Should You Spay Your Dog and When? (risks vs benefits)

The traditional , dogmatic view that all bitches should be spayed at around 6 months of age has more recently been challenge as more studies look into the risks and benefits of our female dogs undergoing this operation.  Rather than make the decision easier though, the choice has become more confused.  It is not as black and white as some would have you believe.

So then, when should you spay your dog and should you spay them at all?


If you just want my recommendations then I feel that the benefits of being spayed certainly outweigh the potential drawbacks and so all female dogs who are not going to be used for breeding should be spayed.

For small breed dogs I would still recommend spaying at around 6 months old before their first season.  For larger breed dogs however, where there is no risk of them becoming pregnant and where they can be successfully managed while on heat, I recommend delaying this operation until they reach 1 year of age or a little older.

Is this the right decision for you?  Well, here are the potential benefits and drawback of being spayed which you can discuss with your veterinarian to reach a decision you are completely comfortable with.


Reducing mammary cancer risk

Lets jump into the benefits of spaying with the first benefit being a reduction in mammary cancer.  It is generally well accepted that the earlier a bitch is spayed, the lower it's chance is of getting mammary cancer.  It is said that if spayed before their first season a dogs chance of getting this disease is reduced by around 99.5%.  If spayed before their second season the risk still falls by about 94% and if before their third season by a respectable 75%.

After this there may not be much benefit although for those dogs that do develop mammary cancer, if they are spayed either at the time of cancer removal or were spayed up to 2 years before the cancer developed then they are expected to live longer.

Now although these are well recognized points there are only a few studies that have looked into this and so the evidence may not be as strong as it is generally felt to be.  Having said that I can't remember the last time I saw a female dog with mammary tumors that had been spayed when young.

It's all well and good reducing the risk of a disease but this only becomes relevant to a decision if we know how common and how serious the condition is.  Well, by the age of 8 years, 6% of dogs will have mammary masses and this increases to 13% at 10 years of age.  This will only increase as they age further.  Of these, half will develop malignant cancers and 60% of those will die as a result of their cancer.  That's 1 in 12 entire female dogs dying of mammary cancer they develop by the age of 10.

This is a significant disease that is significantly reduced by spaying, ideally at some point before the 3rd season, preferably before an individuals first season.

Prevent pyometra

Our next disease to discuss is pyometra.  If you want a complete run down of this disease then here is a complete discussion about pyometra and its treatment.  For now lets just say that this is a life-threatening condition that affects 1 in 4 entire females by the age of 10 and generally requires emergency surgery to cure.  Even with treatment 5% of dogs will die and without treatment death is an almost certainty.

Spaying a bitch at any age will virtually eliminate the risk of pyometra.  Another very significant disease prevented by spaying.

With around 38% of entire female dogs suffering from either pyometra or mammary masses, there is a 1-in-3 chance of your dog being affected

A Longer Life

Our final major benefit of spaying is an increase in life expectancy.  On average it seems that spayed females live on average 26% longer than their entire counterparts.  That's a pretty big increase.  It seems that neutered dogs are less likely to die from infection, trauma, degenerative disease and vascular disease.  Instead they are more likely to die from immune-mediated disease and cancer.  Also, if a dog lives to 12 years of age then there becomes less of a difference between those that are neutered and those that are still entire.

There have been a couple of studies to suggest there is no difference in life-expectancy but on ballance it appears that spayed female dogs do live longer.

Behavior Benefits

The reduction in trauma noted here is likely because neutered dogs are less likely to roam the streets when they are on heat, looking for a dog to mate with.  As a result they are less likely to be hit by a vehicle on the road.  There are other behavioral benefits too to neutering, although these may be more noticeable and important in males.

Behavior clearly involves many different biological and environmental factors which all interact.  Neutering then is not a cure or guaranteed prevention of particular behaviors however neutered animals are generally less aggressive.  With other problem behaviors, a study in Vislas reported that those neutered before 6 months were more likely to suffer from various phobias.  If neutered after 6 months then the only difference compared to entire dogs was an increase in storm phobias.

Behavioral issues are really important to consider as these are actually the biggest cause of re-homing and death in dogs under the age of 3 due to euthanasia.  Proper puppy socialisation plays a huge role in preventing this.

Any more?

This covers all the major benefits of getting your female dog spayed.  There are still some other benefits however which include:

  • Preventing uterine and ovarian tumors, although these are very rare

  • Eliminating pregnancy related problems and the risk of cesarian section. These can be fairly common in certain breeds

  • Reducing sexually transmitted diseases such as Brucella and Transmissible Venerial Tumors. These can either be very common or unheard of depending on the part of the world you live in. Your vet can discuss the risk of these with you so you can get a true local picture.

