FROM THE TVMA
FDA Has Not Authorized Medicated Feed for NWS; What Veterinarians Need To Know
With New World Screwworm (NWS) now confirmed in Texas, TVMA has received questions from members about producer interest in using ivermectin in feed as a prevention tool. TVMA has prepared this guidance to help members respond accurately to those questions and advise clients appropriately.
The guidance covers what FDA has and has not authorized for NWS prevention and treatment in cattle, why medicated feed is not currently an option and how to advise clients who are asking about it. It also includes links to the most up-to-date list of products authorized by the FDA.
| TVMA NEW WORLD SCREWWORM RESOURCE PAGE |
| TVMA's full guidance on ivermectin, medicated feed and NWS is one of many NWS resources available on the TVMA NWS Resource Page. |
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Online Course To Expand Certified NWS Inspectors Across Texas
Last week, Governor Greg Abbott announced the launch of a free online New World Screwworm (NWS) inspector training course, developed by Texas A&M AgriLife Extension in partnership with the U.S. Department of Agriculture (USDA), the Texas Animal Health Commission (TAHC) and the Texas Parks and Wildlife Department (TPWD).
TVMA has confirmed that the course has been approved by the Texas Board of Veterinary Medical Examiners (TBVME) for four hours of continuing education (CE) credit for Texas veterinarian licensees.
| Free NWS Inspector Training Available |
The course is an online, modular program covering:
- New World Screwworm biology and life cycle
- Surveillance and reporting requirements
- Species-specific inspection and treatment protocols
- Agency roles and responsibilities
- Movement permitting requirements
Licensed veterinarians who pass the final exam may apply to become a TAHC Certified NWS Inspector, authorized to issue official NWS Treatment/Movement Certificates for the lawful movement of livestock out of infested zones. |
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Veterinarians Encouraged To Educate Clients on Clinical Signs, Prevention and Treatment
The Texas Animal Health Commission (TAHC) has issued guidance for veterinarians on New World Screwworm (NWS) as cases continue to be confirmed in Texas. The guidance focuses on companion animals and covers movement requirements, reporting, sample collection and treatment.
| Key Points From The Guidance |
- Pet owners may currently transport companion animals out of infested zones without movement permits or health certificates, though large groups may be asked for verification that animals have been monitored for symptoms.
- Early detection is critical. Report all suspected NWS cases immediately to the TAHC veterinarian on call at 1-800-550-8242 or to your TAHC region office.
- If NWS or myiasis is suspected, samples should be collected and submitted for official identification. Sample collection protocols are available on the TAHC website.
- Approved treatment products are available. Visit the U.S. Food and Drug Administration (FDA) webpage for the current list of authorized and conditionally approved animal drugs for NWS prevention and treatment.
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Click here to read the full TAHC guidance, including additional resources for companion animal practitioners.
For additional NWS resources, visit the
TVMA NWS Resource Page.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Cases Now Confirmed Across Multiple Texas Counties; Full Situation Update for Practitioners
As New World Screwworm (NWS) continues to spread across Texas, TVMA is providing members with a comprehensive update on confirmed cases, the state and federal response, available treatments and movement restrictions affecting Texas animals.
| Confirmed Cases in Texas |
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As of June 12, the following NWS detections have been confirmed by the U.S. Department of Agriculture (USDA) to date:
- June 3 — three-week-old calf, Zavala County
- June 5 — one-month-old calf, Zavala County
- June 7 — calf in La Salle County; dog in Lea County, New Mexico (identified by veterinarians in Andrews County, Texas)
- June 8 — goat, Gillespie County; calf, La Salle County
- June 9 — calf, Edwards County
- June 11 — goat, Edwards County; bovine, Zavala County
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State and Federal Response
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USDA and the Texas Animal Health Commission (TAHC) have formed a unified Incident Command Team and deployed response personnel to affected areas. Key response actions include:
- Establishing a 20-km infested zone around detections with hold orders, movement controls and heightened surveillance. Click here for the most up-to-date zone maps.
- Deploying ground release chambers for targeted sterile fly release in affected areas, in addition to 4 million sterile flies per week already being released aerially. The sterile fly dispersal facility at Moore Air Base in Edinburg is fully activated.
- Increasing trapping for NWS flies along the border and just outside the dispersal area
- Implementing NWS surveillance and management strategies in wildlife
- Conducting targeted outreach to local producers, veterinarians and communities Veterinarians can assist in this effort by sharing client-facing education documents such as this one from TVMA.
- Deploying resources from USDA's National Veterinary Stockpile, including treatments, equipment and logistics
USDA is also collaborating with Mexico to enhance surveillance, control animal movement and increase sterile fly releases in affected areas.
