Let’s talk about Neutering

As part of my continuing Professional Development, I have recently completed an excellent and well written course by the very knowledgeable Sarah Whitehead on “Canine Sex, Hormones and Neutering” and a webinar by Dr Naomi Harvey “Adolescence in dogs: From Brain to Behaviour”. Both of these have really enlightened me, and drove me to write a blog on the subject to discuss this and reflect on the pros and cons of neutering. 

Deciding whether to neuter your dog or not comes along with many opinions and beliefs, both positive and negative. It is a highly controversial, complex subject and could well be one of the biggest decisions you will need to make for your dog. 

Your decision needs to be on an individual basis, there are a number of behavioural, emotional and physiological factors to consider. If you are concerned when making your choice, it is always best to obtain advice from a reputable and experienced dog behaviourist, alongside your vet. 

I would like to start this blog by talking about my late dog Mickey who sadly passed to rainbow bridge, in November 2020. Mickey was born in a shed on a farm in Wales, and spent the first four months of his life in there with his litter mates. The farmer then rejected the whole litter, and Mickey and his brothers and sisters went onto a rescue centre in Binfield, called The Border Collie Spot. Mickey then sadly was passed back and forth between the rescue to four different homes, being rejected each time by each new home, for reasons of being ‘too nice’, fearful, and saying that his house training being non-existent. The rescue neutered Mickey (which is standard practice by any rescue to help with population control and prevent any unwanted litters), at around 6 months old. We were blessed to welcome him to our home when Mickey was 8 months old whilst under foster care, as kennel life became too stressful for him. He arrived very skinny, shut down, and suffered at the time with colitis due to stress, and scared of anything and everything. 

Due to Mickeys sad and traumatic start to life, he wasn’t able to be exposed gently through the process of habituation and socialisation to all of the common day to day sights and sounds, and environments most dogs have the opportunity to experience. I have come to more realisation that Mickey was sexually and emotionally immature and in hindsight I wonder what improvements to Mickey’s mental and emotional welfare would have incurred should he had not been neutered before he was able to sexually mature; or even at all. Luckily for Mickey we as a family have always nurtured our bond with our dogs, and given rescue dogs the time, love, patience that they need and deserve, and apart from Mickey always having a nervous disposition, he managed to live a wonderful, fun and fulfilled life with us until 12 years of age. 

There are many pros and cons with regards to neutering, and whatever your role is, whether you are the Caregiver, Vet, Behaviourist or working in rescue, everyone of these groups of people, whether they be in a professional capacity or a member of the public, will all likely to have a strong point of view, motivation, experience, belief and reason whether neutering is advisable or not, and when it should be carried out. Always remember when deciding that any research you read or hear of may not be unbiased, and over time science and evidence can change.

When to neuter or not is an enormous and tangled area, which can cause much confusion for the caregiver, and when making your decision it is probably best advised to approach this on an individual basis, as there is no one size fits all.

What someone thinks may be a negative outcome for one dog, may actually be the right and positive outcome for another. As I said earlier there is no one size fits all approach.

There are many pros and cons for neutering your dog, but please note this list is not exhausted, and please do not see it as the gospel truth, I am no expert and this blog is there just to bring about healthy discussion, all based on what I have studied and read. 


Pros for neutering

  • When a bitch is not spayed and goes through her season but is ‘not ready’, she may be less tolerant of a male dog’s attention, resulting in her demonstrating defensive behaviour towards other dogs, including lunging and snapping. If your bitch is to have the chance to get these behaviours repeated a few times it will likely become a habit and behavioural trait that may well carry on through their adult life. 
  • As the sexual hormones increase, you may see a change in your dogs’ behavior, including reduced obedience, more rough on play, intimidation play, bullish behaviour and low level conflict behavior. These behaviours will be greater if there is an early insecure attachment to you, the caregiver. 
  • Adolescent male dogs, may be harassed by other adult males including being mounted by them. 
  • Female dogs may like to take on the disciplinary role with the adolescent dog, with some bitches having higher levels of testosterone known as ‘androgenised females’ who may cock their legs and scratch up after they go to the loo, with a broader body. Some may say they would benefit from neutering?
  • Studies have shown there are higher cases of separation disorders in entire males than 
  • neutered males. 

