Sniffing Butts Can Put Male Dogs At Four Times Risk Of Certain Cancers

Sniffing or licking dogs' private parts can spread some cancers to the mouth and nose. 


Rachael Funnell

Digital Content Producer

clockJul 6 2022, 16:50 UTC
Canine Transmissible Venereal Tumor
Canine Transmissible Venereal Tumor is the oldest cancer lineage known from nature. Image credit: Tara Patta /

A venereal cancer has persisted among canine kind for thousands of years, spreading through mating to cause genital tumors and through the sniffing and licking of butts 'n’ stuff, leading to tumors in the nose and mouth. While genital tumors seem to appear in male and female dogs equally, new research has found that male dogs are four times more likely to develop tumors of this cancer in the oro-nasal region.

Canine Transmissible Venereal Tumor, or CTVT, is an infectious disease as living cancer cells physically transplant themselves from the tissue of one animal onto another. In the case of dogs, this can occur during mating or when a dog sticks their snoot and tongue into the groin of another.


To explore why the cancer seems to affect the nose and mouth of male dogs more compared to females, a study published in the journal Veterinary Record reviewed around 2,000 cases of CTVT in dogs from around the globe. The sample included 32 dogs whose CTVT tumors were in the nose and/or mouth, 27 of which were male dogs.

“We found that a very significant proportion of the nose or mouth tumours of canine transmissible cancer were in male dogs,” said first author Dr Andrea Strakova of the University of Cambridge’s Department of Veterinary Medicine in a statement.

“We think this is because male dogs may have a preference for sniffing or licking the female genitalia, compared to vice versa. The female genital tumours may also be more accessible for sniffing and licking, compared to the male genital tumours.”

CTVT is, arguably, an impressive cancer, being the oldest and most prolific cancer lineage ever detected. Having spread from its host of origin, the contagious cancer has been transmitted among dogs for thousands of years and now exists across much of the globe.


However, the researchers are concerned that as it spreads to areas such as the UK where it is less common, clinicians may be unfamiliar with the disease and therefore find it harder to reach a diagnosis. CTVT is treatable, but only if veterinarians are able to detect it.

“Although canine transmissible cancer can be diagnosed and treated fairly easily, veterinarians in the UK may not be familiar with the signs of the disease because it is very rare here,” said Strakova.

“We think it’s important to consider CTVT as a possible diagnosis for oro-nasal tumours in dogs. Treatment is very effective, using single agent Vincristine chemotherapy, and the vast majority of dogs recover.”

Symptoms of oro-nasal CTVT in dogs include sneezing, strained breathing, snoring, discharge from the nose or mouth which can be bloody, and a deformed nose. If you’re concerned your dog may be exhibiting symptoms of CTVT, speak to your vet for advice.

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