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Guidance for Animal Owners and Veterinarians
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Advise clients to check pets and livestock daily for:
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Approved and Authorized Drug Products
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The following products are currently available for NWS prevention and treatment. Visit the FDA webpage on authorized animal drugs for NWS for full prescribing information and extralabel use guidance.
FDA-Approved or Conditionally Approved:
- Dectomax-CA1 (doramectin injectable) — cattle
- Exzolt Cattle-CA1 (fluralaner topical solution) — beef cattle and replacement dairy heifers
- Credelio Quattro-CA1 (lotilaner, moxidectin, praziquantel, pyrantel chewable tablets) — dogs and puppies
FDA Emergency Use Authorizations:
- Credelio (lotilaner chewable tablets) — dogs and puppies
- Credelio CAT (lotilaner chewable tablets) — cats and kittens
- Ivomec (ivermectin injectable solution) — cattle (with restrictions; see FDA page)
- NexGard (afoxolaner chewable tablets) — dogs and puppies
- NexGard COMBO (esafoxolaner, eprinomectin and praziquantel topical solution) — cats and kittens
- F10 Antiseptic Wound Spray with Insecticide — cattle, horses, hoof stock, raptors, wild and pet birds, captive wild/exotic/zoo mammals (not for domestic dogs and cats)
- F10 Antiseptic Barrier Ointment with Insecticide — cattle, horses, hoof stock, raptors, wild and pet birds, captive wild/exotic/zoo mammals (not for domestic dogs and cats)
- Negasunt Powder — cattle, swine, goats, sheep, horses, donkeys, equids, captive wild/exotic/zoo mammals; for use by government agency employees or by/on order of a licensed veterinarian in infested/surveillance zones (not for domestic indoor pets)
- Dectomax/Dectomax-CA1 (doramectin injection) — dairy cattle, horses (1 year and older), swine, sheep (non-lactating) and deer
- Nitenpyram Tablets — dogs, puppies, cats, and kittens 2 lbs or greater and 4 weeks of age and older
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Animal Movement and Travel Restrictions
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International:
- USDA suspended imports of live cattle, horses and bison from Mexico on May 11, 2025. Horses may still be flown into designated U.S. import centers under strict health and quarantine requirements.
- All dogs entering or re-entering the U.S. from Mexico must meet U.S. Animal and Plant Health Inspection Service (APHIS) requirements for screwworm freedom certification. See the APHIS dog import page for details.
- Mexico halted imports from all U.S. states of cattle, wild ruminants, equines, sheep and goats, swine (reproduction), ferrets and birds on June 5, 2026. Pet dog travel to Mexico resumed under previously established criteria on June 10.
- On June 5, the Canadian Food Inspection Agency announced it would temporarily limit imports of animals, including livestock and horses, that originate from or were present in Texas within 21 days of arriving at the U.S.-Canada border.
- All NWS-related international restrictions are updated in real time on the APHIS International Regulations page (non-pet species) and the APHIS International Pet Travel page (pet species).
Interstate:
Eighteen states have implemented entry restrictions for animals from affected areas, including Arkansas, Colorado, Delaware, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Minnesota, Missouri, Montana, North Dakota, Oregon, Tennessee and West Virginia. If you or your clients are moving animals out of Texas, check current requirements at Interstate Livestock before doing so.
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Food Safety
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The U.S. food supply is not affected. NWS does not infest meat, fruits, vegetables or other food sources. USDA's Food Safety and Inspection Service inspects all eligible commercial animal species, and any evidence of NWS infestation would be identified and the affected product would not enter the food supply.
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If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
As Foreign Countries Update Requirements, APHIS Webpages Are the Most Current Source of Information
The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has provided the following guidance to veterinarians as practices field client questions about animal travel restrictions related to New World Screwworm (NWS).
APHIS is actively working with U.S. trading partners, including Mexico, to clarify and update travel restrictions as the NWS situation develops. Because requirements are changing quickly, APHIS is directing veterinarians and their clients to its websites as the most current and accurate source of information.
| APHIS Resources for Veterinarians and Clients |
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Each page will be updated will be updated as soon as new information is received from trading partners. APHIS asks that veterinarians and clients not contact USDA APHIS offices directly for country-specific restriction information, as the agency does not have information beyond what is posted to those pages. |
| Interstate Livestock Movement |
Veterinarians writing health certificates also should be aware that interstate livestock movement requirements may change as NWS cases are confirmed in Texas.
