By Dr. Becker
In the U.S., dogs are routinely spayed or neutered when they’re between 4 and 9 months old. In the words of Dr. Clara Goh, surgical oncologist at Colorado State University’s Veterinary Teaching Hospital, writing for Clinician’s Brief:
“The decision to perform this procedure is often based on convention, habit or misconception of health benefits rather than on an evidence-based assessment of each patient.”1
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 breed dogs, including the Rottweiler and Golden Retriever.
Goh provides the following information to illustrate what the research has uncovered about the potential benefits and adverse effects of gonadectomy:
|Condition||Effect of Spay on Female Large/Giant Breeds||Effect of Neuter on Male Large/Giant Breeds|
|Overall longevity||Mild increase||Mild increase|
|Obesity||Moderate increase||Moderate increase|
|Cranial cruciate ligament disease||Moderate increase*||Moderate increase*|
|Hip dysplasia||Mild increase*||Mild increase*|
|Mammary tumors||Marked decrease*||—|
|Uterine, ovarian and vaginal tumors||Prevents||—|
|Perianal gland tumors||—||Market decrease|
|Lymphoma||Mild increase||Mild increase*|
|Mast cell tumors||Mild increase||—|
|Hemangiosarcoma||Mild increase*||Mild increase|
|Osteosarcoma||Mild increase*||Mild increase*|
|Transitional cell carcinoma||Mild increase||Mild increase|
|Urinary sphincter mechanism incompetence||Moderate increase*||—|
|Benign prostatic hyperplasia||—||Marked decrease|
|Perineal hernia||—||Moderate decrease|
*Age at time of surgery may be important
To summarize the information in Goh’s table, spaying or neutering large and giant breed dogs decreases or prevents most reproductive organ disease, as you would expect, since conventional desexing surgery removes some or all of those organs and the hormones they produce.
The diseases for which spayed or neutered dogs are at increased risk are, as you also might expect, some of the most common disorders seen in dogs today. They include obesity, cranial cruciate ligament (CCL) ruptures, hip dysplasia, several types of cancer, urine dribbling (incontinence) and cystitis (bladder inflammation).
Musculoskeletal Disorders in Desexed Large and Giant Breed Dogs
As Goh points out, removing a dog’s ability to produce important hormones while his 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, as you can see in this example of two adult male Golden Retrievers. The big guy on the left is intact, with normal conformation for the breed. The leggier guy on the right was neutered at 5 months and has a quite noticeable longer-limbed conformation.
Sadly, even though the taller Golden on the right is certainly as handsome and fit-looking as the dog on the left, his longer limbs may put him a higher risk for orthopedic disease.
Labrador and Golden Retrievers neutered before 6 months of age develop one or more joint disorders at two to five times the rate of intact dogs.2
When it comes to problems with cranial cruciate ligaments, large breed dogs spayed or neutered at under 6 months of age have three times the risk for early life CCL injuries.3 Dogs desexed at any age have a two to three times higher incidence of CCL disease compared with intact dogs.4,5
In a study of several hundred Golden Retrievers, none of the intact dogs had CCL disease; however, 5 percent of neutered males and 7.7 percent of spayed females who were desexed before they were a year old developed CCL injuries.6
The body condition score was the same for all the dogs, which indicates that changes in the build of the desexed dogs was to blame.
Male Golden Retrievers neutered at under 1 year developed hip dysplasia at double the rate of intact males, and the disease also appeared earlier in the desexed dogs.7 Another study of 40 years of data collected on a range of different dogs desexed at a variety of ages showed a 17 percent increased risk of hip dysplasia.8
Cancers Linked to Desexing of Large and Giant Breeds
Studies have shown that intact large and giant breed dogs have lower risk for developing lymphoma than spayed or neutered dogs. Another risk factor for lymphoma is desexing before the age of 1.9 Spaying/neutering is also associated with a two to four times greater risk for mast cell tumors.10
In a study of Rottweilers, both males and females who were desexed before they were a year old had a 1-in-4 lifetime risk for bone cancer, and in general, spayed or neutered dogs were significantly more likely to develop the disease than intact Rotties.11
Another study concluded that for the period 1980 through 1994, the risk for bone cancer in large breed, purebred dogs increased twofold for dogs that were spayed or neutered.12 Desexed dogs also have a three times greater risk of developing transitional cell carcinoma of the bladder than intact dogs.13,14
Food for Thought If You’re Considering Spaying or Neutering Your Large or Giant Breed Dog
Over the years I've changed my view on spaying and neutering dogs, based not just on a mounting body of research, but also on the health challenges faced by so many of my canine patients after I desexed them. That’s why my current approach is to work with each individual pet owner to make decisions that will provide the most health benefits for the dog.
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 pets.
My second choice is to sterilize without desexing. This means performing a procedure that will prevent pregnancy while sparing the testes or ovaries so they can continue to produce hormones essential for the dog's health and well-being.
This typically involves a vasectomy for male dogs, and either a tubal ligation or modified spay for females. The modified spay removes the uterus while preserving the hormone-producing ovaries. It also eliminates the possibility of pyometra because the uterus is removed.
Rarely, older, intact male dogs develop moderate to severe benign prostatic hyperplasia (an enlarged prostate) that may be improved with conventional neutering. Generally speaking, mature intact dogs have had the benefit of a lifetime of sex hormone production, so the endocrine imbalances we see with spayed or neutered puppies don't occur when dogs are desexed in their later years.
Unfortunately, veterinary schools in the U.S. only teach full spays and neuters, so unless your own vet has obtained additional training in sterilization techniques that spare the ovaries or testicles (which is unlikely), you’ll have only one option available to sterilize your pet.
In that case, my suggestion would be to wait until your dog has reached full musculoskeletal maturity, and if you have a female, I’d also wait until she’s completed her first estrus cycle before scheduling the surgery.