My dog’s really nervous after neutering – does he need some sort of HRT?

This is a really interesting question, and raises a number of really valid points. To answer it, we need to look in more detail the reasons why dogs behave the way they do, and the hormonal influences on them.

Common misconceptions

It is widely – and falsely – believed that neutering “calms a dog down”. However, an adult or adolescent dog’s basic temperament is relatively independent of testosterone, and neutering won’t make any significant changes to his intelligence or personality. What it can do is affect his emotional state, and what behavioural options occur to him.

So what does testosterone do?

In behavioural terms, testosterone has two main functions.

Firstly, it is the main trigger for a dog’s sex drive – so any behaviour driven by the need to breed will be at least partly influenced by testosterone levels. This would include roaming in search of bitches in heat, humping and masturbation (although see below!), and, interestingly, urine marking. All of these behaviours are reduced (if not eliminated) by castration.

The second is that testosterone does appear to increase the expression of aggressive behaviour. This might be an evolutionary hang-over from having to fight for mates, but whatever the reason, the threshold for initiating an aggressive act becomes lower the higher the dog’s testosterone level is.

So, an entire dog is more likely to respond to annoyance or frustration by snapping than a neutered one is. The exact mechanism isn’t clear, but testosterone is also a major factor in determining a dog’s levels of self confidence, so he may be more likely to start a fight because he’s more likely to believe that he can win it!

What does testosterone not do?

It doesn’t initiate any particular behaviour, it just alters the likelihood of that behaviour being expressed. For example, not all “sexual” behaviours are actually linked to sex drive – so humping and mounting can occur in neutered animals as well. These patterns of behaviour are “hard-wired” into a dog, but they can be used to express different things – for example, mounting may be an expression of dominance. Some neutered dogs also continue to hump, possibly because it has become a learned behaviour.

As far as we can tell, testosterone is also NOT involved in the vast majority of “unruly” or “disobedient” behaviours. While adolescent dogs are more easily distracted, and are full of energy, poor behaviour at this age is more often related to poor training.

So, shouldn’t castrating him make him less aggressive?

Unfortunately not necessarily, and for a very simple reason…

There’s more than one type of aggression!

Aggression between male dogs is mediated largely by testosterone; however, aggression towards people, female dogs and other animals is far more weakly linked to his hormones. If you think about it, it makes sense: if you’ve got to fight other males to get access to a mate, there’s no point in fighting against the females, or against other species who aren’t competing with you.

Aggression that is directed towards people, other animals, or generalised (anything that moves and looks suspicious) is most likely to be fear-based aggression. And unfortunately, fear-based aggression is often made WORSE (or even triggered) by castration. While it would be a nice story to say that dogs became anxious after castration because of the psychological trauma from the loss of their testicles, this doesn’t actually happen. What does happen is a fairly rapid drop in blood testosterone, the very hormone that was keeping them self-confident and relaxed in the presence of potentially threatening objects. So, we might well imagine that the dog’s thought process of “yes, that person’s a bit scary, but I’m sure I could take them so I don’t need to worry” changes to “oh no, that person’s scary, I need to drive them off before they can hurt me”. Without that confidence-boosting hormone, dogs who are prone to anxiety often get a lot worse.

So can we replace the testosterone?

In theory, yes. However, there aren’t any licensed products in the UK, and you could be storing up problems for yourself. As we’ve seen, testosterone has complex and subtle effects on the brain, it isn’t anything like as straightforward as many people think (and it still isn’t fully understood).

The best way to get on top of any behavioural issue, in an entire or neutered dog, isn’t to mess with their hormones, but to seek a referral to a properly qualified canine behaviourist. If you’ve got a problem, talk to your vet who will be able to arrange a referral for you!


83 thoughts on “My dog’s really nervous after neutering – does he need some sort of HRT?

  1. My female poodle cross 9 months old was desexed 2 days ago, she is now very nervous and anxious and hides, she will not eat, drink or play with her toys in which she loves. I took her back to the vets and they gave me pain medication I have been giving a lot of attention but nothing changed, I am at a loss of how to help her?

    1. It usually takes a week or so for dogs to get over the procedure – it is major surgery! – so keep giving her the pain relief and attention. If you think, though, she’s not improving despite the medication, or she seems really unhappy, go back and get her checked again; there are a number of possible complication, in particular wound infections (especially if she’s managed to lick at the area).