For the most current interstate movement requirements by state, click here. |
TVMA will continue to share updates as they become available. For additional NWS resources, including the latest on confirmed cases in Texas, visit the TVMA NWS Resource Page.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Pet Owners Should Exercise Caution in Travel to Mexico as Situation Evolves
The U.S. Department of Agriculture (USDA) has issued a New World Screwworm notice halting exports of the following animal species from the United States to Mexico:
| Affected Species |
• Cattle (slaughter and reproduction)
• Wild ruminants (non-bovine)
• Equine (slaughter, breeding/work and sport/exhibition/transit)
• Sheep and goats (slaughter and reproduction)
• Pet dogs
• Swine (reproduction)
• Ferrets (commercial and pets)
• Songbirds, ornamental birds and raptors (commercial and pets) |
| Veterinarian Guidance for Pet Dogs Returning from Mexico |
| As of this writing, pet dogs may still return to the United States from Mexico but must meet USDA Animal and Plant Health Inspection Service (APHIS) requirements for screwworm freedom certification upon re-entry. Full re-entry requirements are available on the APHIS dog import page. |
Notably, USDA also has confirmed a case of NWS in a New Mexico-based dog at a veterinary clinic in Andrews County in West Texas. This is the first confirmed case of NWS in New Mexico. Early reports indicate the dog recently had traveled to Mexico, making it a movement-related case, and epidemiological investigations are ongoing.
This case underscores why clients who travel regularly to Mexico with their dogs should exercise caution. Requirements could change as the situation develops, and pet travel to Mexico warrants careful consideration until further notice.
| The Latest on Quarantine Zones in Texas |
| There is currently a quarantine in place in parts of La Salle, Uvalde, Webb and Zavala counties. According to Texas Animal Health Commission (TAHC) Executive Director Orders, all warm-blooded animals in a zone may not move out of the zone without prior authorization from the TAHC. |
For more information on moving animals out of quarantine zones, visit the TAHC’s NWS Page.
For additional NWS resources for veterinarians, visit the TVMA NWS Resource Page.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
First Confirmed U.S. Case of New World Screwworm Detected in Zavala County
On June 3, the first case of New World Screwworm (NWS) was confirmed in a three-week-old calf in Zavala County, Texas. Other than an isolated incursion into the Florida Keys in 2016, this is the first detection of NWS in the United States since it was eradicated in 1966. State and federal animal health officials are aware and responding.
This is not a reason to panic. Federal and state agencies, including the U.S. Department of Agriculture (USDA) and the Texas Animal Health Commission (TAHC), along with livestock and veterinary industry groups, have been preparing for this moment for more than a year.
Sterile fly dispersal operations are already underway in South Texas, surveillance infrastructure is in place, and approved treatments are available. The U.S. eradicated this pest before, and the response tools available today are significantly more advanced than they were in 1966. TVMA is in close contact with TAHC and will continue to provide updates as the situation develops.
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Your Role in Detection and Response
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Watch for Signs and Report Immediately
Whether you are a small or large animal practitioner, examine all animals closely for wounds, openings in the skin, suspicious flies or maggots in living tissue. This applies to companion animals as well as livestock. If you suspect a case, do not move the animal and report it immediately to the following:
- TAHC veterinarian on call: 1-800-550-8242
- TAHC region office: 956-568-5741
- Texas USDA: 512-202-1181
- For wildlife suspicions, contact Texas Parks and Wildlife at 512-389-4505.
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Talk to Your Clients
Your clients are looking to you for guidance. TVMA’s pet owner guide and TAHC’s livestock-focused flyer give pet owners and producers plain-language information on what to watch for, what to do and who to call. Share them at the front desk, in your waiting room and through your practice’s communications.
Help TVMA Track the Response
If you suspect a case or encounter something unusual, please contact TVMA in addition to the reporting numbers above. We want to ensure our members’ experiences are part of the broader response picture.
For the latest updates, visit the TVMA NWS Resource Page and screwworm.gov.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
New World Screwworm Response Continues Near Del Rio and Eagle Pass
New World Screwworm (NWS) has not been detected in Texas or anywhere in the United States. Reports circulating this week suggesting a detection one mile from the border are not accurate. As of June 1, the closest confirmed case is 25 miles from the Texas border in Coahuila, Mexico, nearest to Del Rio and Eagle Pass. There are now more than 2,000 active animal cases in Mexico and more than 26,000 total cases since November 2024.
The U.S. Department of Agriculture (USDA) and the Texas Animal Health Commission (TAHC) are actively dispersing sterile NWS flies along the border, with more than 123 million sterile flies released in Texas as a precautionary measure as of late May. The sterile fly dispersal grid has expanded northward along the Texas border twice this year, and TAHC is increasing its presence in Maverick, Kinney and Val Verde counties for local outreach and preparedness. These are proactive measures, not a response to a confirmed detection in the U.S.
| What Veterinarians Should Do |
Regardless of your practice type, examine animals closely for wounds, openings in the skin, suspicious flies or maggots in living tissue. If you suspect a case, do not move the animal. Report immediately:
- TAHC veterinarian on call: 1-800-550-8242
- TAHC region office: 956-568-5741
- Texas USDA: 512-202-1181
- For wildlife suspicions, contact Texas Parks and Wildlife at 512-389-4505.
