New Report: Popular Cattle Drug Is Causing Animals' Hooves to Fall Off

An investigation into a popular growth promoter has revealed a shockingly cruel side effect.

December 31, 2013


It might sound like something out of a bad sci-fi flick, but the sad reality is that Zilmax, one of the most popular drugs given to cattle in the U.S., is suspected of causing cattle's hooves to fall off and leading to a spike in euthanized animals since its introduction.


The news agency Reuters conducted an in-depth investigation into the popular drug, which Merck introduced in 2007 and is credited with adding 33 pounds to the average 1,300-pound steer. The drug works so well, the agency found from USDA statistics, that ranchers harvested about 26 billion pounds of beef from 91 million cattle slaughtered in 2012—a pretty high efficiency compared to the 24 billion pounds of beef harvested from 135 million cattle in 1975.

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But that profit is coming at a cost to animal health. The Food and Drug Administration requires pharmaceutical companies to report adverse events related to their drugs—both human and animal—and a review of these events by Reuters revealed a spike in euthanasias after ranchers turned to Zilmax, some of which can be attributed to animals having to be "destroyed" after their hooves fell off. That's an exceedingly painful condition that animal welfare expert Temple Grandin likened to having your toenails ripped off.

"In the two years after Zilmax was introduced, the number of beef steers and heifers euthanized prior to slaughter at U.S. packing plants rose nearly 175 percent from previous levels," the news agency found. "The number of euthanized steers and heifers has ranged between 1,600 and 2,300 cattle each year since then. That new plateau is well above the average of 670 a year in the four years before Zilmax came on the market in 2007."

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And businesses are getting wary of the drug. After 17 Zilmax-treated cattle had to be destroyed after losing hooves on a trip to a Tyson slaughterhouse in Washington state, the agrigiant told ranchers it would no longer accept Zilmax-treated cattle. Cargill, another huge meatpacker, has also stopped taking animals treated with the drug.

Yet Merck continues to push the drug. Sales were briefly suspended after Tyson's 17 cattle deaths, which Merck wanted to investigate, but the company is trying to reinstitute sales by convincing veterinarians and ranchers that the drug can be safe if used properly.

If ever there was a reason to stick with organic, locally raised beef, this could be it. Growth promoters like Zilmax are banned in organic animal husbandry—which means your steak came from an animal that didn't suffer the cruelty of losing its hooves.

Read the full investigation: Special Report: Lost hooves, dead cattle before Merck halted Zilmax sales, Reuters, Dec. 31, 2013.