A plan to poison the wild hogs of Texas
They say everything is bigger in Texas. And certainly, the saying holds true for the state’s feral hog population. At 2.5 million it’s the nation’s largest, and is growing exponentially as the sows birth litters of five to six piglets twice a year and those piglets can start reproducing before they are even a year old.
Brought to Texas by Spanish explorers in 1542, wild pigs here cause an estimated $52 million a year in damage as the bristly backed hooligans smash through fences, decimate crops, eat baby livestock, dig up Internet and water lines, ruin golf courses and cause car accidents when they dart across the road. They also carry diseases that have the potential to devastate cattle and domesticated pig operations, as well as infect humans.
And so the state’s agriculture commissioner, Sid Miller, who made his name in the State Legislature sponsoring the “pork chopper bill” allowing Texans to shoot wild pigs from helicopters, now wants to use chemical warfare to bring about what he calls the “feral hog apocalypse.” The poison? Warfarin (a.k.a. Coumadin), the most commonly prescribed anticoagulant, or blood thinner, for humans.
His department issued an emergency rule in February fast-tracking the use of warfarin-laced bait, sold under the brand name Kaput Feral Hog Bait. The rule stipulated that, at least initially, sale and distribution of the product, which was approved by the Environmental Protection Agency a month earlier, be limited to licensed pest control professionals. “I didn’t want some yahoo getting a 50-pound bag and dumping it on the ground,” Miller said.
Texan hunters, who smear on face paint and wear night-vision goggles to track and take out the nocturnal pigs by land and by air, have pushed back, convincing a state district judge in March to issue a monthlong restraining order against use of the warfarin bait. They also lobbied for a bill calling for more testing, which has passed the Texas House and is pending in the Senate.
The outcry prompted the hog bait’s manufacturer, Scimetrics, to withdraw its Texas registration on Tuesday. The company says it can’t afford to fight the legal battles that seem likely, but opponents say the move is designed merely to table the bill requiring more research. Since the State Legislature meets every other year, once the body adjourns on May 29, the company could theoretically reregister. And now that the restraining order has expired, it could simply put the product back on the market.
Wild pigs provide hunters with a food source and a significant revenue stream, as slaughterhouses will pay $30 to $180 per pig. The slaughterhouses sell the cheaper cuts to pet food companies and the better ones to high-end restaurants. But it’s unlikely chefs will buy poisoned pork belly, bacon and short ribs, even if they are organic and free range.
“If Kaput or any warfarin hog bait is allowed, I cannot guarantee the meat I sell doesn’t have the drug in it,” said Will Herring, a hog hunter in Hubbard, Tex., near Waco, who last year founded Wild Boar Meats, which buys feral pigs and sells the meat to pet food companies. “It will kill my business,” which he said processes about 5,000 pigs a month. Also a lawyer, Herring filed the lawsuit that prompted the restraining order, supported by the Texas Hog Hunters Association and the Environmental Defense Fund.
Both hunters and environmentalists worry about collateral damage. The warfarin-laced bait is dispensed by a contraption that works a bit like a giant Pez dispenser; only a determined pig should be able to trigger the release. But video of a black bear ripping into the device recently caused Louisiana officials to halt plans to follow Texas’ lead in allowing use of the Kaput product. Moreover, pigs are messy eaters and inevitably litter the bait around, where other wildlife and pets can get it. And of course, there is the danger to humans, who may consume pork from a pig who ate the bait.
How can a common drug also be a poison? In fact, even when administered therapeutically, warfarin, which is widely prescribed to reduce the risk of blood clots and subsequent stroke, is the leading cause of adverse drug reactions requiring hospitalization among older Americans.
“Warfarin can be tricky to prescribe,” said Dr. Greg Marcus, director of clinical research in cardiology at the University of San Francisco School of Medicine. The drug works, he said, by inhibiting vitamin K synthesis, which in turn inhibits the production of proteins in the blood that control bleeding. Genetics, diet and even bacteria in the gut can affect how people respond to the drug. Some people can take 2 milligrams and hemorrhage, while others can take 10 milligrams to little effect. And one person’s safe dose one day can become a toxic dose the next.
“You have to do a lot of blood testing to monitor and fine tune the dose,” Marcus said.
Before relinquishing the registration last week, Richard Poché, the president of Scimetrics, said a lethal dose for pigs is 3 milligrams per kilogram of body weight. Since the bait contains 0.005 percent warfarin, he said, pigs would have to eat about 2.7 kilograms, or about 6 pounds, to die.
But judging from the experience of wildlife officials who experimented with warfarin to poison feral hogs in Australia in the 1980s, it seems pigs are a lot like humans, in that the toxic dose is hard to peg.
According to Jim Hone, an emeritus professor of wildlife management at the University of Canberra in Australia who participated in that research, animal welfare concerns led them to stop using warfarin. “It took on average seven to 10 days for the animals to die,” suffering all the while from internal bleeding, he said. “It didn’t seem humane.” He also said there is not enough evidence to discount the risk posed to wildlife such as deer and birds that may eat the poison or predators and scavenger species such as mountain lions and buzzards that might eat the poisoned pigs.
Warfarin is still used in Australia as a rat poison, just as it is in the United States, though it has become less popular because rats seem to develop a tolerance for it (which pharmacologists said would most likely be the case for pigs). It was approved in the United States first as a rat poison in 1952 and as an anticoagulant for humans two years later. Warfarin was initially discovered in the 1920s after cattle started dying from internal bleeding, and the cause was traced to moldy clover silage. The responsible compound was later identified and synthesized to make the drug.
People who take warfarin have increasingly begun to question whether it’s wise, given that small doses can kill 300-pound feral hogs. But doctors still urge its use to reduce the risk of stroke. Marcus said for those with atrial fibrillation, a kind of irregular heartbeat, closely monitored warfarin dosing reduces the risk of stroke from about 5 percent to 1 percent a year. There are newer anticoagulants on the market, but they, too, have worrisome side effects. The newer drugs are also often not covered by insurance because they are so much more expensive than warfarin.
For his part, Commissioner Miller, a former rodeo champion who advised the Trump campaign on agriculture, has framed the withdrawal of the Kaput product as a disconnect between rural and urban Texas. “The hard-working folks who turn the dirt and work from sunup to sundown have fallen victim to lawyers, environmental radicals and the misinformed,” he said in a statement. “Once again, politically correct urban media hacks and naysayers win out against the rural folks who produce the food and fiber everyone needs.” Kate Murphy is a journalist who writes frequently for The New York Times.