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Cancer can spread between Dogs.

by editor2
August 11th, 2006

There is a type of cancer, called CTVT (canine transmissible venereal tumor) which is transmitted mainly through sexual contacts, but may also be passed on as a dog bites, sniffs or licks the tumor-affected areas, say scientists and vets from University College London (UCL). The cancer is rarely fatal and goes away after three to nine months – however, it is present in the dog long enough for it to pass it on to other dogs.

The researchers say humans do not have to worry as this type of cancer cannot be passed on from dog to people, it only occurs in dogs. It is a type of cancer that can spread from dog-to-dog as if it were an infection.

Professor Robin Weiss, UCL Division of Infection and Immunity, team leader, said “It appears that man’s best friend can be its own worst enemy. Our study shows that CTVT has become a parasite that has long outlived its original host. Our discovery is of much broader significance than simply a disease in dogs.”

“Firstly, CTVT represents the longest-lived cancer ‘clone’ known to science. It contradicts the current view that cancer cells generate more and more mutations and inevitably become more aggressive if untreated.”

“Secondly, recent research in Australia has revealed the existence of a newly emerged tumour in Tasmanian Devils that also appears to be caused by transmissible cancer cells, in this case by biting. Devils are an endangered marsupial species and there are fears that the new tumour might finally kill them off altogether. The methods used at UCL for dogs could help to determine whether the Devil tumour is also a ‘parasitic’ cancer.”

“Thirdly, our findings also show that cancer cells can evade immune responses and CTVT is particularly smart in this regard. On rare occasions cancer cells have been transmitted from one human to another by hiding in organ transplants. Because the recipient is treated with immunosuppressants in order to prevent rejection, the transferred cancer cells can then grow into tumours just like CTVT. That is why people who have suffered from cancer should not become organ donors.”

CTVT was first isolated in 16 dogs in Kenya, India and Italy. Genetic studies showed that in each case the tumor had been passed on by another canine. Further studies on 40 more dogs from around the world indicated that the cancer originated from a single source that has managed to spread worldwide.

After liasing with geneticists and computer experts in Chicago, USA, the scientists believe the cancer appeared between 250 to 1000 years ago – probably in a wolf, Husky or a Shih Tzu.

Unlike most cancers, which with time become more aggressive and genetically more unstable, CTVT is genetically stable and has been around for a very long time. This could change the way scientists view the stability of cancer, allowing for the possibility that as a tumor gets worse it does not necessarily become genetically more unstable.

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