  2. Hi, I have a Romanian rescue. I had him at 7 months, he is now 13 months. He has spent the majority of that time absolutely petrified of everything and everyone; including other dogs. It hasn’t helped that he had haemorrhagic gastroenteritis 24 hours after we had him and he spent 5 days in intensive care. He also had a severe skin condition, coccidia, warts around his mouth, nails that had come away from the beds amongst a myriad of minor injuries. (I understood clearly what I was taking on; a knew he was a very poorly pup)
    So, ideally I would have liked to predominantly leave him alone to process his new life but, unfortunately he’s had to have a lot of medicines administered and interference to exasperate his already anxious disposition.
    This last month he’s been absolutely brilliant. He always was very good at understanding routines and what is expected of him, so training him is a dream. We’ve gradually started introducing him to other people and I ask them to ignore him completely and he is becoming increasingly interested in them. He won’t take treats if he’s nervous and he’s on a gastro-intestinal food only diet (he is thriving on this) so you cannot treat train him either.
    He has spent most of his life here scared of my partner unless we are out on a walk and he’s glued to him . But, this last month he has really bonded with him too. He’s always been fine with me and the three kids. He prefers women to men.
    So, my long drawn out question is… this last month he has really progressed in every single way. He’s some way to go, but the improvements are huge. We’ve managed to get rid of some quite complex little quirks and he’s looking strong and healthy with a thick, shiny coat.
    The vet says this is a good time to have him castrated because he wasn’t strong enough to cope with it previously. Do you think this could knock his confidence and set him back, if so, I’ll discuss with the vet maybe waiting for a few months; which is what my gut is telling me.

    1. It’s a really hard call to make. Statistically, it is more likely for neutering to make a dog more anxious rather than less, but that doesn’t mean it’ll happen in every single case! One option might be to talk to your vet about a contraceptive implant that will “turn off” his testicles, simulating neutering, but that will reverse itself in about 6 months. This might be something to consider, so that if it does have a negative impact, it’s reversible?

  3. My little 16 month old pug was neutered just over 3 weeks ago and he recovered from the operation really quickly . I’m so upset as he has now become extremely timid and much more clingy. I don’t mind him being clingy at all ? but to see him quite jumpy and looking so sad is very upsetting. If my husband and I are out with him and one of us goes into a shop he actually whimpers and it sounds almost like he is crying. I almost wish that I hadn’t had it done . We didn’t want to have him neutered But circumstances forced us too . He is still his playful lovable self but the timidity is so sad . He seems to have lost all of his confidence

    1. While this may indeed be a result of the fall in his testosterone levels, there are other possibilities for the underlying cause, so it would probably be worth having a chat with your vet to rule out any medical issues. If there aren’t any, then the best approach might be to seek a consult with a reputable and qualified canine behaviourist to help him work through it – your vet will be able to recommend someone suitable.

  4. We spayed our 4 year old female poodle 3 weeks ago and now she is showing signs of fear (tail tucking, crying, restless and heavy breathing) only at week 2. She was still her happy self right after the surgery for the entire week. She wouldn’t even play with her favourite toy or eat normally. Would this Behavior prolong or even stay permanent ? I’m really sad to see her change into a dog that I don’t recognise

    1. From what you’ve described, I think you need to go back to your vet – this sounds like it might be a complication from surgery; I wouldn’t expect behavioural changes that dramatic or that fast in a female dog after spaying.

      1. New research is showing exactly what is described here. People are naive to think they know all of the important roles hormones are responsible for within the body. “Fixing” dogs started in the 30s, and only became a popular practice in the 70s dt a population boom. Prior to that it was considered cruel. In Norway under The Animal Welfare Act it illegal to “fix” a dog without a medical reason, as it is still considered inhumane. I think most of the time we just listen to vets who are taught the status quo. You can do a vasectomy or a hysterectomy, and keep the ovaries, and still prevent unwanted puppies. I own a wonderful intact male, and damn it for the first few years he was a lot of work and responsibility. Deciding to own a dog should mean you’re up to the task. Other dogs are triggered by his hormones (because they don’t have any), barking and lunging, while my dog stays calm. Then he gets blamed for being intact. I think within 10 years we will regret what we have done to our beloved pets. There are certainly side effects to spaying or neutering your dog. Case to case basis occasionally maybe – otherwise it’s a money grad. That actually the option of my local police dog trainers as well. I won’t be buying new hips, knees or elbows. Bring on the judgment… Owning an intact dog is harder – but they aren’t just here for our convenience. We are the ones who need fixing.

        1. We’ve actually got a whole week of content lined up later this month to discuss this, because as you say, it’s a really complex area. There are many good health reasons to neuter (we do see a LOT of older dogs dying from preventable pyometra, for example), and many good reasons not to; which is why we want to look at all the evidence!

  5. Hi,

    My dog Max is a German Shepherd mix. We’ve had him since he was about 4 months old. We’ve been taking him to the dog park since then and he’s done super well with every single dog. He’s never even shown a lick of aggression, even when a dog has lunged at him. We got him neutered about 8 days ago, and he’s been aggressive towards puppies and any new dogs. These incidences are extremely surprising and scary, as Max has actually bitten. I don’t know what to do because before we neutered max he was a perfectly friendly and playful dog. Now I am scared of him biting other dogs. He just turned one year old.

    1. That sort of dramatic behaviour change is unusual – hormone levels don’t drop off that fast in most dogs. I think I’d get him checked out by your vet – it’s likely to be a result of discomfort from his surgery. If he checks out medically, then talk to your vet about a referral to a qualified canine behaviourist, as this behaviour can usually be resolved with time and care.

