https://www.youtube.com/watch?v=YerdELZuEhY (Clint's Reptiles "Not All Dogs Have Bones")

A bit of a dry subject to be sure, but I had never heard of infectious cancers before.

In summary: a lot of information on how canines are related to each other. With a short segment how there is an infectious cancer found on dogs that is genetically different from any existing breed and as such could be considered it's own species.