“Should I Spay my Dog?” is one of the more common questions veterinarians get. This article is a veterinarian’s review of the pros and cons of spaying a female dog. It is backed by science so you can make an informed decision.
Spaying female dogs is widely advocated by rescue organizations and veterinarians in order to reduce the population of unwanted dogs, but is it right for your dog?
Spay refers to the surgical procedure of removing the reproductive organs of a female dog, which is also known as ovariohysterectomy. This procedure has been a common practice for many years and is primarily performed to prevent unwanted heat cycles and litters of puppies.
This article breaks down the potential benefits and negatives of spaying a dog, with references to support the claims so that you can make an informed decision. You will find that this article goes into the science so does get a little technical, but I believe you deserve to know the complete story before you decide. If you don’t want to go into detail skip ahead to the conclusion and my recommendations.
If you are trying to decide if you should breed your dog, please check out an article I wrote on choosing the best Golden Retriever Breeder. Although this is specific to Golden Retrievers, it does show the huge amount of work and testing required to be an ethical breeder. This does not include the health risks of breeding to the dog. Decide if you are able to commit to breeding responsibly, then return here if you deciding breeding is not the best choice. If you have already decided that spay is the right thing to do for your puppy check out my article on When should I spay my Dog (pending)?
Benefits of Spaying a Dog
Beyond the benefits of controlling the population of stray dogs, spaying your female dog can reduce the risk of certain serious health problems, and improve her overall quality of life. In this section we lay out the details of the benefits of spaying a dog.
Spaying female dogs prevents unwanted puppies
One of the primary benefits of spaying a dog is the reduction of unwanted breeding. Unwanted breeding leads to a significant number of homeless and abandoned dogs, which puts a strain on animal shelters and rescues. In the USA 1-2 million dogs are euthanized every year in shelters across the country. By spaying a female dog, pet owners can prevent accidental breeding and contribute to reducing the number of homeless animals.
You should not underestimate the natural drive to mate that dogs have. We veterinarians love to tell stories of the crazy way puppies came to be. One of my favorite stories is the dogs that bred through a chain link fence with the male on the outside and the female on the inside. Yes, it really happened, there were puppies as proof.
In addition if your dog does become accidentally pregnant, there are many risks associated with carrying, delivering and nursing puppies. Some of these risks such as dystocia (trouble giving birth) and pyometra (uterine infections) are life-threatening. These can all be avoided with spay.
Increased Lifespan of Spayed Dogs
Spayed dogs live longer.
A very large study by University of Georgia and another study by Banfield Pet Hospitals both found that spayed female dogs lived longer than intact (un-spayed) female dogs. The UGA study said they lived 26.3% longer and the Banfield study found spayed dogs lived 23% longer. Although the specific reasons for living longer are not clear, there is evidence in these studies that spayed dogs live 1-2 years longer than dogs that are not spayed.
Spaying a Dog Reduces the Risk of Some Health problems
Spaying a dog can also reduce the risk of certain health problems (but increases others, see the negatives below). Female dogs that are not spayed are at a higher risk of developing certain types of cancers, such as mammary cancer and ovarian cancer. They are also at risk of uterine infections (pyometra).
In my mind, the large reduction in risk for mammary cancer and pyometra are the most important benefits of spaying. These are serious, life-threatening diseases that are fairly common in intact dogs. This is the reason I choose to spay my own dogs.
Spaying a Dog Reduces The Risk of Specific Types of Cancer
Mammary (breast) tumor is the most common tumor of female dogs. About 3.4% of female dogs will get mammary tumors in their lifetime but since most dogs are spayed this does not really help with the spay decision. What we really need to know is: what is the increase in risk for intact females versus spayed females?
Intact (un-spayed) female dogs are 7 times more likely to get mammary tumors. In a lifetime study of intact female beagle dogs, 70.8% developed at least one mammary tumor. In another study of dogs in Norway 53% of the population of mostly intact dogs (spaying is rare in Norway) got mammary tumors.
In contrast, a landmark study of mammary tumors showed that 0.05% of female dogs spayed before their first heat got mammary tumors. 8% of female dogs got tumors if they had 1 heat cycle and 26% if they had two heat cycles before spaying. After that, incidence of tumors was about the same, although other studies showed their was still benefit of spaying later.
This is a serious concern because mammary tumors in dogs have a about a 50% chance to be malignant cancer. Although mammary cancer can often be treated if caught early, this should be major factor in your decision. Prevention is the best medicine.