      1. I love how this vet automatically disqualifies that anyone who desexed a male dog and they show signs of aggression that it is something else my 16 month old Boston not desexed intact has been only attacked by at least 50 desexed dogs and most of the time he tries to run away. I call B.S. I get it your job is a vet is to advocate to have every dog desexed yet what about Cushings I see that most dogs desexed male or female by 9-10 get Cushings while intact dogs mostly don’t and desexed dogs are terrified of fire works while intact dogs don’t seem to care also lighting and thunder as well/

        1. I did write a whole blog about the possible behavioural side effects… It’s just that they’re less common than medical causes, and while it isn’t my job to advocate neutering, it is my job to recommend that medical causes be ruled out before starting on much more complicated behavioural therapies. It’s also true that many of the comments don’t fit the normal timeline for testosterone-depletion behavioural changes. It takes many weeks or months before the effects of testosterone wear off, because of the latent gene activation effects of the hormone. Aggression within a few days is usually pain or fear related, as the pre-neutering testosterone is still working.
          Watch this space, though, because we’ve got a whole series of blogs on the pros and cons (yes, really!) of neutering coming up next month. In the UK there’s a really interesting debate at the moment in the veterinary community as we’re looking at the pros and cons, and re-evaluating a lot of the older evidence. We genuinely do want the best things for our patients, but the balance of risks and benefits is much more complex than most people realise – and the data is only now starting to emerge to give us an evidence base to work from.

  6. I spayed my dog few days back. She is very nervous and hides from others. We feel that she has lost her confidence. She is not playing. And when we give give her treats she is very suspicious. This is really sad… because she was always a happy dog who loves to play around… is there something we should do.. and we did get her checked and there is no infection.

    1. She may well be very nervous after surgery, that’s not uncommon – it might be worth talking to your vet to see if she needs more painkillers. If she’s still nervous several weeks on, then it’s worth getting a referral to an up-to-date (e.g. non-force based) qualified canine behaviourist – your vet will be able to help you find one. However, alterations in behaviour in female dogs are rarely due to hormonal changes, because for much of their year their ovaries are largely inactive anyway.

  7. Painting simple you are taking away the dogs manhood when you neuter him.. Mm. They’re born with testicles for a reason

    1. There’s no evidence that dogs are aware of any changes following neutering. The effects of sex hormones are far more subtle and complex than most people imagine, and anthropomorphising our dogs doesn’t help us to understand them at all.

  8. So I just got my dog neutered yesterday an when I came home from work i let him out to eat an go to the bathroom an I have a puppy an he has never tried to keep her from going into another when he was eating and when she was drinking he tried to go after her an I’m scared that he will hurt her an I don’t kno what to do about it I got them separate right now I’m so lost with this

    1. If he was neutered yesterday, he may still be feeling drowsy, or he may be a bit uncomfortable – either of which might make him fell grumpy! My advice would be to call your vet and let them know, as he may need a little bit more pain relief. Behaviour changes immediately after neutering are usually due to post-operative discomfort rather than anything else. Remember, it takes 4-6 weeks for testosterone levels to fall anyway, which for most dogs is plenty of time for them to get used to it.

  9. HEY. I have a cocker spaniel, it has about 1 year and a half and he started to have a problematic behavior, he’s extremely aggressive with strangers in particular, but even with people he already knew, as well. Like it doesn’t trust people anymore or something. He was neutered 2 weeks ago, it may be a coincidence, but before that he was a really friendly dog!! Or may be the hormonal changes. I really don’t know what to do because i’m affraid be will bite someone. I mention that he never suffered a trauma before or something like that. With me, it doesn’t have any form of agression.

    1. I think the first thing to do is call your vets and get him checked up – post-op pain or complications are common causes of behavioural changes after any surgery (and much more common than such a dramatic change from neutering).
      If there are no medical causes, then I think a referral to a qualified canine behaviourist may be needed – your vet will be able to recommend a good local one.

  10. I got my 8 month old dog neurted 2 days ago and he’s been panting and has been breathing alot heavier. I am getting nervous because he’s never been like this before my vet is currently closed is this normal what can I do. HELP

    1. Call your vet or your local emergency vets – this could be a complication from the surgery; most likely, this is breakthrough post-operative pain, and additional pain relief is needed, but you need to speak to the duty vet for advice.

  11. Good afternoon, we have three dogs two males and a female 2 days ago we had 1 male neutered and the female spayed. The neutered male has now become very aggressive growling at myself my husband, kids and will not stay away from the female. he is also very aggressive towards the other male. He whines and barks incessantly at the door if we try to separate him from her. If we put him in the backyard he jumps over the fence and scratches at the doors or runs around the house barking constantly. We have never seen this behavior in him, he is normally a very calm sensitive dog. As a family we are very concerned and upset and want the best for him and her. I’m not sure if this is useful information but he is a pitbull mix and our female is a Australian Shepherd mix both rescue dogs.
    Thank you in advance for any helpful information.

