Animal Health Professionals Site

5 September 2017

MSD Animal Health Launches First Systemic Treatment for Poultry Red Mites; EXZOLT® Virtually Eliminates Infestations in European Poultry Houses
Novel Approach Improves Poultry Welfare by Reducing Stress on Chickens

Milton Keynes, UK, September 5, 2017 – MSD Animal Health (a division of Merck & Co., Inc., Kenilworth, NJ, USA.) today announced the launch of EXZOLT® (fluralaner), the first systemic treatment for poultry red mite infestations – a novel approach that virtually eliminates poultry red mites in production houses of any size or type, including free range. Conveniently administered via drinking water, EXZOLT also improves poultry welfare by reducing stress associated with other forms of treatment, and minimises the exposure of workers and birds to chemical sprays.

“Poultry red mites are among the most threatening pests in the UK, contributing to increased stress levels, decreased weight gain and diminished egg quality and production in infested birds,” says Wesley Thorne, MSD Animal Health. “It is important to effectively treat poultry red mites as infestations not only affect the birds’ welfare, but also result in significant economic losses for poultry 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.i The total annual cost of poultry red mite infestations in the European egg laying industry is estimated to be €360 million, with more than 430 million hens in all production types – pullets, breeders and layer hens – suffering from infestations.

Poultry red mites are nocturnal feeders that hide during the day under manure, on perches and in cracks and crevices in the chicken house, where they lay eggs, making them difficult to eliminate. Previously available treatment options are labour-intensive and/or have achieved limited success in eliminating or controlling infestations. Mite infestations affect poultry workers as well, causing gamasoidosis, a skin condition characterized by rash and itching.

The safety of EXZOLT has been established through comprehensive clinical research studies. These studies demonstrated that EXZOLT virtually eliminates poultry red mites in production houses, and has an excellent safety profile for the birds and for human handling. No significant adverse events were reported.

“With a zero day withdrawal period, eggs from chickens treated with EXZOLT are safe to consume, making EXZOLT ideal for maintaining the health, performance and welfare of flocks while continuing to meet market demands and avoiding economic loss for producers,” adds Wesley Thorne, MSD Animal Health.


EXZOLT®, a first-of-its-kind product based on the fluralaner molecule for the treatment of poultry red mite infestations, works on the parasites’ nervous system and kills mites that have taken a blood meal, while having no reported impact for the host animal. Chickens are treated during an infestation. This ensures that both adult mites and nymphs are killed.

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 regime (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. EXZOLT starts working in mites within four hours after mites start to feed on treated chickens resulting in effective elimination of the mites.

i Mites of poultry. MSD Veterinary Manual. Click here to retrieve.