In addition, if the dog does not have a uterus or ovaries, she cannot get ovarian cancer or uterine cancers. These are rare in female dogs and can be cured with spay in most cases, but again not getting them at all is still better.
Spaying virtually eliminates the chance of Pyometra (Uterine infections)
In addition, spaying a dog can also help to prevent pyometra, which is a serious bacterial infection of the uterus that can quickly become life-threatening if left untreated. Repeated heat cycles set the uterus up for infection. In older intact female who have had many heat cycles this is not uncommon. It is a rapidly progressive disease and is very hard for the owner to notice the infection until it is too late. As a reproductive specialist, I have seen many of these cases in breeding dogs, sadly not all of them survived despite my best efforts.
Spay surgery removes 99% of the uterus and stops heat cycles, so it almost completely prevents the disease.
Spaying eliminates the mess from heat cycles
A “heat” is the time in a female dog’s reproductive cycle when they can get pregnant.
Some people call it a “period” because they have a bloody discharge during this time. It is actually totally different than a human period. It does, however, make a huge mess. Blood spots on the floor, your bed, and the couch are not fun to clean up.
Although they do make diapers for dogs to wear during this time, I know many female dogs who will not keep them on. My dog during her one and only heat cycle, repeatedly took off her diaper and started eating the bloody part out. Seriously gross and veterinarians deal with gross for a living.
The constant licking of their private parts to try to keep clean during this time can also drive an owner crazy. This is I think the second most important reason my female dogs are spayed.
Spaying your dog can prevent some behavioral problems
Another benefit of spaying a dog is the prevention of behavioral problems that are associated with hormones. Hormones, especially testosterone (yes females have that too) can increase some undesirable behaviors.
Female dogs that are not spayed are more likely to display issues such as territorial aggression, marking behaviors, and restlessness during heat cycles. Spaying a dog greatly reduces hormone levels and can help to reduce or eliminate these behavioral problems and improve the overall quality of life for the dog.
Behaviors that are unrelated to hormones are not affected by spay. For example, studies found that working dogs (scent dogs, police dogs, etc.) are not harder or easier to train when spayed.
Spay Reduces visits from stray males
Intact male dogs can smell a female dog in heat from sometimes miles away. Male dogs will sometimes go to extradentary lengths to get to a female in heat. Spaying prevents heat cycles and therefore eliminates unwanted male visitors because of the heat.
Negatives of Spaying a Dog
While spaying has traditionally been viewed as a positive step in preventing unwanted breeding and reducing the risk of certain health problems, it is important to consider the potential negative effects of this procedure.
In some European countries spaying a female dog is not common. In fact in Norway it is illegal as it is considered mutilation. It is interesting to note that stray dogs in Norway are virtually non-existent. So it is possible to manage the pet population without spaying, it just has not been achieved in the USA.
Spay surgery does have risk
One negative of spaying is the risk of complications during the surgical procedure. In addition, spaying is a more complicated procedure than neutering. There are higher risks to spay than with neutering a male dog. A spay removes the uterus and ovaries and is therefore an open abdominal surgery. In humans it is considered major surgery. In any major surgery, there is a higher risk of complications.
As with any surgery, there is a risk of bleeding, infection, and adverse reactions to anesthesia. According to Dr. Root Kustritz in an academic paper written in 2007, the incidence of surgical complications in dogs undergoing spay surgery was approximately 17%. Most of these were minor such as minor bleeding and minor infections but some were more serious.
The chances of major complications are low, however, in a study by Dr. Pollari in 1996 it was reported that out of just over 1000 dogs, 1 dog died and 6 had major complications.
Complications of spay surgery are more common (but still rare) when a dog over 2 years of age is spayed than when they are spayed younger. So you should consider your dogs age when making the decision. See my article on When to Spay.
Long Term Health Consequences of Spay
Spaying removes the source of a dog’s hormones, which leads to changes in the levels of estrogen, testosterone, and progesterone. These changes can lead to the development of certain health problems, such as an increased risk of obesity, urinary incontinence, and joint problems. These health problems can have a significant impact on the dog’s quality of life and can be costly to treat.
Spayed Dogs are More Likely to Develop Obesity
The changes in hormones increase the potential for obesity.
Extra body fat can have serious health implications. According to a Report by Banfield Pet Hopsital, over 51% of dogs in the US are overweight. The most common risk factor for obesity found in many studies is being spayed or neutered. This means that the risk of being obese is greatly increased in spayed female dogs.
