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Cases of lead poisoning most commonly occur when cattle are turned out onto pasture in the spring and early summer.
The main source of lead poisoning in cattle are improperly disposed batteries from automotives and farm machinery.
The best prevention is to walk your pastureland and identify and remove any batteries or parts of batteries found.
Human health standards are strict and do not allow any lead-poisoned animals into the food supply chain.
Lead poisoning is diagnosed in several beef cattle herds each year. Although not common, lead poisoning is devastating to herds that are impacted and has been the leading cause of poisoning in beef cattle for several decades.
What are the sources of lead for beef cattle herds?
Discarded batteries from machinery like cars and tractors are the main culprits for lead poisoning in beef cattle. This is particularly an issue when batteries have remained on a pasture for many decades, which allows for the outer battery casing to be broken down, leaving sheets of lead exposed. Cattle will readily consume the exposed sheets as the flavor is palatable to them.
Cases of lead poisoning most commonly occur when cattle are turned out onto pasture in the spring and early summer and cattle of all ages are vulnerable.
Unfortunately, it doesn’t take much lead to be lethal, and with up to 9 kg of lead in a typical battery, there is enough lead in one battery to cause serious health issues in many individual beef cattle.
Photo of disintegrating lead acid battery courtesy of Alberta Agri-News
As long as battery casings remain intact, cattle are unlikely to be able to access the lead inside. Periodically checking any batteries being used on pasture for fencing or water pumps to ensure they aren’t cracked or damaged will protect cattle from potential exposure.
Other possible sources of lead include lead-based paints on old buildings and vehicles and old engine oil. Taking into account where sources of lead may be and removing or keeping cattle away from those sources helps ensure your herd is not exposed.
What are the symptoms of lead poisoning in beef cattle?
Cattle are vulnerable to lead poisoning in all life stages. Lead poisoning affects the brain resulting in a collection of symptoms that are often referred to as polioencephalomalacia (PEM) or “polio.” These symptoms include:
Blindness
Excessive drooling
Grinding teeth
Wandering, circling or head pressing
Abnormal behaviour (e.g., alone in pasture, standing in an odd location, agitated, excessive bellering)
Tremors in ears, face or eyes
Grand mal seizures
Death
However, there are other causes of PEM, which could make reaching a poisoning diagnosis difficult. This includes sulfur and salt poisoning (from marginal quality water or dried up water sources) and thiamine deficiency. The time of the year will provide context clues for what is going on. If you are noticing these symptoms in early spring or summer, or immediately after a move to a new pasture, lead could be a likely culprit.
Contact your veterinarian immediately if lead poisoning is suspected so that a thorough diagnosis can be made through post-mortem sampling or blood tests. Cattle that have come into contact with lead should not enter the food chain, so definitive diagnostic testing is important.
How is lead poisoning diagnosed?
Samples collected from cattle by the veterinarian are sent to a diagnostic laboratory. In deceased animals, liver or kidney samples can be sent for diagnostic testing. In live animals, whole blood can be submitted. However, the quickest way to identify suspected lead poisoning in deceased animals is to look in the rumen to determine if pieces of lead can be seen.
Want to learn more about lead poisoning in Canadian beef herds? Check out the Beef Cattle Health and Nutrition Podcast episode on lead toxicity in cattle featuring Dr. Vanessa Cowan.
I think I have cattle with lead poisoning. What now?
Identify the source of lead and prevent further access. If the source cannot be found, move cattle to a different pasture.
Call your veterinarian. Cattle with severe symptoms of poisoning should be euthanized. Postmortem exams are important for the collection of diagnostic samples but also to check for lead particles in the rumen.
In many provinces, lead poisoning is a reportable disease. The chief provincial veterinarian should be contacted by your veterinarian if lead poisoning is confirmed.
Some cattle that have been exposed to lead may not show symptoms. All potentially exposed cows should be tested for exposure through a blood sample as no animals who have ingested lead are allowed to be sent to processing.
Is there a treatment for lead poisoning?
There is no practical treatment for lead poisoning in cattle. Lead remains in the body of a cow for a long period of time – months to years. Cattle exposed to lead will have to be periodically tested to check the concentration of lead in their blood.
PREVENTION
The best prevention is to walk your pastureland and identify and remove any batteries. Rigorous monitoring of pasture is necessary, as in many cases batteries or other sources go unnoticed until cattle begin showing signs of poisoning. Areas of highest concern including old dump piles, pits, old vehicles and piles of metal plates should be fenced off to prevent access to cattle.
Dead or found batteries should be disposed of properly. It is important that they do not end up in the trash or landfill due to the hazardous materials they contain. Instead, batteries should be recycled at a designated recycling center, a local auto parts store or participating retailer. It is important to check your local regulations as some municipalities have specific rules or potentially support collection programs.
Remove all potential sources of lead from pastures or do not allow cattle access to areas where lead may be.
Photo of disintegrating lead acid battery courtesy of Alberta Agri-News
Can cattle exposed to lead be eaten?
While it is extremely unlikely that people will become poisoned by eating meat from a lead-poisoned animal, human health standards are strict and do not allow any lead-poisoned animals into the food chain. Protocols on how to manage lead-poisoned cattle vary by region. Consult with your veterinarian if there is any suspicion of lead toxicity for best management practices.
Consultation with toxicology expert Dr. Vanessa Cowan in March 2025
Acknowledgements
Thanks to Dr. Vanessa Cowan, DVM, for sharing her expertise on this topic. If you have questions regarding lead poisoning in cattle, please reach out to Dr. Cowan at [email protected].
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