Elanco Secures First FDA Conditional Approval for a Dog Treatment Before the Screwworm Fly Even Arrives
As concerns about New World screwworm inch closer to home, Elanco Animal Health has made a move that many veterinarians will see as proactive rather than reactive. The company announced that Credelio QuattroTM-CA1 has received FDA conditional approval for the treatment of infestations caused by New World screwworm larvae in dogs. This marks the first time a companion animal product has earned conditional approval specifically for this parasite.
For veterinary professionals who have been following the screwworm situation with cautious interest, this approval matters. While the fly has not yet been detected in the United States, USDA reports confirm cases within a few hundred miles of the U.S.-Mexico border, all associated with cattle movement. Detection has reached as close as 70 miles south of the border. That proximity has pushed preparedness from theoretical to practical.
Credelio Quattro-CA1 contains lotilaner, moxidectin, praziquantel, and pyrantel in a chewable tablet. With this approval, it becomes Elanco’s third treatment option aimed at New World screwworm in companion animals, joining Credelio for dogs and Credelio CAT for cats, both of which previously received FDA Emergency Use Authorization. From a clinical standpoint, Credelio Quattro and Credelio Quattro-CA1 stand out for their broad parasite coverage. In addition to New World screwworm, the product line covers ticks, fleas, heartworm disease, roundworms, hookworms, and tapeworms. For busy practices and shelters, that kind of all in one coverage aligns well with modern expectations for simplicity and compliance.
The conditional approval was supported by published research evaluating lotilaner against Cochliomyia hominivorax larvae. In a peer reviewed study in Parasites and Vectors, naturally infested dogs treated orally at the minimum recommended dose achieved 100 percent efficacy within 24 hours. For veterinarians, that rapid response is especially relevant given the aggressive and tissue destructive nature of screwworm myiasis. According to FDA standards, conditional approval means the product has been shown to be safe and has a reasonable expectation of effectiveness. This pathway is often used to address urgent or emerging animal health threats while additional data are collected. In this case, it allows veterinarians to have a tool ready before an outbreak reaches companion animals in the U.S.
Elanco has emphasized that this approval is about readiness. The goal is to ensure veterinarians, shelters, and pet owners are not caught off guard if New World screwworm crosses the border. Updated product labeling reflecting the conditions of use for both Credelio Quattro and Credelio Quattro-CA1 is expected to roll out in 2026, with both products appearing on the same packaging. For millennial veterinarians balancing evidence based medicine with real world logistics, this development signals a shift toward prevention planning rather than crisis response. Even without confirmed U.S. cases in dogs, having FDA conditionally approved options in place may offer peace of mind and a clearer action plan should the situation change.
