Merck Animal Health, known as MSD Animal Health outside the United States and Canada, is the global animal health business unit of Merck, announced the results of a head-to-head research study that showed Activyl (indoxacarb) was more effective than Frontline Plus (fipronil [s]-methoprene) in controlling flea populations on pets. Activyl eliminated more than 99 per cent of fleas on pets after two monthly applications versus a 54.8 per cent reduction achieved by Frontline Plus (p= 0.0079).1 At the end of the two-month study, nearly five times more pets treated with Activyl were flea free, and Activyl users found significantly fewer fleas in their homes.1

“The pets in this study had the largest natural flea burdens the investigators had ever seen and were under continual reinfestation pressure. The data clearly show that Activyl was still able to effectively control the flea infestations,” said Kathleen Heaney, D.V.M., director of technical services for Merck Animal Health. “Following monthly treatments, pets treated with Activyl saw a reduction in fleas of 95 per cent at one month and 99.1 per cent at two months. In contrast, pets treated monthly with Frontline Plus saw a reduction of 49.5 per cent at one month and a reduction of 54.8 percent at two months.”

Flea control is critical to maintaining good pet health, as fleas can cause anaemia and allergic dermatitis, and can also transmit bacteria and other parasites to dogs and cats. The success or failure of products for flea control depend on a product’s ability to suppress flea reproduction for the duration of the treatment period. A single female flea can lay up to 50 eggs per day.

“When used as directed, Activyl has been shown to kill fleas before they lay eggs for a full month and beyond, which means the product more effectively controlled flea reproduction, and as a result, there were significantly fewer fleas in homes where pets were treated with Activyl,” said Dr. Heaney. “This also meant a reduction in emerging flea populations. We are excited about the findings from this study, and it reinforces our confidence in the performance of Activyl.”

Thirty-two dogs and three cats with natural flea infestations living in 18 homes were treated topically with a 19.53% w/w spot-on formulation of indoxacarb. Another 30 dogs and two cats living in 19 different homes were treated topically with either fipronil (9.8% w/w)/(s)-methoprene (8.89% w/w) or fipronil (9.8% w/w)/(s)-methoprene (11.8% w/w), respectively. Homes were randomly assigned to treatment. All products were applied according to label directions by study investigators on day 0 and again between days 28 and 30. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, 28–30, 40–45, and 54–60.

The research study, which took place last summer in Tampa, Fla., was conducted by Michael Dryden,  Kansas State University, to evaluate and compare two spot-on topical flea products to control flea infestations on naturally infested dogs and cats: Activyl by Merck Animal Health and Frontline Plus by Merial.