FDA reviewing reports of illness and deaths involving feedlot cattle drug Experior

A new investigation by Investigate Midwest found that the U.S. Food and Drug Administration had received 75 adverse event reports involving lubabegron, the active ingredient in the cattle feed drug Experior, as of July 2026. Fifty-nine reports included deaths. Others described lameness or difficulty standing. The FDA told the newsroom it was evaluating the reports, which do not establish that the drug caused the problems.

The investigation, published November 9, examined both reports from feedlots and studies submitted before approval. In two of those studies, researchers recorded bloat in cattle given Experior and none in the comparison groups. Bloat occurs when gas builds up in a cow’s digestive system and can become life-threatening. The FDA told Investigate Midwest that there were too few cases to make a meaningful statistical comparison. Elanco, the manufacturer, told the newsroom it stood by the drug’s safety and effectiveness.

The FDA approved Experior in 2018 for beef steers and heifers kept in confinement for slaughter. The approval covers use during the final 14 to 91 days of feeding to reduce ammonia emissions relative to the animals’ live weight and carcass weight. The product label says researchers measured emissions from individual animals or small groups under controlled conditions. Those results cannot reliably predict how much ammonia would be reduced across a whole herd or farm.

Why This Matters for Animals

Difficulty walking or standing is a serious welfare concern for cattle. The FDA uses adverse event reports to flag potential problems that may need closer study after a drug goes on sale. The reports can show what happened to animals in individual cases, but they do not show how often the same problems occur across all cattle receiving the drug.

The investigation brings together two kinds of evidence: observations made in controlled studies before approval and reports from feedlots afterward. To determine whether the drug increases the risk of harm, researchers would need to compare outcomes in cattle fed Experior with outcomes in similar cattle that did not receive it, while accounting for other factors such as feed, pen conditions and other treatments.

Source: Investigate Midwest