    1. This is very unlikely to be due to hormone changes, so soon after surgery. It’s far more likely to be due to post-operative pain or discomfort. We would advise having a chat with your vet about getting him checked over, and he may need some additional pain relief.

  12. My dog is almost 2 years old. Had him neutered 5 weeks ago and he’s never been aggressive until yesterday. He took off after someone across the road. I have him on a training collar and it stopped him before he got close to them. He is highly trained and listens well but he has played with this person before and has never acted this way. He is even starting to nip at me and I’m not sure why. Could this be from being neutered?

    1. It’s impossible to say for sure. I think the best thing to do is have a chat with a qualified canine behaviourist – your vet will be able to recommend one, and I understand that many of them do remote consultations now too.

  13. Our 7 months old male puppy was neutered three weeks ago. His scars have healed nicely and he is in good spirits. However, he has started jumping up on us more than he did before, and very often with the purpose to hump. Before the operation he humped cushions or toys sometimes, but it seems this behaviour has been worse since the operation. The opposite of what we expected. Will this settle down or is it too early to say?

    1. That humping could just be misdirected excitement! The link between hormones and sexual behaviour in adolescents is complex, and learned behaviour is very important too. It’s also important to remember that humping isn’t always sexual – it can be triggered by a range of different emotional responses. It will probably settle down in time, but it’s too early to say for sure, I’m afraid!

      1. Hi! I have a two year old Pom that we rehomed in December. He came from a loving home but mostly lived inside and was never trained to be off lead. Now he lives with us, we want to train him to be able to enjoy being off lead in safe environments like the park, so we decided to get him neutered. That was 5 weeks ago and he’s had the all clear from the vet that medically it went well. Since the op, he’s been growling and barking at other dogs (while he’s on the lead) in a way that he just wasn’t doing before. It appears to have made him more anxious and I just don’t know how to deal with the situation when it happens. I really want to be able to get him off lead but am too nervous to start any training while he’s behaving like this with other dogs. We’re also obviously on lockdown so I’m unable to seek the help of a trainer. Any tips? Thanks!

        1. While the neutering may be a factor, I suspect that general family/household stress from the lockdown is more likely to be the issue! While I would advise you seek advice from a qualified canine behaviourist (your vet will be able to recommend a good one, and some of them do do video consults now), in the meantime, focus on keeping things calm. Consider using DAP diffusers too, and talk to your vet about any calming supplements that they can recommend.

  14. Hi David! Our staff cross rescue (1 year 7/8 months) was spayed maybe 5 weeks ago now. Before she’d run off after other dogs to play and be hard to get back because she was having so much fun! We’ve now noticed that she’s more or less not interested at all in ANY other dog, and if they run at her her ears go back and she looks very on edge/scared. She’ll give a little growl if they pester her or if they try take her stick. She never did that before. Would you say that is something worthy of contacting a behaviouralist or something that she might just settle in to?

    Thanks so much.

    1. She may well settle down, but any sudden behaviour change in a dog is always a bit of a concern. One possibility right now might be household stress due to Covid 19 and lockdown bleeding across, so you could try general calming and de-stressing approaches first – DAP, for example. Your vet will be able to recommend both products and a good local canine behaviourist.

  15. Hi, I have an 8 month old who I was advised to get neutered when he was 6 1/2 months, before he was just excited all the time but now he seems genuinely depressed and that hes not happy with us, he still listens most of the time but he sometimes seems like he really just doesnt want to come back, he has started suffering really bad from anxiety so he will come back of you walk away. Hes also seemed to start to get fixated on things in the water, I’m slowly training him to like water because I live in a place with a big forest with lots of streams and beaches and a loch, but if he sees a stick in the water he will not leave it, he will literally run away to go to this stream in the woods to find a stick he saw there yesterday, and he will just sit and pace aye the waters edge crying that he cant get it. And the other day my neighbor came in and my dog was barking, snarling showing his teeth and had my cornered my friend against the wall basically until I’d came out the bedroom, which he’d never done before amd as soon as I came inti the same room he was fine. But I’m unsure if that was a way of him feeling like hes guarding me and the house but this friend has always came in and out as he pleases and never had this issue, also we walked him together and id looked away to take a call for a second and he bit my friends hand to get the ball he had, which he never does with me but he seems to be sort of bullying my friend when I’m not here ? Dont know if that would be a behavioural issue linked to anything.

    1. While neutering might be a factor, I think this sounds more like a behavioural issue rather than a hormonal one. My best advice would be to talk to your vet about getting a referral to a good, qualified, canine behaviourist, to get on top of these issues before they become serious. Good luck!

  16. Hi. I got my dog neutered 10 days ago. His mood has completely changed and has been aggressive for two days in a row. His aggression is so severe that he won’t let us touch his crate. I’m not sure what to do. We gave him a sedative yesterday prescribed by his vet and he still was very aggressive by barking and growling. He’s a blue nose Pitbull and will be turning 2 in June.

