Valco's engineers developed the drill in a matter of months, and then partnered with startup IsoTherapeutics in nearby Angleton, TX, to formulate the radioactive solution. IsoTherapeutics was founded in 2005 by two veterans of Dow Chemical who set out to develop "radiopharmaceuticals"--radioactive compounds designed to shrink tumors. They combined a radioisotope called yttrium-90 with a proprietary formula that prevents the compound from traveling beyond the tumor. The drill makes several tiny holes in the bone surrounding the tumor, and then delivers microscopic amounts of the compound into each hole. Because yttrium-90 emits high-energy beta particles, "we can cover the whole tumor with a minimal dose," says Keith Frank, cofounder of IsoTherapeutics. And yttrium-90 does not emit gamma radiation, which greatly reduces the risk of radiation exposure to people working with the compound.

The Texas A&M veterinarians who performed Juno's procedure were guided by a high-powered PET/CT scanner. "We were able to see a perfect outline of the leg," Fossum says. After the team injected a contrast agent that binds to glucose in tumors, the PET/CT "showed us where to inject the radioisotope," says Theresa Fossum, a professor of veterinary surgery at the university.

Sixteen dogs have been treated with the experimental procedure at a handful of veterinary schools so far, Frank says. While it's too early to quantify the results, he says, "we always see pain palliation, and we definitely see an increase in survival." He believes the procedure will work on other types of bone tumors, too. IsoTherapeutics is currently in talks with researchers who want to test the technique in women with breast cancer that has metastasized to bone, Frank says.

As for Juno, he was walking without a limp 10 days after his treatment. He'll undergo chemotherapy to attack any latent cancer cells, and then have a follow-up scan in about six months. Owner Dauvalt says she has no regrets, regardless of what the outcome might be. "We have to find different ways of treating cancer," she says. "I felt this was an opportunity not only to help my dog, but possibly to help people."