should we be de-sexing our dogs?

In North America, spaying and neutering are generally regarded as a necessary and responsible approach to controlling populations of stray and homeless dogs. But new research indicates that de-sexing our dogs can negatively impact their health. So what’s the solution?

In the US and Canada, dogs are routinely spayed and neutered when they’re between four and nine months old. Many puppies coming out of shelters are spayed as early as eight weeks of age. In order to be considered a responsible owner of a female dog, you’re expected to spay her before her first estrus cycle. However, recent studies have found that de-sexing dogs, especially too early in life, can have a detrimental effect on their health.

What many of us in North America don’t realize is that intact dogs are the norm in Europe. Responsible dog owners are those who effectively manage their intact dogs to prevent them from reproducing. When female dogs go into heat, people simply manage the situation by removing them from group events until the heat cycle is complete. The dogs are kept at home or sequestered from males, and are walked on a leash. Alternatively, their guardians implement ways to prevent unwanted pregnancies (more on this later).

Why is spaying and neutering an issue?

The problem with de-sexing dogs is that we’re not just sterilizing them; we’re also removing extremely important sex hormone-secreting tissues, namely the ovaries and testes. As a result, we’ve created health problems that are non-existent or significantly less prevalent in intact pets.

Over the last several years, a number of small, breed-focused and primarily retrospective studies have been conducted on the effects of spay/neuter in large and giant breeds, providing us with a growing body of evidence that indicates de-sexing, especially early in life, significantly increases the risk of serious health problems.

In large and giant breed females, for example, spaying increases the risk of obesity, cranial cruciate ligament disease, hip dysplasia, urinary incontinence, cystitis, and several types of cancer (see below), including lymphoma, mast cell tumors, hemangiosarcoma and osteosarcoma.

Musculoskeletal disorders in de-sexed dogs

Removing a dog’s ability to produce important hormones while his/her skeleton is still developing can result in delayed closure of the growth plates at the end of each long bone. This can cause a dog’s legs to grow longer than normal.

  • One study indicates that Labrador and golden retrievers de-sexed before six months of age develop one or more joint disorders at two to five times the rate of intact dogs.
  • When it comes to problems with cranial cruciate ligaments, large breed dogs spayed under six months of age have three times the risk for early life CCL injuries, while dogs de-sexed at any age have a two to three times higher incidence of CCL disease compared with intact dogs.
  • In a study of several hundred golden retrievers, none of the intact dogs had CCL disease; however, 7.7% of spayed females who were de-sexed before they were a year old developed CCL injuries.
  • Another study of 40 years of data collected on a range of different dogs de-sexed at a variety of ages showed a 17% increased risk of hip dysplasia.

How I approach the sterilization issue

Over the years, I’ve changed my views on de-sexing, based not only on a mounting body of research, but also on the health challenges faced by so many of my canine patients after I sterilized them. My current approach is to work with each individual pet owner to make decisions that will provide the most health benefits for the dog.

1. Whenever possible, I prefer to leave dogs intact. However, this approach requires a highly responsible pet guardian who is fully committed to and capable of preventing the dog from mating (unless the owner is a responsible breeder and that’s the goal).

It’s important to note that I’m not advocating the adoption of intact shelter animals to people who may or may not be responsible pet owners. Shelter veterinarians don’t have the time or resources to build a relationship with every adoptive family, so the animals in their care must be sterilized prior to adoption to prevent more litters of unwanted pups.

2. My second choice is to sterilize without de-sexing. This means performing a procedure that will prevent pregnancy while sparing the testes or ovaries so they can continue to produce the hormones essential for the dog’s health and well-being.

For females, this involves either a tubal ligation or a modified spay (basically a hysterectomy). The modified spay removes the uterus while preserving the hormone-producing ovaries. It also eliminates the possibility of pyometra because the uterus is removed.

Unfortunately, veterinary schools in the US only teach full spays and neuters, so unless your vet has obtained additional training in sterilization techniques that spare the ovaries or testicles (which is unlikely), you’ll have only one option available. The Parsemus Foundation maintains a list of vets that perform ovary-sparing spays and also has instructional videos for vets who want to learn the technique.

In this case, my suggestion would be to wait until your dog has reached full musculoskeletal maturity; and if you have a female, I’d wait until she has completed her first estrus cycle before scheduling the surgery.

Cancers linked to de-sexing

  • Research shows that intact large and giant breed dogs have a lower risk of developing lymphoma than de-sexed dogs. Another risk factor for lymphoma is de-sexing before the age of one. Spaying/neutering is also associated with a two to four times higher risk for mast cell tumors.
  • In another study, Rottweilers who were de-sexed before they were a year old had a one-in-four lifetime risk for bone cancer; and in general, they were significantly more likely to develop the disease than intact Rotties.
  • A further study concluded that from 1980 through 1994, the risk for bone cancer in large breed purebred dogs increased twofold in dogs that were de-sexed. Spayed or neutered dogs are also three times more likely to develop transitional cell carcinoma of the bladder than intact dogs.
  • A number of studies have also linked behavior problems to early de-sexing.

Responsible care of an intact female dog

Intact female dogs have one or two heats a year. You can typically tell a heat cycle is on its way when the dog’s vulva begins to enlarge. As with humans, there’s bleeding involved; but unlike human females, who are not fertile during menstruation, dogs are just the opposite. Female dogs can get pregnant only during heats, and for about three to four days as unfertilized eggs ripen in their bodies.

Some dogs will signal during this time by flagging, which means lifting the tail base up and to the side. Some females will stand and can be mounted at any time during their heat cycle, including before and after they’re pregnant or fertile. Others show no behavior signs whatsoever. Owners of intact female dogs must know the signs of heat in their own pets, so they can separate them from male dogs during this time. If you have a female dog in heat, you should never leave her alone outside, even for a second, and even in a fenced-in yard.

Another way to prevent unwanted pregnancies is to use a product such as the Delay Her Spay harness from PABS. This “chastity belt” for dogs deters accidental breeding. Made from soft and durable webbing with a mesh backing, it’s designed to keep the dog’s hind end covered at all times, while allowing her to urinate through the mesh, and defecate over the top.

The heat cycle lasts about three weeks, but the menstrual bleeding can be unpredictable during this time. It isn’t consistently heavy nor does it occur every day all day. Many people with intact female dogs invest in special diapers or panties that can hold a sanitary napkin to contain the discharge. Pads can also be added to the Delay Her Spay harness to protect your floors and furniture from discharge. Typically, though, female dogs are incredibly good at keeping themselves very clean. Most of the time, there’s very little mess.

Keeping your dog intact, or at least delaying the spay/neuter procedure, can help prevent a host of health problems down the road. Having an intact dog comes with some extra responsibilities, of course, but they’re not onerous and are well worth the effort.


Veterinarian Dr. Karen Shaw Becker received her degree from the Iowa State College of Veterinary Medicine. She owns/operates Natural Pet Animal Hospital, Feathers Bird Clinic, TheraPaw Rehabilitation and Pain Management Clinic and Covenant Wildlife Rehabilitation in Illinois. She co-authored Real Food for Healthy Pets and hosts a holistic animal wellness website (