Bio-Rad Laboratories writes that sexually transmitted dog cancer originated 11,000 years ago in “a relatively inbred canine resembling a malamute.” The first documented case of CTVT was identified in London in 1810. Per VCA Hospitals, experts suspect that the ailment resulted from adverse mutations in immune system cells known as histiocytes. Unlike more commonly known cancers, the venereal version didn’t die with the sufferer because when canines spread their love as they’re wont to do, they’re also spreading the disease. And this illness isn’t picky. It affects dogs of any age or breed.

These love tumors might sound akin to the human papillomavirus (HPV), which can cause cauliflower-shaped warts, occasionally leads to cervical cancer, and spreads when two people play a Marvin Gaye song and start moving to the music. But as the CDC observes, HPV usually subsides on its own, and can take years or decades to become cancerous. Dogs don’t have the luxury of human or dog years. When affected canines express their affections doggy style, they transfer cancer directly. They can also contract it through licking, sniffing and biting malignant tumors.

Anatomically, the cancer remains local, developing in a single area and spreading exclusively to the skin of whatever unfortunate dog made contact. Globally, it gets around and is found in 90 countries and on every continent. It’s most prevalent in tropical climates, cropping up in South and Central America, Asia, Africa, and the southern United States — or as we like to call these places, the nether regions of the world.