I’ll start this post with the major caveat that I can’t tell you whether you should neuter or spay your dog. What I can do, however, is give you the pro’s and con’s of neutering your dog as it relates to dog training and behaviour. I’ll share what I’ve learnt in 6 years of professionally working with and ongoing study of dogs and their behaviour. I’ll also include some links to further reading so you can be as informed as possible. Ultimately, it’s your decision and it’s a decision that should be discussed in detail with your vet.
What is neutering?
So let’s start with a quick summary as to what neutering and spaying your dog actually means. Neutering is a surgical procedure where a male dog’s testicles are removed, also known as castration. Spaying is the surgical removal of a female dog’s ovaries and sometimes the uterus. This is also known as an ovariectomy or ovariohysterectomy. In both procedures, the end result is that the dog is no longer able to reproduce. For more info on the specifics and practicalities of neutering and spaying, have a look at the Royal Veterinary College’s website here.
Pro’s and Con’s of Dog Neutering – Pro’s
The biggest advantage to neutering or spaying your dog is, of course, to prevent unwanted pregnancies. This is the reason that nearly all rescue organisations will neuter dogs before they re-homed or have it stipulated in the rehoming contracts that new owners are required to abide by. Given the huge number of dogs needing homes currently, this is completely justified and makes total sense. Neutering and spaying, obviously and undeniably, is a very good way to stop your dog impregnating a female or becoming pregnant themselves.
Humping
The other major advantage to neutering and spaying is that it generally reduces humping behaviour. Please bear in mind that this is a very general statement! Neutering is certainly not a surefire way to stop humping. You can read more about the causes of and how to manage humping in our post here. There have been a number of studies done on the effects of neutering on humping in dogs. These studies typically show a reduction in humping, as well as urine marking and roaming behaviours in males, after they’ve been neutered. However, the most recent study I could find on this was done in 2023. The authors, Roulaux, van Herwijnen & Beerda, found that older intact dogs were as likely to engage in these behaviours as their neutered counter-parts. So it may be that simply getting older affects these behaviours as much as neutering does. In my experience, a reduction in humping is the most obvious and immediate consequence of neutering. However, if your dog is very humpy, we probably need to examine the root causes of this. Are they over-stimulated? There is likely more going on that’s worth investigating before rushing to neuter.
Health
When thinking about whether to neuter or spay, it’s important to look at the long term as well as the short term consequences to your dogs overall health. Most of the scientific evidence suggests that there are noticeable differences between breeds after neutering or spaying. Larger dogs, especially Labradors, may be more prone to joint issues and certain cancers if they’ve been neutered. For small dogs, there appear to be fewer, if any, long term health consequences (Hart & Hart, 2021). On the whole, the evidence for the health consequences of spaying and neutering is mixed. Older studies from the 1990s and early 2000s seem to indicate more positive outcomes. But the more recent the research suggests the effects vary from one individual to another.
Pro’s and Con’s of Dog Neutering – Con’s
So now that we’ve discussed the up sides of neutering and spaying, let’s look at the down sides. From a dog training and behaviour perspective, neutering your male dog can have the effect of negatively impacting their confidence. This seems to particularly affect their interactions with other dogs and even more so if they were already anxious, fearful and/or reactive. There is a bit of a myth, and plenty of misinformation out there, about how neutering ‘fixes’ aggression, especially between dogs. In my experience, the exact opposite is true!
There is a lot of evidence to this point too. Most studies done in the last 10 years or so find there is a small but statistically significant increase in aggression after neutering, particularly in male dogs (Roulaux, van Herwijnen & Beerda, 2020). Neutering at an earlier age, between 7 and 12 months, seems to have a particularly negative impact on how aggressive a male dog may be towards strangers (Farhoody et al, 2018). Most recently, Arroube & Pereira (2025) did a review of the studies done on the relationship between neutering and spaying. They found that a lot of the research was conflicting and difficult to make conclusions. Behaviour is open to interpretation and many studies rely on the self-reporting of owners, who may have varying opinions on and definitions of aggression.
