Lead poisoning is caused by the ingestion of lead from many different sources such as:

  • Discarded lead batteries.
  • Lead-based paint.
  • Vehicle sump oil.
  • Old machinery and cars parked up in farms.

    • While all ages can be affected by lead poisoning, it is most commonly seen in curious calves.

    Cases tend to peak early in the summer when cattle first get turned out to grass. Another risk is car batteries or other forms of lead becoming ensiled in silage and fed out to livestock during the winter. It has been noted that there are more outbreaks in the years subsequent to very hard winters, where batteries lying around may burst as a result of the freezing weather.

    Symptoms

    Lead poisoning tends to cause sudden death in calves while clinical signs may last longer in older cattle. There is usually a sudden onset of nervous signs including depression, blindness or frothing at the mouth. Other symptoms include champing of the jaw, muscle tremors, staggering and convulsions, head pressing or a dummy-like syndrome. In many cases, animals are found dead.

    Lead poisoning can often be diagnosed on clinical signs and finding a source of lead to which the animals had access.

    Treatment

    Farmers are urged to contact their vet if they suspect a case of lead poisoning on the farm. However, treatment is rarely successful.

    Prevention and control

    From a public health perspective, lead exposure in milking cattle or beef cattle being readied for slaughter has potential risks for the food chain, as well as having a severe financial impact on the farmer. Herds may be restricted, the beef and milk kept out of the food chain until such time as the lead level of the produce is known to be considered not to pose any risk to consumers. Obviously this could have considerable implications for the farmer involved, resulting in considerable losses. Therefore prevention of lead poisoning is the best policy.

    Prevention is a matter of not allowing cattle access to the sources of lead.

  • Dispose of all lead batteries carefully according to Local Authority guidelines. Prior to disposal, ensure that batteries are kept where cattle can’t access them or where they or their leaked contents can’t end up in silage or in a diet feeder.
  • Ensure cattle do not have access to old cars or tractors or leakage from batteries or sump oil.
  • Before cattle are turned out to grass in the spring and at regular intervals during the grazing season, search the fields for discarded batteries, lead shot or other possible sources of lead. This is especially important in fields bounded by a public road where illegal fly-tipped material may be a potential risk to grazing animals.
  • Do not use timber painted with old toxic lead paints, like an old painted door to block a gap or doorway, or leave them in areas that are accessible to cattle, especially calves which have a tendency to lick such items.
  • Do not use lead pipes for plumbing, or red lead paint for preserving metalwork.