“FDA Grants First Emergency Use Authorization for Elanco’s Credelio to Combat New World Screwworm Threat in Dogs”

Elanco Animal Health recently received the first-ever emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA) for its flea and tick drug Credelio (lotilaner) to treat dogs infected with the New World screwworm (NWS), a flesh-eating parasitic fly posing a growing threat near the U.S.-Mexico border. This authorization came on October 24, 2025, to address a potential emerging animal health crisis and protect U.S. animal populations.​

New World screwworm larvae consume living tissue, causing severe injury and even death in affected animals. Although eradicated in the U.S. several decades ago, recent confirmed cases of NWS infestations have been documented less than 70 miles south of the U.S.-Mexico border, raising concerns about a resurgence in the region. The parasite affects warm-blooded animals, including livestock, pets, and wildlife, threatening animal health and food security. While human infections are rare in the U.S., the parasite’s presence calls for urgent veterinary intervention.​

The FDA’s emergency use authorization enables veterinarians and pet owners to use Credelio as an immediate treatment option for NWS infestations in dogs. This is noteworthy as it marks the FDA’s first EUA for an animal drug targeting this parasitic threat. The authorization follows a declaration by the U.S. Department of Health and Human Services (HHS) in August 2025, which recognized a significant risk of a public health emergency related to NWS, enabling the FDA to issue EUAs for animal drugs under special conditions.​

Credelio has demonstrated strong efficacy against NWS larvae in dogs. A peer-reviewed study published in Parasites & Vectors reported that administering the drug at the recommended minimum dosage resulted in a 100% kill rate of NWS larvae within 24 hours in naturally infested dogs, underscoring its potential as an effective treatment. Dr. Ellen deAbander, Executive Vice President of Innovation and Regulatory Affairs at Elanco, emphasized the significance of the authorization: “This first-ever Emergency Use Authorization for NWS in canines offers reassurance to veterinarians and pet owners, knowing there is an approved treatment option ready for use when necessary”.​

The designation of emergency use allows for rapid deployment of the drug in a situation where no approved alternatives are available and a potential widespread outbreak could severely impact animal health and the livestock industry. Given the recent approach of NWS toward the U.S. border and associated risks, having an approved treatment distributed in advance supports a proactive public health approach rather than reactive crisis management.​

NWS infestation in animals causes myiasis—parasitic larvae feeding on host tissue—which can lead to severe wounds and systemic illness. Treatment delays can result in fatal consequences for infected animals. The development and emergency approval of Credelio brings immediate relief potential and assists in containment efforts to prevent the spread of this infestation into the U.S. mainstream animal populations.​

While this FDA action is a significant step forward, there are limitations to emergency use authorizations. EUAs are temporary measures designed for crisis response and do not replace the standard drug approval process. Credelio’s use for NWS treatment is currently limited to emergency situations, and further data collection and monitoring will continue to ensure safety and effectiveness in broader clinical practice.​

Veterinarians should exercise clinical judgment and maintain a valid veterinary-client-patient relationship when prescribing any treatment. Additionally, pet owners should consult with qualified animal health professionals before administering Credelio or any medication, and follow all FDA and veterinary guidance to optimize outcomes while minimizing risks.fda​

In summary, Elanco’s Credelio represents a critical advance in managing the looming threat of New World screwworm infestations in dogs near the U.S. border. The FDA’s emergency use authorization supports proactive containment efforts, providing veterinarians and pet owners with an evidence-based treatment option backed by peer-reviewed research. This initiative exemplifies coordinated public health responses involving FDA, HHS, USDA, and industry stakeholders to safeguard animal health and the food supply against reemerging parasites—highlighting the importance of preparedness in emerging veterinary threats.

Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.

References:

1. Reuters, “Elanco gets US FDA emergency nod for dog drug as threat of flesh-eating parasite looms,” October 24, 2025