Cons for neutering

  • Adolescence can lower the threshold in your dog in everything, with a possible increase in anxiety and fear around the second fear period, the ‘adolescent fear period’, which occurs anywhere in shorter bouts around 6 to 14 months. A fearful dog it seems would greatly benefit from testosterone which brings more confidence, that is provided through puberty; the hormones during adolescence are for sexual and emotional maturity, as the dogs brain changes from a juvenile into an adult. 
  • Neutering your dog may well reduce its competitive drive, as testosterone brings with it more confidence.
  • Studies have shown that testosterone decreases levels associated with poor cognitive performance as your dog has a need to become more autonomous and stimulated by their environment around them.
  • In bitches, any testosterone levels in a fearful dog, may help with their confidence and could possibly have an influence with early neutering.
  • Neutering before puberty denies the brain to mature. 

There have been many behavioural studies made after neutering has occurred, one in particular in Chile 2015 on free roaming dogs found that after neutering they found no changes in sexual activity at all, urine marking actually increased, no decrease in aggression, although an increase found in chemical neutered dogs, but roaming reduced hugely. 

Another study by Reisner 2005 found that in 1,053 springer spaniels there was an increase in aggression in neutered dogs over ones who were intact.

I guess what we must consider is that with all behaviours whether neutered or not that if a behaviour has been performed and rewarded, whether that be internally or externally it is very liked to be reinforced and repeated!


Pros for neutering


  • No risks with getting pregnant and unwanted litters
  • Prevention of the womb infection Pyometra, which may require lifesaving treatment
  • Huge reduction in the prevention of mammary tumours, where 50% are malignant and in a bitch 10 years and above it increases further.
  • Spaying may increase weight gain
  • There are other risks associated with not neutering, including uterine diseases. 

Male dogs 

  • Perianal fistulas (most common in older intact dogs)
  • Prostatic hyperplasia
  • Prostate disease, as prostate shrinks after neutering 
  • Removes the chances of getting testicular cancer
  • Levels of testosterone in adulthood seem to maintain the same levels between the ages of 1-5 years. 

Cons for neutering

  • Puberty brings about a maturity in the central nervous system and behaviour. 
  • Can increase Musculoskeletal problems and other diseases associated with this, including a risk in cruciate disease if neutered under 6 months.
  • Increase in hip dysplasia.
  • Testosterone closes the growth plates in dogs, which shows why dogs neutered early have long legs (my dear dog Mickey was a result of this a dog neutered in rescue at around 5 months old, he was the lankiest dog ever!
  • Increase in osteosarcoma and other tumours.
  • Studies and evidence link to urinary incontinence if before their first season

Adolescent period

Adolescence is a long period of development from a juvenile dog at around 5 months old, to an adult of around 18 to 24 months. Factors which change the timings can be due to the breed and size of the dog, and can even be influenced by diet and stress. 

Puberty happens within this period, of a much shorter window anywhere usually between 6- 9 months, and is where most of the activity happens, giving access for the hormones to develop into an adult brain.

Sadly, more dogs are handed over to rescue centres during the adolescent period, as adolescency brings about a need for individualisation, autonomy and risk taking behaviour. 

Adolescence is a vulnerable time in your relationship with your dog and should be seen as just as important, or even more so than the puppy socialisation phase. There will be a lot of brain chemistry happening around this time, and the internal feelings and emotions your dog may encounter during this time are much more powerful than any other period in your dog’s life. These internal feelings and rewards could be anything relating to food, fighting, success, winning, running and relief from fear….

Many caregivers feel that their dog regresses during this period as the relationship can start to breakdown and conflict can increase with disobedience, including being easily distracted when out, impulsive, and risk taking behaviours. Please do not worry! This is all normal behaviour for a dog going through the adolescent period, and not cause for concern. 

It has been said that dogs do see us as parents, and if there are attachment problems and issues with your bond, it is likely to impact on puberty, just the same in human teenagers with their parents. When we cuddle and care for our children and loved ones, and we bond, it increases the hormone oxytocin, and testosterone falls. 

If the bond with your dog is secure then these behaviours that a dog may present in adolescent period may likely be less. Ultimately, we want our dog to be more motivated to want to be with us when out and about and in the face or many distractions, sights, smells and sounds. In this time though should your dog show symptoms related to aggression, this may be a sensible time to reach out to a professional to help modify and manage this. 