Euthanasia of stray dogs

My final benefit of spaying is a benefit to the population as a whole rather than an individual.  Every year around 1.5 MILLION animals are killed in US shelters due to an inability to find new homes with about 6.5 million entering the shelter system annually.  In Australia an estimated 200,000 animals are killed every year and in the UK this number is thought to be 20,000.

That is a huge number of dogs and a global issue.  While some may have to be euthanized due to medical or behavioral reasons, many are simply victims of being unwanted and abandoned.  If your dog has puppies can you really guarantee that none of them will end up a part of these terrible statistics?

Should You Spay Your Female Dog? and When


So those are the benefits but what are the side-effects of being spayed and do these vary depending on what age a female dog is spayed?  Well there are some potential negatives to being spayed and some of these are more serious than others.  As for whether these downsides outweigh the benefits, that is up to you.

Surgery risk

The first, and perhaps most obvious concern is the risk of the surgery itself.  Any anesthetic and surgical procedure carries a degree of risk.  Spaying a female dog is a routine surgery, however it is also likely to be the biggest procedure your pet undergoes in their life and is more involved that most other common procedures.

While the complication rate is reported to be anything from 3-33%, the majority of these complications are minor, requiring no specific treatment.  At the other end of the spectrum, death rates are less than 0.1%.  Complication rate is something that does vary from clinic to clinic and given the nature of the surgery this is not something where you decide on who carries out the procedure based on cost alone.

A leaky bladder

The next risk of spaying is again well known and that is the risk of developing urinary incontinence.  It is generally accepted that the younger a dog is spayed the bigger the risk of incontinence,  Those spayed before 3 months of age in particular are at more of a risk.  Now this is likely true however the evidence is not consistent and is not really strong to make firm recommendations.  It is though for this reason that 5-6 months is the normal age from which we have spayed our normal pet dogs in the past and not generally younger than this.

As for how often this happens, I would say that this is a reasonably common issue in those individuals spayed earlier but one that is generally very well managed with medications, often being treated so well that the problem completely resolves so long as treatment is maintained.

Getting fat

So these 2 issues are ones that we have realized for some time and for many years they have influenced our recommendations as to age of spaying along with the mammary cancer and pyometra risk discussed earlier.  The other well known risk is the fact that spayed animals have a greater tendency to gain weight and develop obesity.  We need to recognize that one they have been spayed, their energy requirements change and exercise remains vital.

Putting in a few weight management strategies and making sure you are feeding the right amount goes a huge way towards preventing or correcting obesity and its associated problems.

Over the last few years we have started to understand that there are other downsides to being spayed.  With this realization has actually come more confusion and more difficulty in making the best decision for each individual dog.

We all love to making generalizations and the temptation is that when some new research is published we apply the new findings to every single dog.  With spay timing however, as you'll see, the message is mixed and what is true for one breed may be the complete opposite even in a closely related breed.  So let's jump into the other big risks that may be associated with spaying at different ages.

Cruciate ligament damage

Of these, cranial cruciate ligament (or CCL) disease is probably the most common, affecting up to 9% of individuals in at-risk breeds, with larger breeds generally being at a greater risk.  This is the same injury in dogs as an ACL rupture in humans.  The cruciate ligament runs within the knee and it can either fray or completely rupture and break.

This damage results in pain and instability within the joint and treatment generally involves surgery to ensure the best long term results.  This surgery is not cheap, so while the condition is correctable to a certain degree (arthritis in later life becomes more likely despite treatment), this is definitely something we want to prevent happening if at all possible.  So when does spaying increase the risk of damage?

The answer to this is that the risk really depends on dog breed.  We have evidence on 3 breeds.  German Shepherds neutered before 12 months were found to have a higher risk compared to entire females.  Along the same lines, Golden Retrievers spayed before 6 months of age were found to have a higher risk compared to entire females.  Surprisingly though, there was no difference in this disease regardless of when an individual was spayed in Labradors.

So what to make of this?  Well, it highlights that generalisations across all breed are difficult to make and suggests that some breeds may be more likely to suffer from cruciate ligament injury if spayed before 12 months of age.

Joint issues + dysplasia

The development of abnormal joints in the form of hip and elbow dysplasia is our next risk to consider.  Abnormal joints again leads to the early onset of arthritis and so a lifetime of pain management.  Again we have mixed messages depending on breed.  In German Shepherds, a breed that suffers with a lot of joint disorders, there has been shown to be no relation to being spayed and either hip or elbow dysplasia, regardless of the age being spayed.    Golden Retrievers are the same but Labradors spayed before 2 years have a higher risk of hip dysplasia.

