Originally written by Karin Brulliard for The Washington Post

Beneath the fluffy backsides of Valerie Robson’s two male golden retrievers is an unusual sight: intact anatomy. Neither dog is neutered.

This presents occasional challenges. Astro and Rumble are barred from most doggy day-cares, and many boarding kennels won’t take them. But although Robson has no intention of breeding the dogs, she says she has no regrets. Research that suggests neutering could be linked to cancers and joint disorders persuaded her that skipping sterilization was best for her pets.

“Sometimes people notice,” said Robson, a county government employee in Conifer, Colo. “I just explain that we chose to do this for health and wellness, and he’s a good boy, and it’s never been an issue.”

“Intact” dogs were the norm for a long time, and a litter of puppies was often part of the deal. But in the 1970s, when overflowing animal shelters were euthanizing millions of homeless dogs annually, spaying and neutering puppies — procedures that involve removing ovaries or testicles — became the dogma in the United States.

It still is: Surveys indicate a large majority of pet dogs are fixed, and 31 states and the District require that pets adopted from shelters or rescues be sterilized. The surgeries simplify pet ownership by preventing females from going into heat and, some believe, by improving dog behavior, though experts say that is not clearly supported by research.