Cattle Farmers Should be on the Look Out for Lead Poisoning

"With cattle due to be turned out to pasture, farmers should be on the look out for lead poisoning symptoms," says SAC Vet Colin Adams.

"Poisoning by lead is still the most common cause of poisoning in

cattle. Although outbreaks can occur at any time of the year, both inside and outside, the peak time of the year for incidents is from April to July. Calves are more susceptible than adults, with suckler calves

particularly susceptible."

Food producing animals that have been exposed to substances such

as lead, that if transferred to animal products such as milk or meat, can be potentially hazardous to humans are subject to the Food Safety Act (1990).

The most common factor in lead poisoning incidents is access to

rubbish with common sources including old, flaking, lead based paints, lead batteries, discarded sump oil, grease, putty and linoleum. Before turnout it is a good idea to have a walk round the boundaries of all the

fields that turned out cattle will have access to. Any rubbish or identified hazards should be removed or fenced off. Used motor oil should be placed in sealed containers and farm machinery should be serviced away from animals.

There have also been incidents of lead poisonings in grazing animals where high concentrations of lead in the soil have been implicated – mostly seen in areas where lead has been mined.

Cattle, and especially calves, are naturally inquisitive and have a tendency to lick novel objects meaning that a toxic dose can soon be ingested. Poisoning can result from a single ingestion of a toxic amount or from a continued ingestion of lead from the environment.

What to look out for

The onset of the disease and, to some extent, the clinical picture that develops depends on the dose of lead ingested.

* Acute cases follow ingestion of a large quantity of lead and clinical signs develop rapidly with neurological signs such as apparent blindness, head pressing, frothing, teeth grinding, fits, and muscle tremors all being apparent. Sudden death is also common.

* Subacute cases take longer to develop and animals may be dull, with loss of appetite, ruminal stasis resulting in constipation followed by diarrhoea, and may also be apparently blind.

* Chronic cases are rare.

Diagnosis and treatment

Other diseases and poisons may show clinical signs similar to lead poisoning. If cattle show signs that suggest lead poisoning, farmers should call in their veterinary surgeon. If cattle die suddenly they

should arrange to submit the carcase to their local SAC Disease Surveillance Centre for post mortem examination.

Treatment has to begin early if an animal is to be saved and will

normally involve supportive and symptomatic treatments and

intravenous injections of lead chelating agents.