Lead poisoning in cattle is appearing more often on the Prairies.
Barry Blakely’s laboratory at the University of Saskatchewan is seeing up to a fourfold increase in cases this year.
“Farmers can put an end to this right now. They have to clean up old batteries and avoid putting any more out into places where cattle will find them,” said the scientist.
“This year it’s been three or four herds a week, from Saskatchewan and Alberta mainly,” he said.
Normally, there is surge in lead poisoning cases during spring seeding and fall harvest. When hurried farmers replace batteries in the fall or winter, the old batteries freeze and crack and cattle lick the lead salts they contain. Old battery piles are forgotten or even unknown to new landowners or renters. Cattle, possibly suffering a mild case of mineral deficiency coming off a long winter or dry summer feeding season, can make a tasty discovery.
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“Then they die. A few get a lethal dose and die while other get exposed to lesser levels that still exceed what is safe,” Blakely said.
That is when lead poisoning from used batteries shifts from a livestock loss to a food safety problem.
It takes years for lead to dissipate. For all practical purposes, lead toxicity is a permanent condition for cattle. Research at the U of S has shown that if poisoned cattle survive, lead remains present in their tissues from seven to 10 half lives of the metal. Each half life is 300 days.
“Then the other lead poisoning needs to happen,” said Blakely.
“You can lose $1,000 on the cow now, or $1,200 if you keep putting feed in her and have to euthanize her or have her die later,” he said.
There are no effective treatments for lead poisoning in cattle. A drug once available to pull lead from blood is no longer on the market. A pharmacist can mix up the compound but without registration, the withdrawal times are a tricky issue, said Chris Clark of the Western College of Veterinary Medicine in Saskatoon.
“I would personally be very reluctant to eat an animal that was treated for lead poisoning.”
Lead accumulates in the organs and bones, but is also present in blood and muscle tissue.
The Canadian Food Inspection Agency regularly tests meat for lead content.
In 60 percent of the cases that the U of S lab sees, it is a calf that has died. Calves form only about 25 percent of the population and are disproportionately affected.
“They are more curious and they get into batteries more often. We know children are more vulnerable to the effects than adults, so it could have something to do with that,” Blakely said.
For human children, lead is extremely damaging to development, say researchers. The Canadian Prairies have significantly lower environmental lead levels than many North American regions, but they lead the way in lead poisoning of livestock.
“It’s up to 10 times more common in Saskatchewan than in any other state or province,” said Blakely.
“We’ve seen it in herds of 10 outside Saskatoon and in Alberta in a herd of 300 where the whole herd was destroyed. It’s really sad for the producer. It can be a terrific loss to the individual. To the beef industry there can’t be any room for failing to deal with a poisoning though.”
Clark said it’s an unfortunate situation for producers.
“Each time we get a clinical case, we ask if there are any batteries that animals could have gotten into. And every time we’re told there are no batteries in the pasture. But in the autopsy we pick chunks of lead battery out of the rumen,” he said.
“Farmers need to make a thorough investigation before they have a loss.”
Researchers say disposal of the carcass should be done in a manner that prevents scavengers from coming into contact with the metal.
On the Prairies, 95 percent of the incidents of lead poisoning involve beef cattle.
Symptoms can be similar to polio or rabies and include loss of appetite, depression, staggers, mania, convulsions, blindness, circling, twitching, tremors and death.
Clark said sulfate poisoning is also a problem this year as dugouts and sloughs are drying up, concentrating the minerals.
“If calves present with the symptoms, we test for lead. There isn’t a test for sulfates because the two problems look so similar,” he said.
