Lead Alert - Poisoning in Cattle

Analysis of SAC data for the past 5 years shows that 92.5% of lead poisoning cases were diagnosed between April and September i.e. during the grazing season.  Of these almost three quarters occurred in May and June.  In other words the time of greatest risk is the period immediately following turn out.  The vast majority of cases (92.5%) involved animals aged 2 years or less with animals under a year accounting for half of these.  

Spring would therefore be a good time for farmers, stockmen and herdsmen to inspect fields before cattle, especially young stock, are turned out.  

You should particularly check for lead batteries which are a common source of toxicity.  These may have appeared as a result of fly tipping or been overlooked following use of an electric fence.  Sites of burnt out vehicles and bonfires (where batteries have been added) are also dangerous.  To make these safe remove the ash plus a layer of soil.  Lead paint and geochemical lead (present naturally in the soil) are less common causes of toxicity.  

Lead is ingested because young cattle are inquisitive and the electrolytes in batteries can be palatable.  Following absorption lead competes with calcium affecting the CNS, neuromuscular transmission and bone.  Acute toxicity can occur within 24 hours and signs range from sudden death to blindness, ataxia, convulsions and hyperaesthesia.  Animals that survive for a few days are dull, blind, anorexic, have abdominal distention and may become recumbent.  

Differential diagnosis include CCN, meningitis and other toxicities e.g. closantel.  

Blood samples would be required for diagnosing a suspected poisoning in a live animal.  For suspected poisoning in a dead animal then the liver and kidneys are the best tissues to collect as lead is excreted by them.

In order to protect the human food chain cases of lead poisoning are reported to Food Standards Scotland or the Food Standards Agency in England and Wales as appropriate.    

Reference:

Payne, J. & Livesy, C., (2010) Lead poisoning in cattle and sheep.  In Practice, 32, 64-69.

Related SEV Branch