Taking a pet abroad? A screwworm warning worth reading first
What happened
On 3 September 2026, the US Food and Drug Administration authorised two medicines to prevent and treat New World screwworm in dogs and cats. New World screwworm is a parasite. It is the larva of a fly that lays its eggs in open wounds or other openings on warm-blooded animals. The larvae then feed on living tissue. It mainly affects livestock and wildlife, and can affect pets. It affects people only rarely. The authorisation covers Capstar tablets and a generic version, both containing nitenpyram. They can be used in dogs, puppies, cats and kittens weighing at least two pounds, or roughly one kilogram, and aged at least four weeks. Both are over-the-counter products in the United States, in 11.4mg and 57mg tablet sizes, dosed by weight. What makes this notable is that it is the first time prevention products have been authorised for this parasite in pets. Previously authorised medicines only treated an infestation that had already happened. Timothy Schell, director of the FDA's Center for Veterinary Medicine, said the agency was 'addressing a previously unmet need and giving pet owners and veterinarians important tools to protect dogs and cats from NWS infestations'. The FDA says confirmed cases in the United States remain in limited geographic areas, and most pets there are at low risk.
Why this matters
This is an American authorisation about an American situation. So why should a UK reader care? Because a growing number of people travel with their pets, or move abroad with them, or bring animals back from overseas. Screwworm is not present in the UK. It is found in parts of Central and South America and the Caribbean, and the current situation in the southern United States is being actively managed by the US authorities. If you are taking a dog or cat to an affected region, or through one, this is the kind of thing worth raising with your vet before you go rather than after you arrive. There is a second reason. Screwworm can, rarely, affect humans. It gets in through an open wound. Anyone travelling to affected areas with a cut, a graze, a healing wound or a recent surgical site should keep it clean and covered. That is sensible advice anywhere warm and humid, for a whole range of reasons. And the practical point that applies to everyone: medicines for pets, like medicines for people, are licensed country by country. An over-the-counter product in one country may need a prescription somewhere else, or may not be available at all.
What the evidence actually says
Some care is needed in how this is read. An Emergency Use Authorization is not the same as a full licence. It is a mechanism that allows products to be used during a specific situation, based on the evidence available at the time. It reflects urgency as well as evidence. The FDA is measured about the current risk. It says confirmed cases in the United States remain in limited geographic regions, and that most domestic pets are at low risk. The animals needing watching are those in affected areas, or travelling to regions where the parasite is established. This authorisation applies in the United States. It does not change what is licensed or available in the UK. Veterinary medicines here are regulated by the Veterinary Medicines Directorate, and your vet will advise on what is appropriate and legal for your animal. It is also worth being clear about what nitenpyram does. It is an insecticide used in pets, best known for killing fleas quickly. This authorisation extends its use to this specific parasite in this specific situation. It is not a general-purpose travel treatment, and it is not a substitute for the routine parasite prevention your vet recommends. Finally, screwworm is a serious problem for animal welfare and farming, but human cases are uncommon. Nothing here suggests travellers are at meaningful risk of infestation from ordinary travel.
Practical advice
If you are travelling with a pet, plan early. Requirements often take weeks or months to complete. Speak to your vet well in advance. Ask specifically about parasite risks at your destination, not just the paperwork. Check the official rules for taking a pet abroad on GOV.UK, and the entry requirements of the country you are visiting. Rules differ by destination and can change. Rabies vaccination and tapeworm treatment requirements are the ones most often missed, and getting them wrong can mean your pet is refused travel or quarantined. While you are away, check your pet daily for wounds, and keep any cut, graze or surgical site clean and covered. Untreated wounds are how this particular parasite gets in. Get veterinary help quickly if you see maggots in a wound or notice a foul smell from a wound or body opening. The FDA highlights both as signs to act on immediately. For yourself: cover your own cuts and grazes, especially in warm, humid places, and see a doctor if a wound becomes painful, smelly or does not heal. And do not buy veterinary medicines from unregulated online sellers abroad. Dosing is by weight, and the wrong dose can harm a small animal.
What to know
On 3 September 2026 the US FDA issued an Emergency Use Authorization for Capstar (nitenpyram) tablets and a generic version, to prevent and treat New World screwworm in dogs and cats weighing at least two pounds and aged at least four weeks. It is the first time prevention, rather than just treatment, has been authorised for this parasite in pets. The FDA says US cases remain in limited areas and most pets there are at low risk. Screwworm is not present in the UK, and this authorisation does not change UK availability. If you are travelling with a pet, speak to your vet early, check GOV.UK pet travel rules and the destination's requirements, keep wounds clean and covered, and seek veterinary help immediately if you see maggots or smell a foul odour from a wound. Sources: US Food and Drug Administration, 'FDA Issues Emergency Use Authorization for Drugs to Prevent and Treat New World Screwworm in Dogs and Cats', 3 September 2026, https://www.fda.gov/news-events/press-announcements/fda-issues-emergency-use-authorization-drugs-prevent-and-treat-new-world-screwworm-dogs-and-cats ; US Department of Agriculture APHIS, 'Current status of New World Screwworm', accessed 7 September 2026, https://www.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/stop-screwworm/current-status ; GOV.UK, 'Taking your pet abroad', accessed 7 September 2026, https://www.gov.uk/taking-your-pet-abroad This article is for general information and does not replace advice from a vet, doctor, pharmacist or other qualified professional. Speak to your vet about medicines and parasite prevention for your animal, and to a healthcare professional about your own health.
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