If you love to kiss your dog, then you may be getting slightly more than just dog drool ... you may be getting some retroviruses, too!
Intriguingly, the scientists discovered a novel group of retroviral material in dogs that is highly similar to endogenous retroviruses seen in humans. They belong to a type of virus known as gammaretroviruses, the most frequent type found in mammals to date.
This specific group of retroviruses seems to have invaded the dog genome relatively recently. This suggests that dogs and humans may have passed these germs to each other due to close interactions during our millennia of history together, a phenomenon known as "lateral transmission." It remains uncertain how such transmission might have occurred — perhaps from wet doggie kisses, for instance.