FDA approves new poultry treatment to combat northern fowl mites

USA – The US Food and Drug Administration (FDA) has approved a new poultry treatment designed to tackle northern fowl mites, a common and costly parasite that affects chickens and other poultry. 

The product, EXZOLT, developed by Merck Animal Health, was tested at Pennsylvania State University and found to reduce mite populations by more than 90%.

The FDA approval, announced in July 2025, marks a breakthrough for poultry producers who have long struggled with mite infestations. 

Northern fowl mites feed on blood, leading to health problems, stress, and decreased egg production. Unlike conventional treatments, which are applied topically, EXZOLT is administered through drinking water and works systemically throughout the bird’s body.

A novel approach

Erika Machtinger, Associate Professor of Entomology at Penn State and one of the lead researchers on the project, explained why EXZOLT stands out.

“Current treatments are all topical, and additionally, mites have developed resistance to many of their active chemicals,” she said. “This new treatment is a veterinary-prescribed drug that works systemically, so it gets to all parts of the bird. Think of it like those flea and tick chewable tablets people give their dogs; it’s the same concept.”

While Merck Animal Health created the product, the path to FDA approval required extensive testing. Penn State’s College of Agricultural Sciences led the trials, with a team that included Machtinger, John Boney, Assistant Professor of Poultry Science, and Scott Kephart, Manager of the Poultry Education and Research Center.

Rigorous testing

The studies involved raising more than 1,000 broiler breeder and layer chicks, infesting them with northern fowl mites, and then treating them with EXZOLT. 

Birds in the treatment group received two doses, seven days apart, while control groups were given only water. Researchers closely monitored mite populations, bird weight, and health conditions over 28 days.

Kephart described the effort as particularly demanding. “A project of this size was a huge undertaking, especially with other projects taking up some of the available space. However, my team was determined and worked together to troubleshoot and make the project a success.”

The results were conclusive: treated birds had mite populations reduced by more than 90% compared to the control groups. The data then underwent a thorough review before being submitted to the FDA.

Industry impact

For Penn State, the project highlights the value of collaboration between academia and industry. Troy Ott, Dean of the College of Agricultural Sciences, said the approval is an example of science delivering practical solutions.

“This work is just another example of how Penn State uses science to solve problems in Pennsylvania and beyond,” Ott remarked. 

Ott added that the poultry industry is an economic driver of the Pennsylvania economy, and our scientists, working closely with industry stakeholders, focus on delivering science-based solutions to the challenges they face.

Machtinger emphasised the broader benefits of such partnerships. “For the college, these collaborations bring in funding, give our students hands-on experience, and strengthen our reputation as a place where industry knows they can come to solve tough problems,” she said.

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