Oral Fluralaner Clears Screwworm Infestations in Dogs

A multicenter clinical study published in Parasites & Vectors reports that a single oral administration of fluralaner, the active ingredient in Bravecto chewable tablets, achieved 100% wound clearance in dogs naturally infested with New World screwworm (Cochliomyia hominivorax). The research, conducted in endemic regions of Brazil, evaluated the therapeutic efficacy of this systemic isoxazoline treatment against the dipteran fly, which causes extensive tissue damage and predisposes affected hosts to secondary infections in both humans and animals. The study aimed to determine if this oral alternative could effectively manage canine myiasis compared to traditional labor-intensive topical treatments.

The study included fifteen client-owned dogs presenting with natural New World screwworm infestations of varying severity. Each animal received fluralaner chewable tablets at the approved dose range of 25 to 56 milligrams per kilogram of body weight. Clinical evaluations were performed 24 hours after administration, during which researchers examined the wounds and collected all larvae, whether expelled or still present within the lesions.

The collected larvae were counted and classified according to their motility to assess the immediate impact of the treatment on the parasite population. Twenty-four hours post-treatment, no live larvae remained within any of the lesions, resulting in a 100% wound clearance rate. The overall total larvicidal efficacy was calculated at 94.36%, a figure that reflects the combined mortality of both intralesional parasites and those expelled from the host.

The larval expulsion rate was recorded at 13.99%, corresponding to 206 out of the total 1,472 larvae collected. Among these expelled parasites, 83 larvae, representing 5.63% of the total count, were expelled alive. To assess the long-term viability of the expelled parasites, the researchers transferred the 83 live third-instar larvae to pupation substrates.

These larvae were maintained under controlled laboratory conditions to monitor for adult emergence. The results showed that none of the live-expelled larvae developed into adult flies, resulting in a 0% emergence rate. This outcome indicates that exposure to fluralaner caused irreversible physiological damage to the parasites, preventing them from completing their life cycle even after being expelled from the host.

The safety profile of the treatment was monitored throughout the study period, and no adverse events were reported in any of the fifteen dogs following the administration of fluralaner. The study notes that traditional management of New World screwworm has historically relied on labor-intensive topical treatments. The complete interruption of the parasite’s life cycle in treated dogs suggests an epidemiological benefit beyond individual recovery.

By preventing the emergence of adult flies from treated hosts, the treatment reduces environmental contamination with screwworm larvae and pupae. The authors conclude that these findings support the potential integration of isoxazolines into public health and One Health strategies aimed at limiting the geographic expansion of New World screwworm outbreaks in Neotropical regions. The study’s design, focusing on naturally infested dogs in endemic regions, provides relevant data for veterinary practice in similar settings.

Subject of Research: Therapeutic efficacy of oral fluralaner against New World screwworm infestation in dogs

Article Title: Evaluation of the therapeutic efficacy of fluralaner chewable tablets (Bravecto®) against New World screwworm (Cochliomyia hominivorax) infestation in dogs

Article References: Monteiro, A. C. M. P., Bispo de Carvalho Teixeira, J., Bittar, T. V., Queiroz Neto, I. L., Cruz, R. J. C., Veloso, J. F., de Almeida Borges, F., de Paula, M. A. B., Arakaki, C. K., Sales, M. E. C., Lopes, G. E., da Nobrega, A. M., de Carvalho Mariano, C., Chiummo, R. M., Vettorato, L., da Silva, F. O., Guerino, F., Albuquerque, G. R., & Carlos, R. S. A. (2026). Evaluation of the therapeutic efficacy of fluralaner chewable tablets (Bravecto®) against New World screwworm (Cochliomyia hominivorax) infestation in dogs. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07757-8

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07757-8

Keywords: fluralaner, New World screwworm, Cochliomyia hominivorax, canine myiasis, isoxazolines, veterinary medicine, parasitic disease, One Health, therapeutic efficacy, Bravecto, Evaluation, therapeutic