Spaying and neutering dogs: myth vs reality


At the AVMA Convention in Austin, Texas, a veterinarian discusses when—and if—a dog should be sterilized

Medical cone used for spay and neuter

Photo: Kristi/Adobe Stock

“Every lame animal that comes to your practice is not treated the exact same way; every animal hit by a car is not treated the same. I am going to try and convince you that spaying and neutering are no different in that respect: you should be taking each case and evaluating it separately.

There is simply no cookie cutter answer to spaying and neutering dogs.” So began Bruce W Christensen, DVM, MS, DACT, founder of the Kokopelli Assisted Reproductive Services in Sacramento, California, in his session, “To spay or not to spay? And how? And when?” at the 2024 American Veterinary Medical Association (AVMA) Convention in Austin, Texas.1

Christensen broke down the reasons for canine sterilization into 3 main categories: To prevent the contribution to the stray pet population; to halt undesirable behaviors; and to decrease the chance of contracting disease.

For the first case, overpopulation, although Christensen acknowledges the problem exists, he said, “keep in mind, there is also a variety of places people get their dogs from (ie, animal shelters, friend, breeder, etc.). “That should be considered when you are looking at the spaying or neutering,” Christensen said. If, for example, the dog comes from a reputable breeder, that’s different than if the dog is coming from a shelter, which usually requires the dog is spayed or neutered before leaving the shelter. When coming from a breeder, said Christensen, almost always there is a discussion about spaying or neutering this animal. For breeders who, for example, sell a puppy that they consider great for future breeding, they might want to retain some coownership or breeding rights, with sterilization happening later in life for that dog. For other breeders, it might be in the contract that the adoptive family will spay or neuter this puppy at a certain point. “You, as the veterinarian, should be aware that these conversations are happening, and if you are not on board with these decisions, then you should ask yourself why,” Christensen said.

Secondly, Christensen addressed unwanted behaviors. He noted that actions such as [male] aggression, mounting, and urine marking, veterinarians are taught, will be reduced or eliminated with neutering. But Christensen invited his audience to “step back and look at the practice that you have, and ask yourself, ‘are the aggressive animals predominantly intact males, or are there plenty of spayed and neutered dogs that also have aggressive issues?’ The idea that neutering is going to fix this is not true.” Christensen pointed to his own practice, where most of his dogs are intact a good portion of their lives, with owners who are “highly hands-on with their animals,” so consequently, the majority of these dogs are well-behaved, italicizing that behavior is largely a result of “how the dog is handled and trained, from neonate to adulthood.”

Next, Christensen tackled the subject of disease prevention, running through several studies that looked at various diseases impacted by sterilization. Common medical conditions that are increased by sterilization of dogs include hemangiosarcoma (females), osteosarcoma (males, if done before age 1 year), lymphoma (females), and cranial cruciate disorders. On the other hand, if a female dog is spayed, there is a “zero chance” of contracting pyometra, and her chances are greatly lessened that she will develop mammary tumors. Additionally, if a male dog is neutered, there is a 0% chance he will get benign prostatic hyperplasia (BPH). However, Christensen added, “BPH is medically treatable, inexpensive, and without side effects, and “in my opinion to keep a dog from getting BPH is not a good reason, in and of itself, to neuter him. What these studies lacked, noted Christensen, “Was information on breed, gender, and age of neutering; assumed impact on behavior; and overall hormonal effects.”

Having these conversations with dog owners before deciding to spay or neuter a dog, emphasized Christensen, “Are crucial, for the betterment of the health of the dog.”


Christensen BW. To spay or not to spay? And how? And when? Presented at: American Veterinary Medical Association Convention; Austin, TX: June 21-25, 2024.

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