    1. This is very unlikely to be due to hormones (it’s too quick!) – most likely, he is suffering from post-operative discomfort e.g. pain or infection. I’d strongly suggest you call your vet and get him checked.

  17. I have an 11 year old chihuahua/dachshund rescue. He was neutered when he was about 3 months old. He has had thunderphobia since he was a puppy. Loud noises cause him to scratch and tear up carpet, or anything he can get to. He also jumps quite often if you allow him to sit in your lap or if you start to get up and walk away. He is about 18 lbs so he isn’t quite big enough to hurt but it’s annoying. If it starts to rain he immediately starts shaking and drooling. I’ve tried Benedryl and it doesn’t do much if anything at all to relieve his anxiety. Could his hormones be unbalanced and causing this constant behavior?

    1. That should have been “humps” although he is very jumpy too. He constantly humps people if they give him any attention at all.

      1. This is much more likely to be a behavioural problem than a hormonal one. I’d strongly suggest you talk to your vet about a referral to a qualified force-free canine behaviourist; also, try to avoid giving human medications, as the effects on a dog’s mental state can be quite unpredictable.

  18. Our 5 year old chihuahua is normally a little Sweetie. Every so often, say, once every week or two, he cannot settle down, cowers ,and just acts anxious. My partner, who truly “owns” him is in and out because of her job. he spends 90% of his time with me and has a fine time MOST of the time. He and my 12 yr. old beagle mix are GREAT Friends. The little one seems genuinely happy and well adjusted MOST of the time. His “anxious Times” tend to last from a few hours to as much as an entire day. I cannot figure this out.

    1. I think the best thing to do would be to try and find a qualified canine behaviourist who can advise you – there are so many possible issues that I don’t really want to start in on this! Determining the cause could be quite complicated, but your vet will be able to recommend a suitable force-free expert.

  19. Thank you. It was suggested by two vets that I try benedryl. I will check into a canine behavioral specialist instead.

  20. My 4 year old chihuahua mix was neutered 2 1/2 weeks ago. 2 days ago he started to become lethargic, and not wanting his favorite treat and very limited appetite. We took him to the vet yesterday. Labs normal, stomach x-ray essentially normal (some gas and poop). They gave him fluids under the skin and told us to keep an eye on him. Later that same day he started to develop increased respiratory rate and appeared to be in some distress. Took him to the ER vet. Got a pain shot and that calmed the respiratory problem down. I’m concerned why he’s all of a sudden lethargic, almost refusing food & treats and developed the respiratory symptoms. Any recommendation for me to bring up with his vet?

    1. My suspicion would be that the neutering is a coincidence – the only think that seems at all likely would be either a wound infection or possibly some sort of adhesion, but I wouldn’t say they’re common. Definitely time for more tests if it doesn’t resolve on its own… Good luck, and please let us know how you get on!

  21. Hello, I have a 12 month old husky mix that I have scheduled to get neutered but now I’m debating it. He has had multiple behavioral problems including leash reactivity and warriness/aggression to other dogs/strangers. Our trainer told us thats he has fear based aggression when he was 7 months. He still has behavioral problems but he has calmed down a bit. Could this be due to an increase in testosterone as he has matured? He has never has any sexual/hormonal based problems (humping/wandering). Considering the fact that he is still timid/warry/aggressive and it’s most likely not due hormones, would neutering him only make his fear based aggression worse? I’m in the process of training him and he is getting better, but I’m scared that if he gets neutered, it will be an experience that just plumits his self confidence. Should I hold off on getting him neutered right now until he has more confidence?

    1. This is a really hard decision; however, my personal opinion is that in a dog with existing fear-based aggression, neutering should usually be delayed. The health risks from being entire in male dogs are significantly lower than in females, and are more long-term too – there are few medical risks in delaying neutering (unlike in females, where every season they have increases their risk of breast cancer). The one major risk factor in entire dogs is roaming searching for a mate and being hit by traffic, so if you can manage that risk, I would definitely be considering delaying.
      That said, there are other opinions – there are risks in both routes, and I don’t know him as an individual, so I would suggest you discuss this with your vet and (if you have one) a qualified canine behaviourist.

      1. Wow I can’t believe this all I hear from everyone is “it’s much better to fix your dog than to not” but thank you everyone for all of your information – I don’t think I will take my dog to his appointment to get fixed anymore.

        I have an 8 month old rotti/Catahoula and he’s super happy and playful. But he hates when we go for walks, he runs and hides and I can’t even keep a collar on him because he will hide all the time. Once we are on the walk he is okay but he will bark and go towards people who are walking by (like he’s protecting me) but his tail is still wagging. I tried a harness and he wasn’t afraid of it like the collar.

        He had an ear infection a few weeks ago and the vet put a cone on him and he was so afraid of wearing it he would sporadically burst and jump and freak out, it was so bad he could have broken his leg or something else. I had to take the cone off and buy a no flap ear wrap so he couldn’t scratch his ear and that worked much better.

        He occasionally humps my 5 year old fixed female pitty but she doesn’t mind and gives him a growl when he’s bugging her.