One large lifetime study of Labrador found that moderate obesity can decrease life expectancy by almost two years compared to lean Labradors.
Obese dogs are much more likely to develop painful joint problems during their lifetime. Obese young adults are more likely to develop hip dysplasia. Obese dogs often develop arthritis earlier and have more severe arthritis than lean dogs. Arthritis is a condition where there is inflammation in the joints cause pain and stiffness.
The most important take away here is that spay is only a risk factor for a disease that can be prevented with proper diet and exercise routines. In my opinion, if you are confident you can control these things, obesity risk should not be a factor in your decision to spay or not.
However, be realistic in when you decide if you are able to control your dog’s diet. For example, if you have very young children who constantly drop food or if the rest of your family will not comply with proper diet recommendations (limited table food and snacks). Also, if your family has a history of having overweight dogs, think carefully about if you will be able to prevent it for your new puppy.
Urinary Tract Infections
Studies have consistently found an increased risk of urinary tract infections (UTIs) in spayed female dogs. No clear reason for this has been found. UTIs in dogs are common but easily treated in most uncomplicated cases so should not be a major part of a decision not to spay your dog.
Urinary incontinence is the involuntary leakage of urine. It has many potential causes but spayed female dogs are more likely to get the disease. In a recent study (O’Neil 2021), dogs that were spayed or neutered were 1.9 times more likely to develop incontinence than intact dogs.
Studies indicate that between 5 and 20% of spayed female dogs may develop what we call hormone responsive urinary incontinence. Meaning if we give estrogen the problem gets better. However, estrogen treatment has its own risks making that treatment undesirable. These dogs often leak urine when they are sleeping or resting.
Spaying a Dog may increase Joint problems
In one large study of Golden retrievers by Dr. Torres de la Riva in 2013, the chance of a cranial cruciate ligament injury was significantly increased if a dog was spayed early (before 1 year old) vs. spayed late or left intact. This injury is the same knee injury as an ACL injury that human athletes often get. It should be noted that this was a study of only one breed of dog and may not be true of small breed dogs, or of dogs of unrelated breeds.
However, cruciate ligament rupture is very common in large and giant breed dogs. It is very costly to repair and can result in arthritis and pain in the joints as the dog gets older.
Negative changes in behavior and personality
Some studies have shown that spaying can lead to changes in behavior, likely due to decreases in estrogen and another hormone called oxytocin. Increased aggression toward humans with unfamiliar dogs and toward family members. Increased separation anxiety may also have the same cause. Decreased energy and activity (lethargy) compared to intact dogs has been observed and may be a cause of increase obesity in spayed females. In some cases, these changes can be significant and lead to decreased quality of life for the dog.
Increased Age Related behavioral problems
In male dogs a study showed that is more age-related mental health decline in neutered males than in intact males. However, the same study has not been completed for female dogs.
Increase in Some Less Common Cancers
There may be an increase in Lymphosarcoma, Osteosarcoma, and Hemangiosarcoma in spayed females versus intact females. Studies disagree on if these differences are real so use caution when factoring this into your decision.
These are also more uncommon cancers for most breeds. Osteosarcoma and Hemangiosarcoma occurs in about 0.2% of dogs each. Lymphosarcoma (also called lymphoma) occurs about half as often. All of these are much less common than mammary tumors. However, if you have a breed that is predisposed to one of these types of cancer, like Golden Retrievers, it might factor into your decision.
For those with Golden Retriever Puppies, I have written an article on Spaying that is specific to Golden Retrievers.
Will Spay affect your relationship with your dog
Finally, spaying can also have an impact on the pet owner’s relationship with the dog.
Some pet owners report feeling a sense of loss after their dog has been spayed, as the procedure marks the end of the dog’s reproductive potential. This can lead to changes in the way the pet owner views and interacts with the dog.
On the other hand spaying your dog may make life easier for the owner. Heat cycles may be annoying and messy, no longer having to deal with that can increase the bond between dog and owner.
Take your own feelings and emotions into account when deciding if you should spay your dog.
Final Conclusions and Recommendations on Spaying a Dog
In conclusion, spaying a female dog offers a range of benefits, including reduction of unwanted breeding, reduction of the risk of certain health problems, improvement of behavioral problems, and a positive impact on the pet owner’s life. While spaying has traditionally been viewed as a positive step for female dogs, it is important to consider the potential negatives of this procedure.
