Male dogs more likely to get transmissible cancer on nose or mouth, University of Cambridge scientists find
Male dogs are four to five times more likely than female dogs to be infected with an unusual transmissible cancer on their nose or mouth.
Scientists believe it is because male dogs spend more time sniffing and licking female dogs’ genitalia than the other way around.
Canine transmissible venereal tumour (CTVT) is unusual in that it is infectious - living cancer cells physically transplant themselves from one animal to another during contact.
It commonly affects dogs’ genitals and is typically transmitted during mating, but can affect the nose, mouth and skin.
Researchers at the University of Cambridge reviewed 2,000 cases around the globe, finding 32 affecting the nose or mouth, with 27 of them in male dogs.
Dr Andrea Strakova, in the Department of Veterinary Medicine, carried out the study with colleagues from the Transmissible Cancer Group, led by Professor Elizabeth Murchison.
“We think this is because male dogs may have a preference for sniffing or licking the female genitalia, compared to vice versa,” said Dr Strakova. “The female genital tumours may also be more accessible for sniffing and licking, compared to the male genital tumours.
“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.”
CTVT arose several thousand years ago from the cells of one dog and the cancer survived its death by spreading to new dogs. Now found worldwide, typically in countries with free-roaming dog populations, it is the oldest and most prolific cancer lineage known in nature. It is not common in the UK, but numbers have risen in the past decade, probably due to the importation of dogs from abroad.
“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 Dr Strakova.
These signs of the oro-nasal form of the cancer can include sneezing, snoring, difficulty breathing, nasal deformation or bloody and other discharge from the nose or mouth.
Genital cases of CTVT, meanwhile, occur in roughly equal numbers of male and female dogs.
Tasmanian devils also suffer from transmissible cancers, as do marine bivalves like mussels and clams.
The researchers, who published their work in the journal Veterinary Record, say that studying this unusual long-lived cancer could also be helpful in understanding how human cancers work.
The research was funded by the Wellcome and International Canine Health Postgraduate Student Inspiration Awards from the Kennel Club Charitable Trust.