Clinical
Credelio Quattro-CA1 receives conditional approval from the FDA to treat New World Screwworm
Credelio Quattro-CA1 now has a new indication on its label in the fight to protect dogs from the threat of New World Screwworm.
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On Thursday, Dec. 18, Elanco announced that their product Credelio Quattro-CA1 (lotilaner, moxidectin, praziquantel, and pyrantel chewable tablets) received conditional approval from the FDA for the treatment of New World Screwworm (NWS) in dogs eight weeks of age and older.
This is the first such conditional approval to treat NWS, and it comes on the heels of the emergency use authorization (EUA) of Credelio (lotinaler) and Credelio CAT (lotilaner) to treat NWS.
Credelio Quattro and conditional approval
According to the press release, conditional approval was based on studies showing that lotilaner, one of the active ingredients in Credelio Quattro-CA1, demonstrated 100% efficacy against Cochliomyia hominivorax (NWS) larvae within 24 hours of treatment in dogs naturally infested with the parasite.
Credelio Quattro was originally approved by the FDA in October 2024 for protection against fleas, ticks, heartworms, roundworms, hookworms, and three species of tapeworms in dogs eight weeks of age and older.
According to the FDA, the conditionally approved product’s label “will contain both Credelio Quattro and Credelio Quattro-CA1 indications.”
EUA versus conditional approval
EUA is a temporary designation that allows either a drug that has been previously approved for other indications or an unapproved drug to be used to address a public health threat as determined by the Department of Health and Human Services (HHS) when the drug is show to have a “reasonable expectation of effectiveness” against the threat according to the FDA, and no “adequate, approved, and available alternative” exists. The EUA can be revoked by HHS once these conditions are no longer present.
Conditional approval, on the other hand, is meant to allow a drug to be marketed and used for a particular indication while an application for full approval is still pending. Full approval by the FDA requires the manufacturer to demonstrate that the drug is safe and has “substantial evidence of effectiveness.” This approval is valid for one year and can be renewed for up to four more years at the manufacturer’s request while they are gathering effectiveness data to present to the FDA.
The threat of NWS
HHS declared in August 2025 that there is “significant potential for a public health emergency” due to the advancement of NWS in Mexico toward the southern US border, with at least one known case detected less than 70 miles from the US-Mexico border, according to the USDA. According to the CDC, as of December 12, 2025, there have been 140,000 confirm cases of NWS in animals and more than 1,000 cases in people.
Casey Locklear, DVM, parasitology lead for Elanco, advised that should the parasite reach the US, pet owners can reduce their pets’ risk of infestation with NWS by monitoring them closely for any wounds or minor scratches that could serve as an entry point for the parasite.
“I also recommend pet owners keep their dogs on year-round parasite protection like Credelio Quattro to help minimize self-inflicted scratching that could create vulnerable sites,” she said.
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