In an attempt to provide clients with a way to improve the quality of life of a dog diagnosed with osteosarcoma, researchers at the University of Illinois at Urbana-Champaign are conducting studies on the effects of using pamidronate as a palliative treatment in conjunction with radiation and chemotherapy. Bisphosphonates, a category of drugs that protects bones and includes pamidronate, have been used successfully for the pain control of bone metastases in humans for several years, said William Dernell, DVM, MS, DACVS, associate professor of oncology at Colorado State University.

Pet owners who do not want to amputate an animal’s limb for financial or emotional reasons should have options to improve their animal’s quality of life, said Timothy Fan, DVM. “If people don’t have the money for everything that doesn’t mean that they should have nothing available to them,” he explained. “We want to help dogs feel better while they’re still alive.”

Fan and Louise Philippe de Lorimier, DVM, have conducted several studies using pamidronate, a drug used to reduce breakdown of bones, on client dogs that have osteosarcoma. And he has seen “meaningful responses,” said Fan, who has seen lame dogs come into the clinic and, within two to three weeks of treatment, walk again. “You see a dramatic difference,” he said.

Fan and Lorimier recommend giving pamidronate in conjunction with chemotherapy and radiation. Fan does not recommend using the drug alone and Dernell agreed. “Practitioners need to be cautious about recommending pamidronate alone,” Dernell said. “They should recommend standard of care first, with an option to add the bisphosphonates in if they [clients] do not elect surgery and chemo.”

Dernell referred to several veterinary centers that have used the drugs for bone metastases over the last five years with subjective evidence of success along with a few clinical cases. “Biologically it makes sense to combine the bisphosphonates with radiation since they both work on bone pain alone, but with different mechanisms of action so they should be additive in effect,” he said, and added, “but the data is not there yet.”

Fan said that dogs enrolled in his study showed a decreased need for oral analgesics and seemed to enjoy a higher quality of life. Osteosarcoma symptoms in dogs are similar to those seen with human beings, Fan said. He believes that the new research, which was presented at the ACVIM meeting in June, will some day be applied to human cancer treatments. Although the life expectancy for the dogs does not improve beyond the current one-year prognosis, dogs are freed from the pain associated with the aggressive cancer, Fan said. He cited results from his last study, which was conducted on 41 dogs between November 2004 and February 2005.