We don’t normally think of cancer as a contagious disease – but what if we told you there is a contagious cancer that’s thousands of years old? However, this cancer is not caused by the transmission of a virus. These are cancer cells it can be physically passed on between dogs.
In our new study We found that male dogs are four to five times more likely to be infected with the oral and nasal forms than female dogs transmissible venereal tumor in dogs (CTVT). The cancer cells are passed between dogs by sniffing other dogs’ genitals.
CTVT mostly affects the genital regions, leads to the formation of unsightly tumors, and is usually passed on during mating . Sometimes the CTVT cells can affect other areas, such as the nose, mouth, or skin. Although CTVT is a common illness Thousands of dogs on every continent are affected, the oral and nasal versions are rare. Oral and nasal cancers are transmitted when a dog sniffs the CTVT-infected genitals of another dog.
In our database of nearly 2,000 CTVT cases, only 32 involved the nose or mouth. Meanwhile, 84% of dogs with the nasal or oral form were male.
This investigation was carried out on Transmissible cancer groupUniversity of Cambridge, headed by Professor Elizabeth Murchison.
Behavioral differences between the sexes may contribute to this risk. For example, male dogs seem to have a penchant for sniffing or licking female genitals, compared to vice versa. Female genital tumours, being more exposed, may also be more amenable to sniffing and licking than the male genital tumours, which are often hidden within the envelope.
An ancient crab
The most common symptoms of the facial versions of the cancer are sneezing, snoring, difficulty breathing, nasal deformities, or bloody and other discharge from the nose or mouth. With treatment, the vast majority of dogs recover.
This cancer breaks the mold in a different way: CTVT is extremely old. It came from the cells of a live dog several thousand years ago, and passed it on to another dog. Genetic evidence shows it was probably a husky-like animal one Central or North Asia. Since then, the living cancer cells have been hopping from dog to dog like a parasite. If we look at today’s CTVT tumor cells under the microscope, we actually see the cells of the dog that lived thousands of years ago. All current forms of CTVT can be traced back to the same ancient dog.
A global parasite
CTVT affects dog populations around the world but is mostly associated with countries with free-roaming dog populations. It’s not established in the UK – but cases have risen over the last decade, possibly due to the rising popularity of rescue dog adoption from foreign countries.
However, it must be noted that CTVT remains extremely rare in Britain. The chances of the cancer taking hold in the UK are slim as there is no free-roaming canine population.
Better health screening for imported dogs would help diagnose and treat CTVT cases before they have a chance to spread. Raising awareness among veterinarians and owners could also help identify cases early.
Communicable cancers are also found in Tasmanian Devils and molluscs such as mussels and clams. We are not aware of any communicable cancer that would exist in humans.
CTVT is the oldest cancer line known to scientists. It could also help us gain important information about how cancers work in humans. Some of the processes that are striking in CTVT because they are thousands of years old can also go undetected in human cancers.