Pet owners who are considering spaying their dogs should consult with a veterinarian to determine the best course of action for their specific situation.
In my opinion, the benefits associated with reduction in common serious diseases (mammary tumors) outweigh the less common or preventable diseases that are increased in spayed dogs. For dogs whose owners have good control, I recommend spaying female dogs after their first heat cycle. In shelter situations, or when owners are not certain of their ability to contain their dog, early spay may be the best option.
For more information on the best timing of spay please read my article on When to Spay a Dog (pending).
Belknap, D., & Olvera, N. (2011). Ovariohysterectomy in dogs: A review of the literature. Journal of the American Animal Hospital Association, 47(5), 284-294.
Root Kustritz, M. V. (2007). Determining the optimal age for gonadectomy of dogs and cats. Journal of the American Veterinary Medical Association, 231(11), 1665-1675.
Johnson, L. (2002). Spaying or neutering dogs and cats: Understanding the procedure and its implications. Journal of the American Veterinary Medical Association, 220(7), 969-973.
Verstegen, J., Hart, B. L., & message, D. (2003). The role of gonadal hormones in canine aggression. Applied Animal Behaviour Science, 82(1), 59-70.
Salzberg, M. J. (2001). Advantages and disadvantages of spaying dogs and cats. Journal of the American Veterinary Medical Association, 218(6), 791-794.
Van der Borg, M. A., De Roos, P. R., & Hazewinkel, H. A. (2004). Effects of ovariohysterectomy on behaviour in bitches. The Veterinary Journal, 168(2), 123-131.
O’Farrell V., Peachey E. (1990). Behavioural effects of ovariohysterectomy on hitches. Journal of Small Animal Practice, 31(12), 595-598
Jessica M. Hoffman, Kate E. Creevy, Daniel E. L. Promislow. Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs. PLoS ONE, 2013; 8 (4): e61082 DOI: 10.1371/journal.pone.0061082
Pollari FL, Bonnett BN & Bamsey SC, et al. Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records. J Am Vet Med Assoc 1996;208:1882–1886.
Burrow R, Batchelor D, Cripps P. Complications observed during and after ovariohysterectomy of 142 bitches at a veterinary teaching hospital. Vet Rec 2005;157:829–833.
Lund, E.M., Armstrong, P.J., Kirk, C.A., & Klausner, J.S. (2005). Prevalence and risk factors for obesity in adult dogs from private US veterinary practices. International Journal of Applied Research in Veterinary Medicine, 3(2), 88-96.
Torres de la Riva, G., Hart, B.L., Farver, T.B., Oberbauer, A.M., Messam, L.L.M., & Willits, N. (2013). Neutering dogs: Effects on joint disorders and cancers in golden retrievers. PLoS ONE, 8(2), e55937. doi:10.1371/journal.pone.0055937
Kealy, R.D., Lawler, D.F., Ballam, J.M., Mantz, S.L., Biery, D.N., Greeley. E.H., & Stowe, H.D. (2002). Effects of diet restriction on life span and age-related changes in dogs. Journal of the American Veterinary Medical Association, 220, 1315-1320.
Banfield Pet Hospital. Veterinary Emerging Topics Report on Overweight Pets. (2020) https://www.banfieldexchange.com/-/media/Project/Banfield/Main/en/Exchange/Vet-report-overview/PDF/2020VETReportOverweightPetsUpdated.pdf?rev=13866c9cc62b47daa8460675e2527c4f&hash=5223B513C36A121472ED173735612A1D
O’Neill DG, James H, Brodbelt DC, Church DB, Pegram C. (2021) Prevalence of commonly diagnosed disorders in UK dogs under primary veterinary care: results and applications. BMC Vet Res. 2021 Feb 17;17(1):69. doi: 10.1186/s12917-021-02775-3.
Benjamin S.A., Lee A.C., Saunders W.J. (1999) Classification and behavior of canine mammary epithelial neoplasms based on life-span observations in beagles. Veterinary pathology 36:423-436.
Zandvliet M. Canine lymphoma: a review. Vet Q. 2016 Jun;36(2):76-104. doi: 10.1080/01652176.2016.1152633. Epub 2016 Mar 8. PMID: 26953614.
C. Pittaway, I. Schofield, J. Dobson, D. G. O’Neill, D. C. Brodbelt. 2019. Incidence and risk factors for the diagnosis of lymphoma in dogs in UK primary-care practice. 60:10, 581-588. https://doi.org/10.1111/jsap.13054