Merck & Co., Inc. (MRK) Stock: Gains FDA Nod for New Cattle Antiparasitic

TLDR

• Merck receives conditional FDA approval for Exzolt Cattle-CA1 and Dectomax-CA1.
• Treatments target New World screwworm and cattle fever ticks, key threats to U.S. livestock.
• Stock trades at $101.53, down 0.72% as investors react to regulatory updates.
• FDA fast-tracked approval to address urgent animal health needs in the agriculture sector.
• MRK underperforms the S&P 500 across all major trailing return periods.

Merck & Co., Inc. (MRK) traded at $101.53, down 0.72%, after securing conditional approval from the U.S. Food and Drug Administration for two new cattle antiparasitic solutions.

Merck & Co., Inc., MRK

The treatments aim to protect the U.S. cattle population from New World screwworm larvae and fever ticks, two threats that pose serious economic risks to U.S. agriculture. While this marks a significant regulatory milestone for Merck Animal Health, investors showed muted reaction, with the stock lagging broader market benchmarks.

New FDA Approvals Target Livestock Threats

Merck announced that its animal health division received conditional approval for Exzolt Cattle-CA1, a pour-on solution designed to combat New World screwworm larvae. According to Merck Animal Health President Rick DeLuca, these larvae represent a growing danger that could generate “hundreds of millions” in economic losses for cattle producers.

The FDA also granted conditional approval to Dectomax-CA1 (doramectin injection) for treatment and prevention of New World screwworm infestations, with a reinfestation prevention window of 21 days. The approval is significant as it marks the first conditional authorization for New World screwworm treatment in the U.S.

The FDA emphasized the urgency of providing cattle producers with immediate solutions. Commissioner Marty Makary stated that the fast-tracked decision supports farmers facing rising parasite threats. Since comprehensive effectiveness studies would require complex research, conditional approval allows the drug to reach the market while additional data is collected.

Product Background and Regulatory Details

Dectomax-CA1 leverages the same active ingredient and dosage as the already fully approved Dectomax product used to treat nematode and arthropod parasites in cattle and swine. Due to this existing safety data, the FDA did not require new safety or manufacturing submissions for the updated formulation.

The withdrawal period for treated cattle is 35 days, identical to the original Dectomax product. The treatment is not approved for female dairy cattle over 20 months or for preruminating calves. Bottles will be available in 250 mL and 500 mL formats, and labeling will include indications for both Dectomax and Dectomax-CA1.

Producers and veterinarians are encouraged to use antiparasitic drugs only when medically necessary to preserve long-term drug effectiveness and prevent resistance.

Market Performance and Competitive Standing

Merck’s stock underperformed major benchmarks across all trailing periods. As of December 4, 2025, Merck delivered a 5% YTD return, far behind the S&P 500’s 16.57%. The company’s one-year return sits at 3.87%, also below the index’s 12.64% gain. Long-term performance shows similar trends, with Merck posting only 0.91% over three years compared to the S&P 500’s 68.38%.

Despite weak stock momentum, Merck remains a leading player in human and animal health, with its animal health division contributing meaningfully to revenue and long-term product innovation.

Agricultural and Economic Impact

The conditional approvals come at a critical time for U.S. agriculture. Rising New World screwworm cases increase the threat of widespread livestock losses. With potential economic damages reaching hundreds of millions, access to effective antiparasitic treatments is vital.

Merck’s new products are expected to support cattle producers beginning in the first quarter, providing timely protection during peak parasite activity periods. As the FDA continues reviewing additional antiparasitic treatments, Merck stands at the forefront of developing solutions for livestock health threats.

The post Merck & Co., Inc. (MRK) Stock: Gains FDA Nod for New Cattle Antiparasitic appeared first on CoinCentral.