A link between gender and lymphoma was identified in a study of 1.3 million dogs evaluated over a period of 20 years, according to research presented at the 24th annual Veterinary Cancer Society conference Nov. 3-6 in Missouri. The data corresponds to human studies, which shows that non-Hodgkin’s lymphoma, which is analogous to canine lymphoma, is 50 percent more common in men than women. After recognizing the link, several veterinary oncologists embarked on a study to identify disease similarities between dogs and people to “unravel clues about cancer causation and potentials for cancer prevention,” said Carolyn Henry, DVM, MS, DACVIM, associate professor of oncology at the University of Missouri. The research will be published in the Journal of Veterinary and Comparative Oncology.

“Results of this study showed that intact female dogs were significantly less likely to develop lymphoma than were other gender groups,” Henry said. “As in people, female gender appeared to be protective against the development of lymphoma. … [And] the fact that this protection was only noted in intact females…suggests that further examination of the role estrogen [plays] in lymphoma is warranted.”

Data was collected from the Veterinary DataBase, a consortium of teaching hospitals at U.S. veterinary schools. Of the dogs studied, 15,000 had lymphoma, and prevalence was compared between intact males, intact females, castrated males and spayed females, Henry said. She added that roughly half of all dogs that live to the age of 10 will develop some type of cancer. For humans, cancer is the second leading cause of death in the United States, she said.

“The fact that it was the intact females at reduced risk suggests that there is a link to intact reproductive status that explains this rather than something unique just to [the] female gender,” Henry added.