There is a transmissible dog tumor which originated with handwave wolves. Apparently there are possibly others. (TIL!) https://en.wikipedia.org/wiki/Canine_tra

There is a transmissible dog tumor which originated with handwave wolves. Apparently there are possibly others. (TIL!) https://en.wikipedia.org/wiki/Canine_transmissible_venereal_tumor https://en.wikipedia.org/wiki/Canine_transmissible_venereal_...