        My 8 year old female chihuahua is so grumpy and growls and barks at him all the time and he’s so good with her he just wags his tail and leaves her alone – even when she nips at him.

        So if there is any chance that neutering him will make him more freaked out and/or a possibility that he will snap back at my chihuahua than I will definitely hold off!

  22. Help!

    I have a 9 month Golden Retriever who was neutered 8 days ago. He’s never been aggressive towards any human or dogs, he loves everyone! Prior to being neutered he did have a little bit of leash aggression towards me but for a few weeks leading up to him being neutered it had stopped completely. Now everytime we go for a walk or to take him to do his business he lunges, growls and jumps up and bites my hand or arm. I am covered in bruises. It is usually
    after someone says hi to him or we pass another dog. He’s never aggressive inside and after he has calmed down he’s totally normal.

    Please help!

    1. I doubt that this is due to the drop in testosterone – any behavioural changes usually take a lot longer to develop. I’d definitely get him back to your vet though as this could well be a sign of post-op discomfort.
      If not – time to ask your vet for a referral to a good, qualified, canine behaviourist.

  23. Hi, firstly this column and your advice have been great so please keep up the great work 👍 We have a 2 year old working Cocker who is due to be neutered for next week. He got him at 4 months as a rescue and started off being very timid but has gradually got more confident, let more people stroke him, plays with other dogs etc. His main issues are poor recall, some humping of other dogs in the park and getting
    very excited before going on a walk. The vet 9 months ago recommended we wait until neutering as he needed the testosterone to be confident. My worry is by neutering him now, his confidence will be irreversible damaged and he’ll go very timid again. All his exuberance is manageable and he isn’t aggressive. Do you think it worth going through with the neutering?

    1. There’s no way to know for sure. By 2 years, it is unlikely that neutering would have a dramatic effect on his anxiety levels – but it’s also quite unlikely to affect his energy levels, and even his humping might well be a learned behaviour by now. I think have another chat with your vet and a good canine behaviourist if in doubt, who can give you individualised advice. Good luck!

  24. Worried now. I have a 2.5 yr old Male silver American Field Labrador . We live on the lake I’m a Senior Lady thought I was buying another English Labrador. Was I wrong! Energy I’m getting ready to neutered him. He’s always playful to much and more energy than I have yes, now a roamer, always a car chaser and I’m in a dead end 6 acres. Thinks he’s the alpha. What is this going to do to him? I have a 16 yr old English lady and a dropped off black bait small American field. She’ll whip on Caesar the Silver male. Please advise I ❤️ them all just hard with 3 and now this AKC male. I’ve had since 8 weeks 2 raised in my home awesome manners. Will this change him? If I decide to donate or regime him because of size and activity I don’t want him to end up in a puppy mill.

    1. It’s very unlikely unless he’s already shown signs of significant fear or anxiety. Most dogs don’t undergo any change in personality – it’s just that in occasional (not common!) cases it can worsen existing problems. Hope that helps!

  25. Hello! Very glad I came across this thread, as it’s not full of the ‘my dog was fine the next day’ stories!

    We got my 10 month old cockapoo neutered last week. He is your typical cockapoo – happy, friendly, excited to see people and especially excited to go for walks. But since neutering, he’s barely taken a step. He seems in pain lying down and shuffling around to find a position and spends most of his time lying down (although he will sit on his back legs). The only time there’s been further movement is when we’ve had visitors and he’s been excited to see them, or when he goes to the toilet.

    His wound is healing nicely and I’ve bothered my vets three times already to express concern that he’s not walking. They keep saying he’s a cockapoo and it’s typical of the breed to react this way. Today he’s less sad but still not his usual self.

    1. Some dogs do seem to have a much lower pain threshold than others – and cockers (and related crosses) in my experience are among the more sensitive souls! It’s worth bearing in mind that post operative discomfort is really quite common (as you’ve seen on here!). Fortunately, it does sound like he’s starting to get over it, but if the wound feels tight when he walks, he might well not want to move around as much. Is he due a post-op check soon? It might be a good idea to get him seen by the vet or nurse and have them examine his wound, as if it is tight, a little bit of extra analgesia using a dog-friendly anti-inflammatory might be needed.

  26. Hi. My dog has been socialized and training since 10 weeks old (now 11 months), so I would say that there is no reason for him to be aggressive towards people and other animals. I’ve tried all the tricks in the book, took my trainers advice but when he sees another dog or a person he doesn’t like, he just wants to go at them. Luckily he is always on a leash. He only likes certain people but is not a fan of other dogs. I’ve done the training and socialization, but it hasn’t helped a lot. I’m just scared that when he does get bigger and I can’t handle him, he will take off and something bad will happen. Do you think I should get him neutered? I don’t want his playful personality to change and I’m seeing a lot of comments where this has happened.

