Treating Poultry Mite with EXZOLT® (fluralaner) Significantly Reduces Mite-Related Stress and Improves Poultry Well-Being

Data of First European Study Investigating the Effect of EXZOLT® on Stress-Parameters in Chickens under Field Conditions Presented at World Veterinary Poultry Association Congress.

MADISON, N.J., September 19, 2019 – MSD Animal Health, a division of Merck & Co., Inc., Kenilworth, N.J., USA, today announced data from the first study under field conditions on stress-parameters in poultry, presented at the 21st World Veterinary Poultry Association Congress (WVPAC 2019), September 16-20, in Bangkok, Thailand. It shows that treating poultry red mite with EXZOLT® (fluralaner) improved poultry well-being and lowered red mite infestation-related stress.

EXZOLT® is the first systemic treatment for poultry red mite infestations. Conveniently administered via drinking water, it employs a novel approach that virtually eliminates poultry red mites in production houses of any size or type, including free-range.

The study was conducted on selected farms in Spain, Germany and France to evaluate the effect of EXZOLT® on red mite infestation-related stress in laying hens in different housing systems. Physiological, behavioral and health parameters of mite-related stress were measured before and after treatment with EXZOLT®.

The study found EXZOLT® reduced physiological parameters of stress, including levels of corticosterone in the blood, as well as behavioral parameters, including head, body and wing shaking, head-scratching, preening plumage, gentle and severe feather pecking, aggression, and activity during the day and night. Hens showed a return to normal or improvement of stress indicators and a reduced incidence of comb discoloration, an indicator of blood loss, within a few days after the first application of EXZOLT®. Results were consistent across different housing systems, breeds and ages.i

“Mite infestations significantly impact the welfare of chickens by inducing chronic stress and cause economic loss for poultry producers by diminishing egg quality and production,” said Rik Koopman, DVM, Global Technical Director, MSD Animal Health. “The physiological stress caused by poultry mite infestations, indicated by increased levels of the stress hormone corticosterone, has previously been studied only under lab conditions. We are pleased to share data from the first study of mite-related stress under field conditions that show the benefits of EXZOLT® for chickens and producers.”

Poultry red mites are a top-five cause of economic loss in European layer and breeder operations and in many other countries, as infestations cause significant stress to poultry, decrease reproductive potential in males, egg production in females and weight gain in young birds. The total annual cost of poultry red mite infestations in the European egg laying industry is estimated to be 360 million euros, with more than 430 million hens in all production types – pullets, breeders and layer hens – suffering from infestations.

About EXZOLT® (fluralaner)
EXZOLT®, a first-of-its-kind product based on the fluralaner molecule for the treatment of poultry red mite infestations and kills mites that have taken a blood meal, while remaining safe for the host animal. Chickens are treated during an infestation. This ensures that both adult mites and their nymphs are killed. EXZOLT® starts working in mites within four hours after mites start to feed on treated chickens, resulting in effective elimination of the mites.

Clinical data from three European dose-confirmation studies and an extensive nine-site field study showed EXZOLT® provided virtual elimination of poultry red mite populations in all treated layer, breeder and/or pullet houses. In these studies, the recommended EXZOLT® dosage regimen (0.5 mg/kg body weight twice at a seven-day interval) achieved 99 percent mite-killing efficacy for at least 15 days, which spans two mite life cycles.

Please see prescribing information for EXZOLT® at

About MSD Animal Health
For more than a century, MSD, a leading global biopharmaceutical company, has been inventing for life, bringing forward medicines and vaccines for many of the world’s most challenging diseases. MSD Animal Health, a division of Merck & Co., Inc., Kenilworth, N.J., USA, is the global animal health business unit of MSD. Through its commitment to the Science of Healthier Animals®, MSD Animal Health offers veterinarians, farmers, pet owners and governments one of the widest ranges of veterinary pharmaceuticals, vaccines and health management solutions and services as well as an extensive suite of digitally connected identification, traceability and monitoring products. MSD Animal Health is dedicated to preserving and improving the health, well-being and performance of animals and the people who care for them. It invests extensively in dynamic and comprehensive R&D resources and a modern, global supply chain. MSD Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit or connect with us on LinkedIn and Twitter.

iPresented at the MSD Animal Health WVPA Congress symposium, “Inventive Solutions for the Hatchery & Breakthrough New Treatment for Poultry Mites, Thursday, September 19, 2019 at the 21st World Veterinary Poultry Association Congress (WVPAC 2019), Bangkok, Thailand.