https://getpocket.com/explore/item/the-growing-debate-over-spaying-and-neutering-dogsby Karen Brulliard
October 11, 2019
“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.
But the common wisdom has been complicated in recent years amid widening evidence connecting spaying and neutering to health problems in dogs. The findings are stronger for certain breeds and large dogs, and age of neutering plays a role. But the research is causing some owners and veterinarians to question the long-held tenet that fixing puppies — or fixing, period — is a necessary part of responsible pet ownership.
(excerpt)