I recently ran across an updated research article about infectious facial cancer in Tasmanian devils, also known as devil facial-tumor disease, DFTD.

Devils are the marsupial equivalent of hyenas--noisy, aggressive, smelly carnivores who are also scavengers. Of course, their reproductive biology is completely different. Female devils gives birth to 50 young, which then crawl into her pouch and vie for one of four nipples--meaning that only four of the young survive.

The spread of tumor-like facial lesions in this species was first noticed in 1996. The tumors are transmitted via bite wounds sustained during fights. Not only do they cause permanent damage to the animal's face, the disease is eventually fatal. Many devils lose their teeth and starve to death. Though the total population of this species is estimated to be in the tens of thousands, the mortality rate from this strange cancer has been as high as 100% in some populations. In May 2008, the Australian government announced the Tasmanian devil as endangered.

I searched the Web to review photos of this condition and found one of a devil being examined under anesthesia by Dr. Peter Holz, one of the vets who contributors to our book! (Peter wrote about Patch, the hobby falcon.)

Initially, scientists thought the tumor was caused by a virus. Then environmental toxins were thought to play a role. Now facial tumors in devils are considered to be neuroendocrine in origin, one of a handful of "parasitic cancers" in which susceptibility to the infection depends largely on genetic variability--or lack thereof.

The latest research shows that there are at least three genetically different groups of Tasmanian devils. Genetic variability determines the extent of the immune reaction to foreign cells.

One group of devils succumbs to the tumors quickly because their genetic diversity is low and the cancer cells are not recognized as foreign. A second group is more genetically diverse and appears to be resistant. A third falls somewhere in between and could be helped by a vaccine made of the tumor cells. The Australian government is supporting the research into the vaccine, while also working with zoos and wildlife centers to establish a captive breeding population by capturing young devils before they reach the age of fighting with each other.

See also Save The Tasmanian Devil

All animals require good genes to be healthy. When populations become in-bred, whatever the reason, they become more susceptible disease, as in the case of facial cancer in Tasmanian devils. I'm hopeful the vaccine and breeding program will work. But other environmental factors or stressors related to habitat loss may also play a role.