • blindness
  • uncoordinated attempts to climb obstacles
  • excessive response to external stimuli
  • head pressing
  • convulsions.

Subacute lead poisoning

In cases of subacute lead poisoning, animals may display signs such as:

  • dullness
  • loss of appetite
  • abdominal pain
  • diarrhoea.

Chronic lead poisoning

In cases of chronic lead poisoning, animals may be found dead or display signs such as:

  • symptoms of acute poisoning – see above
  • loss of appetite
  • wasting
  • anaemia
  • constipation
  • recumbency
  • difficulty breathing.

Diseases with symptoms similar to lead poisoning

Other diseases that can cause nervous system signs that are similar to lead poisoning include:

  • tick fever – cerebral babesiosis
  • nutritional and metabolic deficiencies – hypomagnesaemia, ketosis, thiamine deficiency, vitamin A deficiency
  • other types of poisoning – mercury, organophosphates, organochlorines
  • plant poisoning – Noogoora burr, pyrrolizidine alkaloid poisoning
  • enterotoxaemia – Clostridium perfringens type D
  • viral infections – infectious bovine rhinotracheitis (IBR), sporadic bovine encephalomyelitis (SBE), and bovine malignant catarrh (BMC)
  • bacterial infections – listeriosis.

The general biosecurity obligation

If you are dealing with food-producing animals, you are bound by a general biosecurity obligation under the Biosecurity Act 2014. This obliges you to minimise the risk posed by conditions such as lead poisoning and contamination in your animals. Fulfilling the obligation includes correctly disposing of waste materials that contain lead, and ensuring that food-producing animals that come into contact with lead are dealt with appropriately.