In the UK, it is widely advised that most female dogs are spayed if they aren’t going to be bred from. Traditionally, this was recommended to be done around 6 months of age. But in recent decades the appropriate timing of spays has been debated and now varies considerably. Generally, most vets now recommend spaying dogs later than this. Why is this? Can you get your dog spayed before her first season still? What are the pros and cons of doing so?
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Recap on Spaying
Spaying is the surgical removal of a female dog’s reproductive organs. Removal of the ovaries and uterus is termed an ovariohysterectomy, while removal of just the ovaries is an ovariectomy. Ovariohysterectomies are more commonly performed by vets in the UK, while ovariectomies are more common abroad. When performed correctly, both should provide similar benefits. A spay procedure can take place via traditional surgical methods, or laparoscopically – there are advantages and disadvantages to both techniques.
We’ve discussed the benefits of spaying many times before, but here are some in brief. Dogs are unable to become pregnant or be receptive to entire male dogs. This prevents risks to the bitch’s health during mating, pregnancy and birth, and stops unwanted litters being born. Spaying also prevents dangerous uterine infection (pyometra) and can reduce the risk of certain cancers. Many studies have shown neutered dogs live longer. There are drawbacks, of course, including increased risk of obesity, and possibly increased risks of urinary incontinence and certain other cancers. But generally spaying is a net benefit to the majority of dogs.
So why wouldn’t we spay a dog as early as possible for maximum benefit?
Benefits of Pre-Pubertal Neutering
Spaying a bitch before she has her first season is known as pre-pubertal neutering. This can be done as early as four-months-old in some cases, well before most dogs enter puberty. In some situations, and in some parts of the world, this is still recommended. Why is this?
Reduced Risk of Disease or Pregnancy
If a dog is neutered before their first season, there is zero chance they can ever become pregnant. It can be argued that leaving a dog until they have hit puberty risks them getting pregnant if not monitored closely. As above, mating can be dangerous to male and female dogs, and pregnancy and giving birth are one of the most dangerous times in a dog’s life. Furthermore, there will also be little risk of reproductive-associated diseases, such as pyometra, ovarian and uterine cancers. While a dog neutered at a year or so old will still have low risk of having these diseases (they are more common in older intact bitches), they are occasionally seen in younger dogs. Neutering before any reproductive hormones activate will eliminate the risk entirely.
Possible Effects on Certain Cancers
As stated above, there is some evidence that neutering can increase the risk of certain cancers in certain breeds; though it has not been conclusively proven. In some cases, there is evidence that pre-pubertal neutering reduces the risk of cancer compared to neutering later, especially for mammary tumours. One study found mast cell tumours were less common in Golden Retrievers neutered pre-pubertally; however another study found that there was no difference in Labradors. Similarly, a study showed Golden Retrievers neutered after a year were four times more likely to get hemangiosarcomas than unneutered or pre-pubertally neutered dogs. A study in Vizlas found the opposite was true, and dogs neutered younger were more likely to develop haemangiosarcomas. Other studies in different breeds have shown no obvious associations with age and cancer risk; so these conclusions are not certain.
Potential Safety
All surgeries carry some degree of risk, including pain, bleeding, infection, anaesthetic complications and even death. While the risks are relatively low in most dogs, the quicker and less complex the surgery, the better. Therefore, there is some argument that pre-pubertal neutering is safer than as an adult. Pre-season bitches are smaller and skinnier with less abdominal fat. This means the surgeon can find the reproductive system quicker and easier, reducing anaesthetic time. Furthermore, the reproductive system will be small and immature. This means it has less blood supply and thus a lower risk of bleeding during surgery, another potential complication.
Convenience
This is one aspect often forgotten with pre-pubertal neutering, and that is convenience. For owners wanting to neuter after the first season, they must know when the season is, ensure a surgery is booked in, and assume the next season has not already started. If these timings are missed, it can result in delayed surgery, an increased risk of surgery at an inappropriate time, or even frustration and not neutering their dog at all. Having a set time at around 6 months or so makes it much easier to organise, and is not long after the primary vaccination course so will be fresh in their mind. The surgery may also be cheaper, due to the smaller size of the animal and reduced anaesthetic time.
Charity medicine and dog shelters also benefit from neutering dogs young, so they do not have to hold them for months longer and can find them new homes quicker. In many countries, stray animal populations are high, thus while neutering strays early may not be the best for individual animals, as a population there is a net benefit to prevent more strays being born, and keeping shelters from becoming overcrowded.
Downsides of Pre-Pubertal Neutering
Despite some benefits, particularly with regards to shelter medicine, there are also some drawbacks to neutering a dog pre-pubertally.
Anaesthetic and Surgical Risks
A small size does bring benefits, but it can also lead to complications. Due to puppies’ low body fat percentage, as well as higher metabolism, standard drug doses for adults may not be appropriate for them. If calculated incorrectly, this could lead to underdose or overdose. Furthermore, they have less fat to warm them meaning they lose body heat faster. During surgery, becoming hypothermic can lead to slower recoveries and more complications. Finally, with less fat reserves, puppies are more at risk of hypoglycaemia and associated complications. Traditionally, we recommend starving dogs overnight before surgery, but this may be too much for pre-pubertal dogs.
All of these issues can be mitigated by sensible vets, but they do present risks.
Skeletal and Joint Disease
Just like in humans, reproductive hormones are important in controlling growth around puberty, especially the long bones of the limbs. Removing these hormones early via spaying can lead to overgrowth of certain bones and joint disease.
