NWS Inspection Certificate for Pet Dogs to Mexico: How to Complete It Correctly

As of August 2026, Mexico requires a New World Screwworm (NWS) Inspection Certificate for Pet Dogs Moving (Exporting) from the United States to Mexico when a pet dog travels from the U.S. to Mexico. According to the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) pet-travel page for Mexico (last modified 27 October 2026), the rule took effect on 3 August 2026, the certificate must be issued by a USDA-accredited veterinarian no more than five days before entry, and it does not need APHIS endorsement. Last checked: November 2026.

This guide walks owners and accredited veterinarians through completing the form correctly so SENASICA officers at Mexico’s Agricultural and Livestock Health Inspection Office (OISA) can accept it. For the broader health-certificate picture for Mexico (zoosanitary papers beyond NWS), see our related guide on health certificates for dogs traveling to Mexico.

What the NWS inspection certificate is

New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae feed on living tissue. After detections in the United States, Mexico updated entry rules for several species. For pet dogs, APHIS states that Mexico requires NWS inspection documents effective 3 August 2026, and that improper or missing paperwork can mean denial of entry or a hold at the border.

The certificate is a bilingual (English/Spanish) inspection form completed by a USDA-accredited veterinarian after examining the dog. It is separate from CDC dog-import rules for returning to the United States and separate from Animal Passport’s muzzle-biometric livestock identity product.

Who must complete it—and who does not

• Required: Domestic dogs (Canis lupus familiaris) originating in and proceeding from the United States to Mexico under SENASICA HRZ combination 007-35-61-USA-USA, as published by APHIS.
• Issuer: A USDA-accredited veterinarian only. APHIS’s veterinarian instructions say the form is issued directly by that veterinarian and given to the traveler; APHIS endorsement is not required.
• Not for cats: APHIS states pet cats do not need this NWS dog certificate (or a health certificate) to enter Mexico; they are inspected by SENASICA on arrival. Do not add a cat to the dog form—doing so invalidates the document.
• Pet birds: Birds use a different NWS addendum plus an APHIS-endorsed bird health certificate; do not use the dog form.

Five-day timing window (critical)

APHIS’s instructions for accredited veterinarians require the Date of Issue and NWS Inspection in DD/MM/YYYY format. That date must fall within five days prior to entry. Example from APHIS: if the dog enters Mexico on the 6th, the form cannot be completed before the 2nd. Outside that window, Mexico may deny entry or hold the dog until the certificate can be validated.

Plan the vet appointment for the few days immediately before the border crossing or flight arrival—not a week early “to be safe.”

How to complete the certificate field by field

The following steps follow USDA APHIS’s published instructions PDF for the NWS Inspection Certificate for pet dogs (hosted on APHIS’s Azure CDN and linked from the Mexico pet-travel page).

1–5. Clinic identity and place of issue

1. Name of the veterinary clinic, office, or hospital.
2. Full clinic address.
3. Clinic telephone number.
4. Clinic email.
5. Place of issue: city and state of the clinic.

6. Date of issue and NWS inspection

Use DD/MM/YYYY. Confirm the date is inside the five-day window before the planned Mexico entry date.

7. Owner details

Complete the owner fields exactly as the traveler will present identification at OISA.

8. Pet data (dogs only)

• Species must remain dog. Do not line out and write another species.
• The “Identification” field means the pet’s name.
• Mexico does not require a microchip for this certificate, but a microchip number may be listed in the optional column.

9. Certification statements

APHIS describes an either/or certification. Line out the statement that does not apply. Fill treatment information only if the dog was diagnosed with screwworm, held in isolation, and treated until free—not for routine preventatives.

10–11. Veterinarian name and accreditation number

Write the full name and USDA accreditation number exactly as listed in the National Veterinary Accreditation Program (NVAP). APHIS warns that border officials validate these fields; mismatch or illegible entries can cause denial or a hold.

12. Signature rules

Digital signatures are not accepted. APHIS requires a handwritten signature in non-black ink (for example blue or red) so the signature color differs from the printed certificate text.

13. Give the original to the traveler

The accredited veterinarian issues the form directly to the owner. The owner must present the original to Mexican border officials. No APHIS endorsement step is part of this dog NWS certificate workflow.

What happens at the Mexican border (OISA / SENASICA)

APHIS summarizes that on entry with a clean carrier, the traveler proceeds to OISA for SENASICA inspection. Officers verify that the dog:

• Shows no signs of infectious or contagious disease,
• Is free of ectoparasites,
• Has no fresh wounds or wounds in the process of healing, and
• Has a valid NWS Inspection Certificate issued within five days.

If ectoparasites are found, APHIS notes the owner must arrange treatment; tick samples may be taken and the pet held until laboratory results clear Mexico’s concern. Dirty carriers, disposable bedding, toys, or excess food can trigger disinfection and destruction of those items; only food for the day of arrival is permitted.

Common rejection risks (from APHIS reminders)

• Missing certificate or date outside the five-day window.
• NVAP name or accreditation number that does not match official records.
• Digital or black-ink signatures that blend into the form text.
• Cats or other species written onto the dog form.
• Dog arrives with ectoparasites or open/healing wounds.

APHIS’s August 2026 GovDelivery bulletin asked accredited veterinarians to review the certificate carefully because incomplete paperwork was already causing delays and rejections at Mexican ports.

Returning to the United States is a different rulebook

As of 22 November 2024, APHIS treats Mexico as screwworm-affected for U.S. dog import purposes. Dogs returning from Mexico must meet APHIS screwworm-freedom certification for U.S. entry, and the Centers for Disease Control and Prevention (CDC) remains the primary authority for dog imports into the United States. Do not assume the outbound Mexican NWS certificate alone covers re-entry.

Where Animal Passport fits

Animal Passport is a digital livestock identity system that uses muzzle biometrics, dental age estimates, and body-condition scoring for farm animals. It is not a Mexican import permit, not an APHIS endorsement, and not a substitute for the NWS Inspection Certificate. Keep official travel paperwork on the APHIS and SENASICA path; use Animal Passport when you need durable livestock identity records.

For more travel and identity explainers, browse the Animal Passport journal or the product overview at animalpassport.co.

Checklist before you leave for the border

1. Book a USDA-accredited veterinarian inside the five-day window.
2. Confirm NVAP name and number spelling before the appointment.
3. Leave with the original ink-signed certificate (non-black ink).
4. Use a clean carrier; pack only that day’s food.
5. Expect OISA inspection for parasites and wounds on arrival in Mexico.
6. If you will return to the U.S., separately confirm current CDC and APHIS dog-import rules.