06/12/2026
New World Screwworm Awareness
New World Screwworm, also called NWS, is a serious parasite that can infest open wounds in animals. While cases are not currently something we want owners to panic about, it is important to know what to watch for and to contact a veterinarian quickly if you notice a wound with unusual drainage, a foul odor, visible larvae, or sudden worsening.
According to the FDAโs current veterinary guidance, the products authorized or conditionally approved for treatment of NWS in dogs and cats include:
For dogs:
Credelio Quattro-CA1
Credelio
NexGard
Nitenpyram tablets
For cats:
Credelio CAT
NexGard COMBO
Nitenpyram tablets
These products should only be used under the direction of a veterinarian when NWS is suspected or diagnosed. If you notice a concerning wound on your pet, please do not try to treat it at home. Call our clinic so a veterinarian can evaluate your pet and decide the safest and most effective treatment plan.
Information referenced from the FDAโs New World Screwworm guidance for veterinarians, current as of June 11, 2026.