    1. Personality changes are actually pretty uncommon – but of course in a blog like this, you’ll get a lot more people commenting who have had problems than you do in the general population!
      I would say if there’s any question that the aggression is fear-based, neutering is likely to be more of an issue. Might be worth talking to your vet about a referral to a good, qualified canine Clinical Behaviourist to see if you can get to the bottom of the underlying cause for his behaviour?

  27. Hi, I’m very reluctant to have my male dachshund neutered at 22 months old but Im being told its a case of having to because he has an undescended testicle. He can be quite a nervous dog around new dogs and can be quite jumpy but never aggressive. I’m concerned that getting him neutered however will turn it into aggression. Our female daxie was neutered at 14 months and she turned her anxiety into aggression so we’ve been put off doing it again. I know that the undescended testicle can cause a risk of cancer but does it have to be done by 2years old or can we wait longer?

    1. The longer the testicle remains in the abdomen, the higher the cancer risk. There’s also a significantly higher risk of the testicle twisting which appears to be incredibly painful, and is potentially fatal.
      I think it’s time to talk to your vet about the options; at 22 months, the risk of behavioural changes is lower than at a younger age, but the cancer risk is definitely starting to increase.

  28. I need advise regarding my extremely anxious and timid 9 month old rescue pup. I initially fostered his brother and him 4 months ago and they were both very timid, but together they grew more confident and began to enjoy walks as initially they would cower and wee at the sight of a lead. My pup was neutered 4 weeks ago and his brother was adopted 3 weeks ago, since then he has become alot more timid. He jumps at every single noise in the house and will randomly bark at objects, but his walks are what are conserning me the most. He now runs away from his lead and has to be carried to the door and coached out side, he spends the whole walk with his tail between his legs, whining and pulling to go back home. I only take him on short walks as I know the whole experience is so distressing for him. The slightest noise and he coweres and pulls more. He has no interest in food in this mindset so positive rewards will not work. I have looked into training but it is so expensive. What can I do to get my dog more confident on walks again?

    1. Gradually build up positive experiences – find what he likes (fuss, play – doesn’t have to be foods) and use those as the reward. However, a clinical behaviourist is a good idea in situations like this.

  29. I rescued a pure bred (un-neutered) Yorkie when he was very young and he has always been really sweet. Now he is coming up on 2 years old and tends to hump everything in site, even the air, for about a week at a time. He will be humping for a while and then the next couple of weeks will be normal, then he randomly will start humping everything for another week.

    Lately he has become extremely mean when trying to put something around him, like a harness or a lifejacket that clips on his underside or if you try to touch his butt. We used to shave his back end so he didn’t get poop stuck in his hair but now we can’t. If we try to grab it with a paper towel he will furiously bite and make my partner and I both bleed. Today I was wearing kevlar gloves and was fine when he was biting but he noticed it didn’t phase me so he chomped as hard as he could and twisted his body and broke my skin through the gloves! He is fine as long as we aren’t touching his underside / back end. Could this be because he is sexually frustrated? Will he stop being evil after he gets neutered?

    1. This doesn’t sound like sexual frustration, this is either pain or a behavioural issue. I’d strongly recommend getting him checked by your vet for medical problems; and if nothing found, a referral from your vet to a qualified canine clinical behaviourist.

  30. I have a German shepherd male dog who is intact and is now about to be 2 years and 2 months old. Unfortunately he has been aggressively attacked by pit bulls twice when he was about 1.5 years old or so. One of those pit bulls had just been neutered as well, which I thought was interesting to note. My shepherd has always been very social and friendly with dogs, but after the second pit bull attack he definitely became more sensitive towards dogs that may tend toward aggression or defensiveness. So now my shepherd can be more on the defense himself when we are walking and see a dog that he either isn’t sure about or Immediately senses is going to be aggressive. It’s as if he is anticipating nasty attitudes from other dogs sometimes. He is conflicted though because really all he has ever wanted to do with dogs is play chase and wrestle around! So he will lay down on all fours waiting for dogs to pass us usually, or on occasion to say a quick hello if they seem really obviously friendly and secure. We avoid pit bulls for the most part now because I’ve seen their behavior be instantly unpredictable twice now, even though I know they aren’t all like that, but I feel like you never know. When I read about the fear-based aggression I definitely Thought of my shepherd and his newer behavior towards certain other dogs when we’re walking. So I haven’t been leaning towards neutering him in general, but now I’m really thinking that it’s not a good idea to neuter him after readinG this article. We currently started working with a trainer using the clicker and I definitely think it’s helped already curb his anticipation of aggressive dogs, although I still find myself avoiding Other dogs as much as I can when we are walking. He has played off leash 2 with one or 2 other dogs at the dog park and been good. He just gets too excited about playing and struggles with recall when I call him over which is a big problem that we will be working on with the trainer. Please offer any feedback if you feel qualified to do so based on your experiences or professionalism if you work with dogs and German shepherds in particular. I’ve been debating whether to neuter him or not…. what do you think and why?

