INDIANAPOLIS, Ind., October 24, 2025 — In a landmark decision for veterinary medicine and regulatory preparedness, Elanco Animal Health Incorporated (NYSE: ELAN) has received the first-ever Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA) for Credelio™ (lotilaner) to treat New World screwworm (NWS) infestations in dogs. The authorization—issued even before detection of the fly in U.S. territories—marks a historic step in animal health emergency readiness, providing veterinarians and pet owners with a rapid-response treatment option for a potentially devastating parasitic threat.
Science Significance
The New World screwworm (Cochliomyia hominivorax) is one of the most destructive parasites known to veterinary medicine. Female flies lay eggs in the wounds of warm-blooded animals, and the hatched larvae feed on living tissue—causing severe pain, tissue necrosis, and, in untreated cases, death. While eradicated from the United States since the 1980s, recent confirmed cases in northern Mexico, within 70 miles of the U.S. border, have heightened vigilance across veterinary and agricultural sectors. Credelio (lotilaner)—already approved for flea and tick prevention—was shown in peer-reviewed research (Parasites & Vectors, 2023) to be 100% effective in eliminating NWS larvae within 24 hours in naturally infested dogs following a single oral dose. The mechanism of action involves rapid larval expulsion, supported by lotilaner’s neurotoxic effect on the parasite’s central nervous system. Although the initial study involved a limited cohort of 11 dogs in Brazil, the scientific data provide compelling early evidence of efficacy, validating Credelio’s potential as a first-line therapeutic in emergency conditions. “This first-ever EUA for NWS in dogs gives veterinarians and pet owners peace of mind, knowing an authorized treatment option is available as soon as it may be needed,” said Dr. Ellen de Brabander, Executive Vice President of Innovation and Regulatory Affairs at Elanco.
Regulatory Significance
The EUA—issued under Section 564(b)(1) of the Federal Food, Drug, and Cosmetic Act (FD&C Act)—represents the first authorization of its kind for a parasitic condition in companion animals. The FDA’s proactive move demonstrates an adaptive regulatory framework designed to anticipate, not merely react to, emerging animal health threats. By issuing the EUA prior to confirmed domestic cases, the agency underscores its commitment to preparedness and rapid deployment of therapeutic countermeasures against vector-borne and zoonotic diseases.
This milestone reinforces the importance of collaboration between the FDA, Elanco, and the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) to establish coordinated surveillance and response systems against invasive parasites.
Business Significance
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For Elanco, this authorization strengthens its leadership in veterinary innovation and parasite control while showcasing its regulatory agility and scientific credibility. The EUA aligns with the company’s broader strategy to extend existing product technologies into new therapeutic domains, particularly those relevant to biosecurity and One Health priorities. Elanco’s Credelio franchise, already a market leader in flea and tick protection, now stands as the first oral treatment officially recognized for use against NWS in emergency contexts. This proactive readiness enhances Elanco’s market differentiation and supports the company’s long-term growth in companion animal health, estimated at over $150 billion globally by 2030. Moreover, the EUA underscores Elanco’s capacity to mobilize rapid regulatory submissions based on emerging threats, a capability increasingly critical as climate shifts and global trade alter parasite migration patterns.
Patients’ Significance
For pet owners and veterinarians, this decision delivers more than regulatory news—it offers immediate peace of mind. The NWS fly lays up to 1,000 eggs during its 10–30-day lifespan, often on small wounds such as tick bites or scratches. Upon hatching, larvae feed aggressively on live tissue, resulting in rapid deterioration, secondary infections, and, in severe cases, death. “Any break in the skin—from a scratch to a surgical incision—can become an entry point for NWS due to its invasive nature,” explained Dr. Casey Locklear, Elanco parasiticide lead and Texas-based veterinarian. Preventive strategies—including year-round flea and tick control with Credelio—not only minimize scratching and wounds but also reduce potential breeding sites for the fly. In practical terms, the EUA ensures veterinarians across the U.S. are equipped with an evidence-based tool should the parasite re-emerge, potentially saving countless animals from severe suffering and loss of life.
Policy Significance
The FDA’s decision also reflects broader public policy alignment with the One Health initiative, which integrates animal, human, and environmental health efforts to prevent cross-species disease threats.
By authorizing Credelio preemptively, the FDA and USDA jointly emphasize the strategic importance of pre-approval preparedness in veterinary care. This authorization serves as a template for future emergency responses, allowing regulatory bodies to act swiftly when emerging pathogens threaten national animal health security.
The move also bolsters confidence in the U.S. veterinary supply chain, ensuring treatment access without delays tied to traditional post-detection approval timelines.
Transaction Highlights
Under the terms of the authorization, the FDA has granted Elanco’s Credelio (lotilaner) emergency-use status for treating infestations caused by Cochliomyia hominivorax larvae (New World screwworm) in dogs and puppies. The EUA remains active for the duration of the emergency declaration under the FD&C Act, or until revoked sooner. The decision follows Elanco’s submission of clinical efficacy data and peer-reviewed scientific literature supporting Credelio’s performance against naturally occurring NWS infestations. This milestone marks a historic first in veterinary emergency preparedness, reinforcing Elanco’s and the FDA’s shared mission to protect animal welfare through evidence-based innovation.
Source: Elanco Animal Health Press Release
