June 1, 2012 09:00
Dr. LeeAnn Forsythe DVM, MVetSc, Disease Surveillance Veterinarian
Lead poisoning continues to be the most predominant toxicity encountered in cattle and a cause of significant economic loss for beef and dairy producers. Currently, the primary source of lead on the prairies is discarded vehicle batteries.
Symptoms of lead poisoning in cattle include neurological signs such as depression, stumbling or difficulty walking, blindness, and seizures. The most severely affected animals die within 24 hours of initial onset of clinical signs, but some animals may die up to 2 weeks after exposure. Not all animals exposed to the lead will develop clinical signs; some may appear to be perfectly normal even though the level of lead in their blood is high. The only way to be certain of which animals were exposed to lead is to test blood for lead.
Because lead is heavy, pieces of lead can become stuck in the cow’s stomach. These pieces slowly release lead into the cow’s body over a long period of time. Lead is deposited in the kidneys, liver, and bone and excreted in the milk, urine and feces. The time to elimination from the body is highly variable. In some cases animals have found to have lead levels above the acceptable limit for years after the exposure.
Livestock producers need to ensure that cattle do not have access to lead by removing discarded batteries, old oil, paint, shingles and other sources of lead. Meat and milk from lead-poisoned cattle is a food safety concern; therefore, these animals should never be used for food production