CTVT in the UK: What Dog Owners Need to Know About the Contagious Cancer Now Spreading Here

A transmissible cancer is spreading among dogs in the UK, and many vets have never seen a case. That's the situation as of November 2026, when veterinary bodies began offering free testing to UK practices in response to a confirmed rise in canine transmissible venereal tumour (CTVT) cases linked to imported dogs.

CTVT is strange, even by cancer standards. It doesn't work the way most cancers do. Instead of arising within one animal's cells, it passes between dogs as a living transmissible cell line, typically through direct contact during mating. The same clonal tumour has been circulating in dog populations for somewhere between 6,000 and 11,000 years, making it one of the oldest known continuously surviving cancers on earth.

That's worth sitting with for a moment.

Why This Is Happening Now in the UK

The rise in cases tracks closely with the increase in dogs imported from countries where CTVT is endemic, including parts of Eastern Europe, Asia, Africa, and Latin America. During and after the pandemic years, dog imports into the UK rose sharply, and the checks on imported animals, while existing on paper, don't screen for CTVT.

The disease has historically been rare enough in the UK that most practising vets here have never encountered it. That's the core problem. A vet who hasn't seen CTVT before may not immediately recognise the external tumours it causes, particularly in their early stages, and may not think to test for it. The free testing initiative announced on November 2 is a direct attempt to close that gap, urging practices to submit samples when they see anything that looks suspicious.

What CTVT Actually Looks Like

The tumours typically appear on or around the genitals, though they can occasionally show up on the nose, mouth, or skin. They tend to be fleshy, irregular, and may bleed or ulcerate. In the early stages they can be easy to dismiss as a minor skin issue, an irritation, or a benign growth.

This is where paying attention to your dog's behaviour matters. Dogs with CTVT in or around the genitals will often lick the area persistently, scoot, or show obvious discomfort during urination or when touched around the hindquarters. If you're already tracking your dog's health and behaviour patterns, that kind of change stands out more quickly than if you're relying on memory. Tailo's episode tracking can log exactly this sort of thing, which makes it easier to show a vet a clear picture of when a behaviour started and how it's progressed, rather than trying to reconstruct a timeline in the consulting room.

The Good News

CTVT is highly treatable. That fact is mentioned explicitly in the November 2 guidance, and it matters because it changes the calculus significantly. A dog diagnosed early has an excellent prognosis. Chemotherapy using vincristine is the standard treatment and has a very high success rate, typically producing complete remission after a course of around four to six sessions.

The concern is late diagnosis, either because an owner didn't notice the tumour, or because a vet didn't recognise it.

What to Actually Do

If your dog was imported from outside the UK, or has had contact with imported dogs, it's worth being more alert to physical changes around the genitals and face. Not paranoid, just attentive.

If you see anything unusual, don't wait to see if it resolves on its own. CTVT tumours can grow quickly and can occasionally spread to other sites if left untreated, though this is less common.

When you go to the vet, be specific about your dog's history. If they came from abroad, or if you don't know their full background, say so. That context is genuinely useful. As of November 2026, UK vets can now access free testing, so there's no cost barrier to getting a suspicious lesion checked.

The Wider Context

The CTVT situation is partly a consequence of how dramatically UK dog demographics shifted after 2020. A lot of dogs came into the country quickly, from a wide variety of places, and the population of vets here didn't have the accumulated clinical experience with diseases that were endemic elsewhere. CTVT is just one example of that gap showing up in practice.

It won't be the last. The American Animal Hospital Association published updated parasite guidelines just last week on October 29, partly in response to emerging threats like the New World Screwworm reaching regions where it hadn't previously been a concern. The pattern is the same: a changing world, faster movement of animals, and clinical knowledge that hasn't quite caught up.

Knowing your own dog, and noticing when something is off, remains one of the more reliable defences you have.