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TVMA’s
pet owner guide and the
TAHC's livestock-focused flyer can educate your clients on what to watch for, what to do and who to call. Share them at your front desk, in your waiting room or through your practice’s communications.
For more resources on NWS, visit the TVMA NWS Resource Page. For the most up-to-date information on NWS progress and response, visit the USDA APHIS NWS Response Page.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Dr. Pancho Hubert Represents Texas Veterinarians at Regional NWS Briefing
On Monday, TVMA President Dr. Pancho Hubert joined Rio Grande Valley county judges and state and industry leaders in Weslaco for a joint press conference on the New World Screwworm (NWS) threat. The event was organized by the county judges of Hidalgo, Starr, Willacy and Cameron counties and brought together representatives from the Texas Animal Health Commission, represented by TVMA member and former board member Dr. Sandra Leyendecker, as well as the Department of State Health Services, the Texas Parks and Wildlife Department, the Texas Farm Bureau and the Texas and Southwestern Cattle Raisers Association.
Dr. Hubert emphasized that NWS is not solely a livestock concern. Dogs and cats are also susceptible, and companion animal veterinarians will play a critical role in early detection and response. He highlighted TVMA's online NWS resource page and the continuing education workshop offered at this year's Annual Conference as steps the association has taken to prepare its members.
Click here to watch coverage of the press conference from KRGV. Click here to see Dr. Hubert’s remarks.
Visit TVMA's NWS resource page for the latest updates and guidance for your practice.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Latest Updates on NWS Activity, Federal Response and Your Role in Detection
Though New World Screwworm (NWS) has not been detected in the United States, it has been found in two Mexican states bordering Texas, with the nearest case being 62 miles south of McAllen.
This week, TVMA testified before the Texas Senate Committee on Water, Agriculture, and Rural Affairs, stressing that every veterinarian in Texas, including companion animal veterinarians, will play a critical role in detection and response.
| Mexican NWS Cases By the Numbers |
Of the 206 active cases confirmed in Nuevo León and Tamaulipas as of May 9 and the 1,717 active cases across Mexico, the affected animals include:
- 913 cattle
- 455 dogs
- 136 swine
- 88 horses
- 1 cat
- 1 endangered howler monkey in Chiapas (the first confirmed wild-animal death)
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| The U.S. Response |
In the past 10 months, the United States has taken the following steps to prepare for NWS:
- Closed southern livestock ports since July 9, 2025
- Opened a new sterile fly dispersal facility at Moore AFB in Edinburg in February
- Broke ground on a new sterile fly production facility in South Texas on April 17, targeting production of 100 million sterile flies per week by November 2027 and over 300 million per week by 2028
- Issued five Food and Drug Administration (FDA) emergency use authorizations for animal drugs since November 2025 (Credelio, Credelio CAT, Ivomec, NexGard, NexGard Combo)
- Announced a $100 million NWS Grand Challenge Funding Pool to accelerate sterile fly production and response
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| Veterinarians’ Next Steps |
Regardless of whether you are a small or large animal veterinarian, you are on the frontline in identifying NWS and educating your clients. Visit TVMA's NWS resource page for the latest updates and guidance for your practice.
The resource page includes a client handout explaining what NWS is, what to watch for and when to call a veterinarian. Share it with clients, post it in your clinic, or distribute it through your practice’s social media channels to help educate the public. |
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.
Source: The Bird Bath, a veterinary industry newsletter. Read the full post here.
New Facility Will Be Key To Fighting New World Screwworm
Last week, state and federal agencies broke ground on a New World Screwworm (NWS) sterile fly production facility at Moore Air Base in Edinburg. The project brings together U.S. Department of Agriculture (USDA) leadership, the U.S. Army Corps of Engineers and state officials to expand the nation’s sterile fly production capacity.
Earlier this year, officials opened a sterile fly dispersal facility at the same site, but the production of new flies there will be a critical tool in fighting the pest as it migrates northward. Though no cases have been found in Texas, the nearest known case was found on April 19 on a one-year-old calf 62 miles from the border in Marin, Nuevo Leon, Mexico. Recently, another case was located on a dog 90 miles from the border.
For veterinarians, the update reinforces the importance of routine animal monitoring, proactive wound-prevention guidance and early client engagement through established veterinarian-client-patient relationships. While current NWS activity remains in Mexico, the Texas Animal Health Commission (TAHC) and USDA continue active preparedness planning with industry partners to mitigate risk and protect Texas livestock.
Click here to see the most up-to-date information for veterinarians.
To read TAHC’s full press release on the new sterile fly production facility, click here.
If you have any questions, you may contact TVMA General Counsel/Director of Government Relations Trent Hightower at 512-610-6656 or thightower@tvma.org.