Lead poisoning in cattle raises food safety concerns

Lead poisoning is identified as a significant and common toxicological issue affecting cattle herds in Western Canada, with potentially devastating consequences for producers. The problem frequently arises when cattle are turned out onto pastures, particularly in the early grazing season, and consume lead from discarded batteries, which are appealing due to their salts. Symptoms in affected animals can include neurological issues like blindness, inco-ordination, head pressing, seizures, and in severe cases, sudden death. A study published in the Canadian Veterinary Journal, covering cases submitted to Prairie Diagnostic Services from 2014 to 2024, documented 233 cattle herds experiencing confirmed lead poisoning, with samples from 352 cattle showing high lead levels. Outbreaks varied annually, peaking in 2018 with 36 affected herds. The majority of herd outbreaks occurred in May, June, and July. Recent pasture changes were frequently noted in case histories, and distressingly, six herds experienced multiple years of lead poisoning. Calves under four months of age were most frequently affected, likely due to their curiosity and higher absorption rates. A critical concern highlighted is that animals which consume lead but do not show clinical signs can still pose a food safety risk if they enter the food chain. The study emphasizes the importance of testing blood lead levels in entire groups if lead poisoning is diagnosed in an individual animal, as the half-life of lead in blood can be highly variable. Veterinarians are advised to test animals for lead if sudden deaths or neurological signs are observed on pasture. In Alberta, lead poisoning is a reportable disease.