FDA Grants Merck Animal Health Emergency Use Authorization (EUA) for BRAVECTO (fluralaner) Chews for the Treatment of New World Screwworm Infestations in Dogs and Puppies

EUA for BRAVECTO Chews provides veterinarians with an important new tool as the United States responds to the growing threat of New World screwworm

RAHWAY, N.J., November 3, 2026 - Merck Animal Health, known as MSD Animal Health outside of the United States and Canada, a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK), today announced that the U.S. Food and Drug Administration (FDA) has granted Emergency Use Authorization (EUA) for BRAVECTO Chews for the treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis) in dogs and puppies.

The EUA comes as veterinarians, animal health officials and producers continue efforts to prepare for and respond to the emerging New World screwworm threat in the United States. The authorization builds on Merck Animal Health's ongoing work evaluating the broad parasiticidal activity of fluralaner across multiple species and adds an important canine option to the company's growing portfolio of solutions supporting New World screwworm preparedness.

"New World screwworm poses a serious risk to animal health and welfare, and the need for effective treatment options has never been greater," said Meg Conlon, DVM, executive director of U.S. Companion Animal Veterinary Services, Merck Animal Health. "We worked closely with regulatory authorities to ensure veterinarians have access to additional tools when they need them most. This EUA reflects both the strength of the science supporting BRAVECTO and our commitment to helping protect companion animals during times of heightened disease risk."

The FDA's decision was supported by the totality of available scientific evidence, including data from an effectiveness study, which provides a reasonable expectation that BRAVECTO Chews may be effective for the treatment of New World screwworm (Cochliomyia hominivorax) myiasis in dogs and puppies. In that study, dogs receiving a single oral dose of BRAVECTO achieved complete elimination of live larvae from the lesions within 24 hours following treatment, with no treatment-related safety concerns observed¹.

"Rapid intervention is critical when managing New World screwworm infestations," said Frank Guerino, Ph.D., associate vice president of global pharmaceutical development, Merck Animal Health. "The available data support a reasonable expectation that BRAVECTO Chews can quickly eliminate larvae in affected dogs. Combined with the product's established duration of flea and tick protection for up to 12 weeks^*, this authorization provides veterinarians with an important new option as they respond to an evolving animal health threat."

For additional information on the EUA, please refer to the BRAVECTO Chews EUA Fact Sheet.

Supporting Veterinary Preparedness
Merck Animal Health has been actively engaged in preparedness efforts surrounding New World screwworm, collaborating with veterinarians, industry organizations and regulatory authorities to help address the evolving threat. The company has also supported scientific education and information-sharing initiatives focused on detection, prevention and response strategies. BRAVECTO Chews with EUA-specific labeling are expected to become available to veterinarians by early second quarter of 2027.

This EUA further expands Merck Animal Health's commitment to helping address New World screwworm across species. In 2025, the FDA granted conditional approval for EXZOLT^™ CATTLE-CA1 (fluralaner topical solution) for the prevention and treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis) and treatment and control of cattle fever tick (Rhipicephalus microplus) in beef cattle 2 months of age and older and replacement dairy heifers less than 20 months of age.

About New World Screwworm
New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae infest living tissue, causing a condition known as myiasis. Infestations can lead to severe tissue damage, secondary infections and, if left untreated, significant morbidity and mortality in affected animals.

Key Information
- BRAVECTO has not been approved for the treatment of NWS myiasis in dogs and puppies;
- BRAVECTO has been authorized by FDA under an EUA for the treatment of NWS myiasis in dogs and puppies;
- BRAVECTO is authorized as described herein only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of BRAVECTO under Section 564(b)(1) of the FD&C Act, 21 U.S.C. § 360bbb-3(b)(1), unless the declaration is terminated or the authorization is revised or revoked sooner.
- FDA has granted EUA for BRAVECTO Chews for Dogs for the treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis) in dogs and puppies.
- For New World screwworm, the authorization was supported by data from a field study evaluating BRAVECTO Chews in dogs naturally infested with New World screwworm larvae. In the study, no live larvae were detected in the lesions at 24 hours after treatment with a single oral dose of BRAVECTO Chews¹.
- New World screwworm is a parasitic fly whose larvae infest living tissue and can cause severe myiasis in animals.
- This authorization provides veterinarians with an additional option to help address New World screwworm infestations in dogs during the authorized emergency period.
- BRAVECTO Chews for Dogs provides flea and tick protection for up to 12 weeks^* and is available through licensed veterinarians.

About BRAVECTO^®
Since its introduction in 2014, BRAVECTO has provided longer-lasting flea and tick protection, with more than 450 million doses distributed in 100 countries over a decade. BRAVECTO is available in a variety of formulations, including products for both dogs and cats.

The flea lifecycle can last as long as 12 weeks, and monthly treatments may leave gaps in protection. Providing pets with continuous flea and tick protection is essential - whether the pet goes outside or not. Contrary to popular belief among pet owners, fleas and ticks are not only active in the spring and summer months and are a year-round risk. Fleas and ticks can easily latch onto dogs and cats and can spread serious diseases. Fleas are the most common external parasite found on pets. BRAVECTO products are available through licensed veterinarians. For more information, visit us.bravecto.com.

*BRAVECTO (fluralaner) Chews for Dogs kills fleas, prevents flea infestations, and kills ticks (black-legged tick, American dog tick, brown dog tick, and Asian longhorned tick) for 12 weeks. BRAVECTO Chews also kills lone star ticks for 8 weeks.

Important Safety Information
BRAVECTO^® (fluralaner) Chews for Dogs: The most commonly reported adverse reactions include vomiting, lethargy, diarrhea, anorexia and pruritus. In some cases, adverse events have been reported following use in breeding females. BRAVECTO Chews has not been shown to be effective for 12-weeks' duration in puppies less than 6 months of age. BRAVECTO Chews is not effective against lone star ticks beyond 8 weeks of dosing. Fluralaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia and seizures. Seizures have been reported in dogs receiving isoxazoline class drugs, even in dogs without a history of seizures. Use with caution in dogs with a history of seizures or neurologic disorders. Indicated for dogs 6 months of age and older. For complete safety information, refer to the Product Label.

About EXZOLT™
Important Safety Information
EXZOLT™ CATTLE-CA1 (fluralaner topical solution): Not for use in humans. Keep out of reach of children. Accidental exposure may cause skin and eye irritation. Highly flammable. Keep away from heat, sparks, open flame or other sources of ignition. Use only for the prevention and treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae (myiasis) and treatment and control of cattle fever tick (Rhipicephalus microplus) in beef cattle 2 months of age and older and replacement dairy heifers less than 20 months of age. Off-label use is strictly prohibited. Not for use in bulls intended for breeding 1 year of age and older, dairy calves, and veal calves. Cattle must not be slaughtered for human consumption within 98 days of treatment. For complete safety information and product dosing instructions, refer to the Product Label.

About Merck Animal Health

Merck Animal Health, a division of Merck & Co., Inc., Rahway, N.J., USA, is a global animal health business committed to The Science of Healthier Animals™. For more than 130 years, we have pioneered groundbreaking science. Today, we are driven by continuous innovation to develop breakthrough medicines, vaccines and technology. Rooted in direct experience on the farm and in the clinic, we work hand in hand with our customers every step of the way. Our singular focus is to empower those who care for animals, helping them manage their vital responsibility with confidence. Because when it comes to animal health, no one sees it like we do. For more information, visit www.merck-animal-health.com and connect with us on LinkedIn, Facebook, X (formerly Twitter) and Instagram.

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