There are numerous strategies for dealing with your dog when it is changing from a juvenile to an adult, with its huge surge in hormones:

  • Firstly, keep it as stress free as possible! 
  • Make sure you keep your sense of humour intact, you may well need it! I know humour has always been my friend in changing and challenging times!
  • Get them used to the vets with regular quick and lighthearted visits for a yummy biscuit, ideally from a puppy. This will make the process of neutering much better for them should you decide this is the route for you. 
  • Try to reduce the stressers in their environment, and as a priority work on your relationship and bond with your dog; this will greatly benefit the behaviour of your dog and help them to cope with the world.
  • By the age of 8 months old it is helpful to habituate your dog to as much as possible, although appreciated that some situations it is hard to expose your dog too.
  • Stay if possible, under the threshold for any reactivity or inappropriate behaviour, and rewarding freely any positive and calm behaviours. 
  • Be predictable from day one, whether you have a puppy or a rescue. Routine, and consistency is key. 

Training and management through puberty

Do as many lead walks as you feel is necessary, especially to manage your dog better and their interactions with other dogs and humans. If your dog is reactive when on the lead you may feel the need during the small phase of puberty to do your walks in very quiet areas, and up the mental stimulation and enrichment at home to compensate for this. 

Testosterone is correlated to aggression, but it does not cause aggression. Behaviours that bring about internal rewards such as relief, winning and success are huge self-reinforcers which will increase testosterone levels. This is much more powerful during the adolescent phase than any other time. 

Testosterone brings more desire for risk taking and competition, and aggression which may possibly become a habit in dogs if repeated on a few occasions, (including some dogs that started off fearful), may use aggressive behaviours such as lunging, barking, growling, as a strategy to back the other dog or person away; if this works then this will very much reinforce the behavior and some dogs will even use this strategy and come to enjoy it. This then quickly becomes a pattern, and in this instance, neutering may well benefit the once fearful dog. 

I guess, if you want to make success of this period in your relationship with your dog, and an easier life, try not to allow your adolescent dog to practice any behaviour of an inappropriate nature, such as intimidating play, rushing up to dogs, and rough or ‘bullish’ behaviour, whether it be motivated by fear or other. 

To promote and reinforce the good behaviour, you would want to look for positive social signals and friendly greetings in your dog, and these would include a soft and wiggly body, greeting other dogs in a curve and sideways before sniffing. Your dog would also when communicating with other dogs, should include space taking and space giving.

If you have a bitch and she is in her first season, it would be advisable to lower her stressors, and keep her from public places. Giving your girl some space with lots of training and enrichment activities through their season will benefit not just her mental wellbeing, but yours too. Two to three weeks of staying away from long walks can rightfully drive anyone crazy but use this time wisely to keep her occupied and happy. Your dog trainer will be able to advise you on the best things to do to get you through this successfully and painlessly. 

With everything, try looking at your dog’s interactions with other dogs in context. It is more correct to say what you see rather than label your dog and make any quick explanations. 

Provide as much training, enrichment and mental stimulation as you can, this will aid in bringing a calmer, happier dog throughout the day. 


As with all things, it is best when making your decision to do some research. Talk to the professionals, and look at each dog as an individual. What may be a good decision for one dog, could be a possible wrong decision for another dog. Unfortunately, it is not a straight forward answer. 

Possible questions you want to ask yourself that may bring some clarity, should include your dog’s temperament and social signals, along with past learning experiences. Help with an emotional assessment of your dog from a professional may benefit greatly. 

It is defiantly worth considering neutering a fearful dog at least once your dog has sexually matured, since testosterone increases confidence in dogs.  Although an excessively self-assured dog who is able to practice and enjoy aggressive and inappropriate behaviours, may benefit from neutering earlier.

Also, what you are hoping to achieve by neutering, and does your own research confirm this? Your dogs breed type, size, and their current health status will also be strong factors in your decision. 

I hope that this blog has given you more insight into this controversial subject, and the confidence to ask the right questions, and not automatically see neutering as ‘the thing to do’. 

“Build the relationship first, then the obedience will follow…”.

Dr Naomi Harvey