Sniffing or licking other dogs’ genitals — the common site of canine transmissible venereal tumor — can spread this unusual cancer to the nose and mouth.
A new study has found that male dogs are four to five times more likely than female dogs to be infected with the oronasal form of the canine transmissible venereal tumour.
Researchers believe this is due to behavioral differences between the sexes: male dogs spend more time sniffing and licking female genitalia than the other way around.
Canine transmissible venereal tumor, or CTVT, is an unusual cancer – it is infectious and can spread between dogs when they come into contact. Live cancer cells physically “transplant” from animal to animal.
CTVT generally affects the genitals of dogs and is usually transmitted during mating. But sometimes the cancer can affect other areas like the nose, mouth, and skin.
In the study, researchers looked at a database of nearly 2,000 CTVT cases from around the world and found that only 32 CTVT tumors affected the nose or mouth. Of these, 27 cases involved male dogs.
“We found that a very large proportion of canine transmissible cancer nose or mouth tumors were in male dogs,” said Dr Andrea Strakova from the University of Cambridge’s Department of Veterinary Medicine, first author of the study. ‘article. She carried out this study with colleagues from the Communicable Cancer Group, led by Professor Elizabeth Murchison.
Strakova added: “We think this is because male dogs may have a preference for sniffing or licking female genitalia, compared to the other way around. Female genital tumors may also be more accessible for sniffing and licking, compared to male genital tumors.”
The results are published today in the journal Veterinary file.
CTVT first appeared several thousand years ago from the cells of an individual dog; remarkably, the cancer survived beyond the death of that original dog by spreading to new dogs. This transmissible cancer is now present in dog populations around the world and is the oldest and most prolific cancer lineage known in nature.
CTVT is not common in the UK, although the number of cases has increased over the past decade. It is believed to be related to the import of dogs from overseas. The disease occurs worldwide, but is mostly linked to countries with free-roaming dog populations.
“Although canine transmissible cancer can be diagnosed and treated fairly easily, vets in the UK may not know the signs of the disease as it is very rare here,” Strakova said.
She added: “We believe it is important to consider CTVT as a possible diagnosis of oronasal tumors in dogs. Treatment is highly effective, using the single-agent chemotherapy Vincristine, and the vast majority of dogs heal.”
The most common symptoms of the oronasal form of cancer are sneezing, snoring, difficulty breathing, nasal deformity, or bloody and other discharge from the nose or mouth.
Genital cases of CTVT occur in approximately equal numbers of male and female dogs.
Transmissible cancers are also present in Tasmanian devils and in marine bivalves such as mussels and clams. Researchers say studying this unusual, long-lived cancer could also be useful in understanding how human cancers work.
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