Again, different risks for different breeds.

The Big C

Lets talk about cancer next.  This is the headline risk that many people will quote when advising against spaying.  Don't do it because your dog will get cancer and die.  But is this true?  Well we've already seen that spaying actually dramatically reduced mammary cancer.

In our German Shepherds, recent studies found there to be no link to spaying and the incidence of cancer, although some early work suggested a possible varying, inconsistent risk increase.

In Golden Retrievers one study found an increase risk in blood vessel cancer known as heamangiosarcoma in those females spayed after 1 year of age however a similar study found there to be no increase in risk.  With Labs and Retrievers there may also be an increased risk of lymphoma in those spayed between 6-11 months but this is also not a consistent finding.  Again, mixed messages are given in different studies.

For Vislas there may be an increased risk of mast cell tumors, lymphoma and haemangiosarcoma as well as some other cancers appearing higher in spayed females.  Interestingly this risk appeared to be highest when an individual was spayed after 12 months of age.

Perhaps the most compelling piece of data reported to date is the fact that in Rottweilers, there is a 1 in 4 chance of them developing osteosarcoma if they are spayed when they are younger than a year of age.  Now this is a particularly aggressive cancer with a terrible prognosis and so one that should be avoided if at all possible.  In Rottweilers this one point alone would make me want to wait until they are at least 1 year old before spaying them.

In other studies that have looked at the general pet population rather than specific breeds there has again been shown to be an increase in various different cancers in neutered compared to entire individuals.  This means that the risk is likely real but given the fact that there is much differing evidence out there firm conclusions are difficult to come to.

After all, what exactly does an increase in risk mean.  Does it mean that instead of a 1-in-1000 chance there is now a 1-in-900 chance or rather, like our Rottweilers does it mean there is a 1-in-4 chance instead of a 1-in-10 chance of developing osteosarcoma.  Clearly the latter is incredible important but the former may not be too much of an issue.  In most cases we just don't know for sure the true answer to this question.

Immune system breakdown

Our last set of conditions to look at, and one of the more recently studies, is autoimmune conditions.  These are caused by a breakdown in the function of a normal immune system with the result being several different diseases.  Of the conditions looked at, in half there appeared to be an association between neutering and disease.

Having said that, the nature of the study doesn't prove that this association is caused by neutering and while it may indeed play a role, these conditions are generally influenced by many different factors of which neutering is just one.  In fact genetic and environmental factors have been implicated in many autoimmune conditions.  It should also be pointed out that by and large these are relatively unusual conditions although clearly significant for those individuals who go on to suffer from them.

What does this all mean?

So what does this all mean?  Are you thoroughly confused?  If so I'm not surprised.  From all of this data it is impossible to make any sweeping generalizations regarding neutering and cancer risk.  Simple, one-size-fits-all rules are much more appealing and far easier to apply than a subtle, complicated decision based on various risks and benefits that are not fully understood.

If there is one thing that should be clear though it's that what is right for one individual may be wrong for another, be it because of the breed they are or because of the different risks that people are comfortable living with.  This means that you shouldn't feel under pressure to make the "right" decisions.  There is no such thing.

what i do feel is missing from the discussion about when to spay a female dog, or whether to spay them at all, is a discussion on the curability of the condition along with the cost of treatment

The right decision for YOUR family

What I do feel is missing from all of the facts and risks of disease that are discussed is a discussion on the curability of the condition along with the cost of treatment of a condition.  Some people will choose not to spay, instead being quite happy to watch for signs of a pyometra and act if they occur, as well as having any mammary masses removed as soon as they appear.

It's true that this approach will reduce the risks of these conditions being fatal (but not eliminate them) and may be a balance between these "curable" conditions and the other non-curable conditions that you wish to take.  This approach though has the potential to cost a really significant amount of money and with around 38% of entire female dogs suffering from either pyometra of mammary masses there is a 1-in-3 chance of your dog being affected.  

It may be though that this would not be something you would be able to afford and so these conditions effectively become "incurable".  Or you may decide that you are not prepared to take the risk that your dog dies from pyometra or untreatable malignant mammary cancer.  You may place greater emphasis on the fact that our spayed animals appear to live longer lives, potentially by as much as 25%.

And this then comes back to my interpretation of all this information and so the general recommendations I make at this point in time.  I feel that the benefits of being spayed outweigh the drawbacks and believe that all female dogs who are not going to be used for breeding should be spayed.