In my experience, neutering/spaying often, not always, but often, aggravates any underlying behavioural issues that were present before the operation. As long as your vet is in agreement, I typically advise working on the behaviour and training before neutering or spaying. The surgical removal of a dogs sex organs is non-reversible obviously, so it’s important to do your research and be fully informed when making the decision. Which brings us nicely onto the potential alternatives to neutering.
Pro’s and Con’s of Dog Neutering – Alternatives
The most common alternative to surgical castration is chemical castration. Instead of undergoing general anaesthetic to be neutered, chemical castration is done between the shoulder blades with the dog awake. You therefore don’t have the same recovery time as traditional neutering, which is up to two weeks.
One of the major benefits of chemical castration is that it is reversible. The effects last roughly 6 months, so if there is a negative impact to the dogs behaviour like an increase in anxiety or aggression, guardians know that neutering is not going to be suitable for their dog. This can be a really useful option for many dogs and is like a trial of being neutered to see how it might affect the dog.
The scientific evidence on chemical castration has shown that it has no negative impact on a dogs working ability (Gfrerera, Taborskya & Würbelb, 2019). A 2009 study by Morsink found there was a significant reduction in humping/mounting behaviour in dogs who had undergone chemical castration too. It’s a great option to consider if you’re not sure whether to neuter your dog, chat with your vet for further advice. Unfortunately, there is not yet a female equivalent to chemical castration.
My take
In my opinion, the best case scenario is that your dog can no longer accidentally impregnate a female dog and it reduces humping. The worst case scenario is that your already stressed out dog becomes even more stressed out than they were previously, increasing the likelihood of them becoming fearful and potentially aggressive. If you have a young male and they are already anxious or reactive, I typically advise avoiding neutering unless medically necessary. Discuss with your vet the options and what’s going to be best for your dog. When it comes to the pro’s and con’s of dog neutering, there really is no one size fits all answer. It really depends on your individual dog. If you live in an area with a high dog population (we definitely do here in Folkestone!) It’s certainly worth considering the rest of the community too.
References
Hart, L. A., & Hart, B. L. (2021). An ancient practice but a new paradigm: personal choice for the age to spay or neuter a dog. Frontiers in Veterinary Science, 8, 603257.
Roulaux, P. E., van Herwijnen, I. R., & Beerda, B. (2023). Desexing dogs as a means of decreasing the generally regarded sexually dimorphic behaviors of urine marking, mounting, and roaming. Journal of Veterinary Behavior, 62, 47-52.
Roulaux, P. E., van Herwijnen, I. R., & Beerda, B. (2020). Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs. PloS one, 15(6), e0234917.
Arroube, A., & Pereira, A. F. (2025). Dog Neuter, Yes or No? A Summary of the Motivations, Benefits, and Harms, with Special Emphasis on the Behavioral Aspect. Animals, 15(7), 1063.
Farhoody, P., Mallawaarachchi, I., Tarwater, P. M., Serpell, J. A., Duffy, D. L., & Zink, C. (2018). Aggression toward familiar people, strangers, and conspecifics in gonadectomized and intact dogs. Frontiers in veterinary science, 5, 18.
Gfrerer, N., Taborsky, M., & Würbel, H. (2019). No evidence for detrimental effect of chemical castration on working ability in Swiss military dogs. Applied Animal Behaviour Science, 211, 84-87.
Morsink, D. (2009). Behavioural changes after treatment with GnRH implants in male dogs; the behavioural effects of a reversible chemical castration. In comparison: a literature review of the behavioural effects of surgical castration in male dogs.
What next?
- Looking for help with your dog? Contact us to arrange in person or online training.
- Read more blog posts here.
- Perfect Recall: Teaching your dog to come back when called every time. Our guide is free to download when you join our email list- sign up here.