For example, it has been shown that cranial cruciate disease (and hip dysplasia in males) is more common in prepubertally neutered Golden Retrievers than those neutered later or left unneutered. German shepherds may have similar risks too. Obesity is likely to compound this issue, and we know that neutered dogs are more prone to weight gain, thus increasing the incidence of skeletal disorders, especially if pre-pubertal neutering has left them vulnerable to damage. One caveat may be that dogs neutered young may have abnormal gaits or joint conformation, leading to more being radiographed, thus incidental joint dysplasia identified more frequently than later-neutered dogs, and is not necessarily caused by the early neutering.
Urinary Incontinence and Vaginitis
We know that neutered bitches are at a higher risk of urinary incontinence in later life than unneutered dogs, as certain reproductive hormones are responsible for maintaining bladder tone. However it isn’t clear how much the age of neutering affects this risk. One study has found that pre-pubertal spaying increases the risk of incontinence, while another that it can reduce the risk.
A further study found no significant difference in dogs under 25kg. Some breeds, like Irish Setters, Dobermanns and German Shepherds, as well as dogs that have recessed vulvas, short or docked tails, or are obese, are more prone to incontinence as well. A study has shown that Labrador and Golden Retriever bitches neutered young were more likely to have recessed or immature vulvas. Though this study did not conclude the effect this would have, these sorts of conformation are a risk factor in developing incontinence. Thus, it may be safer to delay neutering in these sorts of breeds.
Vaginitis, or inflammation of the vagina, is more common in bitches under a year old. One of the risk factors is the conformation of the vulva, and a lack of oestrogen. Thus, if dogs are neutered early before the vulva develops, the risk of vaginitis may increase. It has been suggested that dogs prone to vaginitis should be neutered later, as vaginitis often resolves after the first season.
Behavioural Changes
Hormones play a big part in control of behaviour, so changing the hormones via spaying may affect a dog’s behaviour. There are unfortunately limited studies into behaviour and pre-pubertal neutering, because testing would be impractical. Data can also be skewed by the fact that less experienced owners are more likely to rescue dogs from shelters where they have been neutered early – the lack of experience can lead to more behavioural issues. Conversely, more experienced dog owners are more likely to neuter their dogs later or not at all. Furthermore, there are many other factors, including the physical stress of neutering, that affect a dog’s behaviour, so putting the cause down to one issue is impossible. In short, analysing the effects of neutering on behaviour is very difficult. Nevertheless, let’s take a look at what some studies are saying.
One large study of over 1800 dogs looked at the pros and cons of early neutering
They found 8 behavioural conditions that were affected by the age of neutering. Noise phobias and increased sexual behaviours were worsened the earlier a dog was neutered, but escaping from the house, separation anxiety and urination in the house were reduced. Barking, aggression and growling were also worsened in male dogs neutered young, but not females. However, this may have been due to the shelter associated with the study screening for aggression and euthanising them; aggressive dogs didn’t often live long enough to be neutered late. Another study showed female aggression may increase after neutering.
A similar large study of 2500 Vizlas found that dogs neutered under 6 months old were at a greater risk of developing any behavioural issue than neutering older or not at all. Interestingly, the fear of storms was the most common behavioural issue identified in pre-pubertally neutered Vizlas.
Remembering again that studies into behaviour are difficult and scarce, it does seem there is preliminary evidence some behavioural disorders may be more common in bitches neutered young. Anecdotally, many vets recommend waiting, or not neutering dogs with behavioural issues at all, for fear they may worsen after neutering. Certainly dogs with behavioural issues should not be allowed to breed, regardless of neutering.
Summary
Despite decades of early neutering being the norm, the veterinary industry has changed to reflect new teaching, and pre-pubertal neutering is less common. The evidence behind it is mixed; but it seems likely that dogs neutered pre-pubertally are more likely to have skeletal, urinary, and possibly cancer and behavioural issues than dogs neutered later, with only some breeds having a reduced risk of cancer. Surgical and owner-factors can be mitigated regardless. A lot more study is needed before firm conclusions can be made, and accurate answers for every individual dog breed may never be found.
Thus, in most cases, it seems safer to wait until at least puberty before spaying a dog, particularly large breed dogs, who may benefit from neutering even later than this. Outside the scope of this article, but something worth discussing anyway is the argument on whether dogs should be neutered at all. Certainly more and more evidence is showing the potential downsides of neutering, and some vets are proposing alternative solutions to prevent unwanted pregnancy. While we wouldn’t go this far, and neutering should still be advised to a large proportion of the dog population, owners should be made aware of the benefits and drawbacks of neutering, the unknowns regarding pre-pubertal neutering, and the alternatives such as hormonal implants, vasectomies and hysterectomies. Neutering is no longer a one-size-fits-all policy, and vets must take every case individually, rather than a blanket approach.
Sources and Further Reading:
- Complications of ovariohysterectomy procedures performed in 1880 dogs
- Associations Between Dog Breed and Clinical Features of Mammary Epithelial Neoplasia in Bitches: an Epidemiological Study of Submissions to a Single Diagnostic Pathology Centre Between 2008–2021 – PMC
- Prepubertal neutering of dogs — some risks and benefits | Companion Animal
- Neutering in dogs and cats: current scientific evidence and importance of adequate nutritional management | Nutrition Research Reviews | Cambridge Core
- A Prospective Cohort Study Investigating the Impact of Neutering Bitches Prepubertally or Post-Pubertally on Physical Development – PMC
- Clinical approach to canine vaginitis
- Vaginitis in Small Animals – Reproductive System – MSD Veterinary Manual
- Long-term risks and benefits of early-age gonadectomy in dogs
- Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas
- Congenital canine urinary incontinence – what’s why has my puppy ALWAYS been incontinent?
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