For small breed dogs I would still recommend spaying when they are around 6 months old before their first season.  For larger breed dogs however, where there is no risk of them becoming pregnant and where they can be successfully managed while on heat, I recommend delaying this operation until they reach 1 year of age or a little older.

You may disagree with this and that is absolutely fine.  All I hope for is that you are aware of, and have considered all of the risks and benefits of whatever decision you come to and understand that no option is completely free of risks.

Spay-related Diseases: the severity + affordability

I've had a couple of comments on two of my videos that I wanted to talk to you about. The videos that I'm talking about are "When should you spay your cat?" And the other one is "Pyometra and Dogs." You might not think that they're related too much you’ll see how they are and why they relate to the topic of when (and if) you should spay your female dog.


So someone left a comment on the "When should you spay your cat?" video:

"The Cats should be SPAYED or NETURED when they're at least a YEAR OLD, because if those procedures are done in their Juvenile Months, then they're at risk of MORE SERIOUS & FATAL HEALTH PROBLEMS, later in life, ALSO, their TRAITS & GENTIC STRUCTURE wouldn't DEVELOP RIGHT...👽"

Then I asked what their evidence and their reasoning behind that was and they linked to a post that was actually all about dogs and at the bottom said cats are different to dogs.

Either way, that comment highlighted for me that actually timing of spaying is not always black and white, that dogs and cats are very different and also the fact that you cant always believe what you read online (which I discussed in more detail in my article about the Dunning Kruger effects and evidence matters series)

The other video comment that I got was on my pyometra facts video and the risks of that.  It was from a lady whose dog sounded like it was in terrible way. I'm not sure what the outcome was, but she certainly didn't sound very well at all, having gone blind and with kidneys and liver that were failing.

It was in a really bad way, and it really just highlights my point that I make about when you should spay your dog.  It really depends on your circumstances. If you're able to monitor your dog, if you're aware of the risks of pyometra and mammary cancer and you're quite happy with those risks then leaving your dog unspayed may be acceptable to you

Remember though that for pyometra the risk is one in four dogs by the age of 10 will develop pyometra. The risk of death is relatively low if you get on to it quickly, but relatively low doesn't mean nothing at all, and pyometra is definitely a deadly disease.

I've seen a dog, I think it was about five or six years of age, come into the clinic. The owners had been away on holiday and the person looking after the dog hadn't noticed that it was unwell. It has lost a lot of weight, and unfortunately, within an hour or two hours of being admitted it passed away. It was just far too far gone and the infection was deadly.

For that owner and that dog, the thought is that clearly the owners would rather that they'd spayed that dog and it may be that it would still be alive today.  So it's really not straight forward.

If you're happy with the risk of pyometra and mammary cancer and you're happy that you’re able to pay the cost of those surgeries, then that's absolutely fine. We can either spay our dogs much later or even not spay them at all.

I think these black and white arguments, these bold statements that people make, just isn't getting to the nuance of this subject and the many others like it.  In reality, little in veterinary medicine is black and white.

Of course there are risks of spaying, certainly spaying early, that I’ve already discussed.  There are a few. One is bone cancer. In Rottweilers, one in four dogs if they're spayed before 12 months or around 6 months will develop a malignant bone cancer which is a terrible disease. It's horrible.

Cruciate ligament disease is the other one. Big dogs, our Labradors and retrievers, have the potential that spaying before 12 months will cause them to develop cruciate ligament disease. While cruciate ligament disease is a treatable condition, there will be potentially a significant element of arthritis to develop later on, and it's not a surgery that's cheap.

My point really is that when you see bold statements of fact, really we need to question them, and we need to think what is right for you. Like I said, you might say, "Well, actually, if my dog develops pyometra, that's an emergency surgery. That cost is going to be significant and I'm not going to be able to afford that," in which case, spaying your dog is probably going to be the best thing that you can do, because pyometra is really common. If money's not a problem, if your dog's insured (which pyometra and cruciate ligament rupture and mammary cancer removal would be covered), then that cost consideration may not come into it.

Either way, my point is, what's right for you is not necessarily right for someone else, so just be a little bit careful with what you read and what you take as fact, because some people can be very certain of themself when in fact they are mis-interpreting or mis remembering facts or mistaking other peoples opinion as clear cut evidence.

Now I know there is a lot of information and figures to take in but if you are still confused then please let me know any questions you have in the comments below and I'll try to answer them.  If it's your first time here also sign up to my newsletter to make sure you don't miss out on future content and allow me to continue to help you and your dog live healthier, happier lives.

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