Skip To Content
Cambridge University Science Magazine
CTVT is one of four known transmissible cancers.

CTVT is one of four known transmissible cancers.

One of these cancers is Canine Transmissible Venereal Tumour (CTVT), which is a cancer that is found in dogs. It causes growth of genital tumours and is transmitted between animals via mating. CTVT originated in one dog about 11,000 ago and as since spread around the world. In a new study published in eLife, a team of researchers lead by Cambridge University scientists has tracked the global distribution of CTVT by studying its genetics, revealing how dogs found their way to all corners of the globe along with the humans who domesticated them.

The researchers investigated how the cells of CVTV found in over 400 dogs from 39 countries are genetically related to one another by looking at a part of their DNA called mitochondrial DNA (mtDNA). mtDNA is the genetic code found in a cell’s mitochondria, which is the part of the cell that produces energy for the cell’s metabolism. This type of DNA evolves extremely slowly because it is very crucial for the cell. Therefore, mtDNA sequences from different individuals can be compared to infer how closely related they are – the more dissimilar their mtDNA sequences, the more distantly related they are. From the information gained from the sequences of the mtDNA of the hundreds of tumours, the scientists established that CTVT spread across the world with great speed over the past 2,000 years, presumably in dogs brought along by merchants traveling the world. They could show that the first appearance of CTVT in the Americas dates back to 500 years ago, coinciding with the arrival of the first Europeans.

Another finding of the study was that, while the CTVT tumour cells are not related to the host dog’s body cells, sometimes the tumour cells incorporate fragments of the host dog’s mtDNA into theirs. This is very unusual for mtDNA and has never been observed in other types of cancer. The researchers hypothesize that it may serve to protect the tumour cells from detrimental mutations to their mtDNA, increasing their fitness and making them more likely to be able to spread. It will be very interesting to investigate whether a process like this also occurs in human cancers.

Learn more about how the cancer spread across the globe:

Watch this animation made by about the study by the Cambridge University communications office.

Read the entire study here.

Written by Janina Ander