If you’re searching for a reason not to have sex with animals, add this to the list: It could give you penis cancer, according to a new study published in the Journal of Sexual Medicine.

The authors found that men who have had sex with animals were twice as likely to develop penile cancer as those who stick with their own kind.

Lead author Stenio de Cassio Zequi, a urologist in Sao Paulo, gave Live Science his theory explaining the increased risk.

“We think that the intense and long-term SWA [sex with animals] practice could produce micro-traumas in the human penile tissue,” Zequi said. “The genital mucus membranes of animals could have different characteristics from human genitalia, and the animals’ secretions are probably different from human fluids. Perhaps animal tissues are less soft than ours, and non-human secretions would be toxic for us.”

A female member of Equality For All, a pro-zoophilia group, told The Huffington Post that the results of the study should prompt people to take precautions, like using a condom, when having sex with animals, but she said it likely would not deter diehard zoophiles.

“Expecting people who truly love animals to give up their sexuality and nature just because of some physical dangers would be as absurd as expecting gays to become straight because of AIDS,” Sallie Graves wrote in an email.

“They might become more cautious … but they wouldn’t change their nature. A true zoophile can’t change their attraction and love just because of a higher or lower infection risk.”

Graves also emphasized that E.F.A. sees inter-species sex as benign. They also say they are against causing physical pain to animals.

Graves does not endorse harming animals, and believes those who insist sex with animals is inherently abusive are wrong.

“How in the world can I be abusing my dog if I get on my hands and knees and he licks and humps me without me even having to ask for it?” Graves wrote.

Zequi’s study is based on a questionnaire about personal and sexual habits completed by 118 penile cancer patients and 374 healthy men recruited between 2009 and 2010.

Additionally, the research found that people who said they have had sex with animals also reported more venereal diseases.

Source: Huffington Post