Newly Published Research Demonstrates the Fast Initial and Residual Speed of Kill of BRAVECTO® (fluralaner) Chews for Dogs AgainstBlack-Legged Ticks (Ixodes scapularis)

Study published in Parasites & Vectors demonstrates BRAVECTO® Chews for Dogs has rapid and persistent activity against newly acquired ticks.

RAHWAY, N.J., January 10, 2024 – Merck Animal Health, known as MSD Animal Health outside the United States and Canada, a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE:MRK), today announced the publication of a recent study demonstrating BRAVECTO® Chews for Dogs had faster residual speed of kill compared to Simparica TRIO® against the black-legged tick (Ixodes scapularis). All dogs administered BRAVECTO Chews were 100 percent tick-free at every 24-hour tick count. At no point were all dogs in the Simparica TRIO group free from ticks.

The study, “Comparison of the initial and residual speed of Ixodes scapularis kill on dogs treated with a single dose of BRAVECTO Chew (25 mg/kg fluralaner) or Simparica TRIO (1.2 mg/kg sarolaner, 24 µg/kg moxidectin, 5 mg/kg pyrantel)” is available at Parasites & Vectors.

“It’s important to kill ticks as quickly as possible because the longer a tick is able to feed uninterrupted, the greater the risk will be of a dog becoming infected with a tick-borne pathogen,” said Dr. Dorothy Normile, veterinary insights and medical affairs for Merck Animal Health. “This data, published by Kansas State University, allows veterinarians to make informed decisions when recommending tick control practices. In addition, it helps pet owners understand the importance of choosing a product that provides excellent and rapid activity against newly acquired ticks.”

The black-legged tick (Ixodes scapularis) has greatly expanded its range in North America and is now causing significant concern among veterinarians and pet owners. The quicker a newly acquired tick can be killed, the less time it has to transmit a potential illness to a dog, making a product’s residual-speed of tick kill extremely important for pets and pet owners alike. Per label, BRAVECTO Chews for Dogs effectively treats dogs infested with the black-legged tick for up to 12 weeks after administration of a single dose.

The researchers at Kansas State University, who were sponsored by Merck Animal Health, revealed the differences in Ixodes scapularis kill between BRAVECTO Chew and Simparica TRIO. At every time point evaluated, including initially and 28 days after administration, a higher proportion of the dogs treated with BRAVECTO Chew were tick-free when assessed 12 hours after a tick infestation. At each 24-hour tick count, all dogs in the BRAVECTO Chews group were tick-free. The results also showed that there was no point in the study where all dogs in the Simparica TRIO group were tick-free.

The black-legged tick remains a significant pest of pets and its range continues to expand in North America, so it is important that veterinarians and pet owners be aware of this tick’s pathogenic abilities as well as the most effective ways to manage infestations on dogs. To learn more about BRAVECTO and the products’ innovative flea and tick treatment abilities, visit


            Since its introduction in 2014, BRAVECTO has provided longer-lasting flea and tick protection, with more than 300 million doses distributed in more than 100 countries. BRAVECTO is available in a variety of formulations, including products for both dogs and cats.

The flea and tick life cycles can also last for months and missed doses of 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 parents, fleas and ticks are not only active in the spring and summer months, but they are a year-round risk.

Fleas and ticks can easily infest dogs and cats. They also can bite and pose health risks to human family members whether at home or outdoors. Ticks can spread serious diseases including rickettsiosis, anaplasmosis and borreliosis (Lyme disease), while fleas are the most common external parasite found on pets and can transmit bartonellosis (Cat Scratch disease) and tapeworms.

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.

About Merck Animal Health  

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than a century, we’ve been at the forefront of research, bringing forward medicines, vaccines and innovative health solutions for the world’s most challenging diseases. Merck Animal Health, a division of Merck & Co., Inc., Rahway, N.J., USA, is the global animal health business unit of Merck. Through its commitment to The Science of Healthier Animals®, Merck 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 connected technology that includes identification, traceability and monitoring products. Merck 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. Merck Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit and connect with us on LinkedIn, Facebook, X (Formerly Twitter) and Instagram.

Media Contact:

Laurel Mundth

+1 (908) 872-9783