    1. This is one of those situations where so much depends on the temperament of the individual dog in question. However, my experience would suggest that anxiety related aggression is fairly common in GSDs, and the research backs up what I’ve seen in practice – neutering a happy dog leaves you with a happy dog, but neutering an anxious dog often leaves you with a really fearful one. I think your work with positive reinforcement is a really good approach, but I agree, at the moment the evidence would suggest that neutering him carries a marked risk of making it worse. I’m not a behaviourist, but that’s been my experience; it might be an option to ask your vet for a referral to a qualified canine clinical behaviourist – they might have some more ideas for things you can try? Good luck with him!

  31. My sister just adopted a 3 1/2 year old Intact male Border Collie about 2 weeks ago. He has acclimated really well into her family and their routine. He has not shown any aggressive tendencies whatsoever. If anything, he may be lacking in confidence. He is deferential (maybe even a bit scared) of the cats. He loves to play with other dogs (only humps one specific dog friend and dog friend allows it up to a point). Interaction with other dogs is appropriate and he reads their signals pretty well. He tends to avoid conflict and will walk away rather than engage if another dog becomes overwhelming. He came from a rural area and now lives in the suburbs so lots of things are new to him. He is curious and will go investigate new sounds and objects but quickly figures out they are nothing to be concerned with and walks away. When something does scare him, he goes to a person (usually my sister) for a quick moment of reassurance then goes about his business. He is scheduled to be neutered on about three weeks. I am a bit worried that neutering him will decrease his confidence and increase his anxiety.

    1. It’s possible it will, but if he’s fairly well balanced, it’s unlikely to make him really anxious. This is more of an issue with dogs who are already pretty nervous, and get much worse.

  32. We had our 1 year old border collie neutered 5 weeks ago and the change in him has been frightening. He spends a large amount of the day pacing around the dining room and cannot be distracted by food, toys or anything. He never did this before and would happily play with our 3 year old collie, but now he doesn’t even want to do that. We are putting it down to anxiety and have tried calm diffusers and sprays but have not seen any difference. He is so frantic when he is pacing that if you try and grab him to calm him down I am worried he will bite us. It seems to be any noise that sets him off, just someone being in the room and he starts pacing. I can’t get a vets appointment for 2 weeks and I just don’t know how we will cope until then. I’m worried about him but also the affect it is having on our other dog.

    1. Try to get hold of your vet on the phone and ask for an emergency referral to a clinical behaviourist – this sounds like something that needs addressing as soon as possible. Anxiety in collies is common, but this is definitely more serious than most.

  33. My son’s 18 month old Labrador was neutered 5 weeks ago, due to his interest in females! He was a well- adjusted confident dog before the op, but has now turned into a whimp, where he is frightened of my little terrier, who he has known and happily played with since he was born. She can’t understand why he doesn’t want to play anymore or why he runs away and hides. He visibly shakes at the sight of her. He also went full on attack mode at a German Shepherd while out walking, a dog he is well used to meeting. What has caused this change in behaviour, and how can it be resolved?

    1. There are a number of possibilities. It would be quite unusual for the fall in testosterone to change his behaviour this quickly – it usually takes longer – but it definitely isn’t impossible. I would be more suspicious of discomfort post-operatively that’s had the effect of making him anxious and uncomfortable. However, the good news is that behavioural issues like this can often be managed and even resolved very effectively, whatever the cause.
      The first thing to do is to get him checked over by your son’s vet to make sure that there isn’t any underlying medical issue (such as a low grade grumbling post-operative infection). The next step is to talk to a good canine clinical behaviourist – your vets will be able to recommend one – to address his anxiety. In the meantime, a lot of people (including myself!) have had great results with Adaptil diffusers or collars at managing low-level anxiety, and that’s definitely something I’d advise, although it can take several weeks to reach its maximum effect.

  34. I have a 3.5 year old Parson male terrier (Intact) and another female labradoodle, same age and neutered. I have delayed neutering as the parson is rather nervous. He obviously lunges and is slightly aggressive and suspicious of strangers and new dogs. I have done several training sessions to correct the behaviors which seems to be working. Still work in progress. I was thinking of having neutered now. Main reason was how he is the alpha to the labradoodle who fights back but sometimes look depressed at the unwanted attention. But I am still concern that it may make his aggression worse. Appreciate any thoughts and advice.

    1. Aggression caused by fear is more likely to be worsened by neutering; however, be very very cautious about using terms like “alpha” – dogs do not have strict hierarchies like captive wolves, and dominance based models of canine behaviour usually result in misunderstanding of their actions and massive welfare issues for them.
      However – personally, while there’s a behavioural issue ongoing, I wouldn’t be inclined to neuter unless your vet or a good clinical behaviourist recommend it.

  35. We have an appointment to have our 2 year old male cockapoo neutered this Friday. I have been back and forth on this for the past 3 months while waiting for the appointment. It’s now 4 days away and I am still undecided and looking for advice.
    We got Boomer at 7 months old, not at all trained, many bad habits including excessive humping, he was locked in his crate pretty much 24/7 with little attention. He made huge progress since and turned into a nearly perfect dog. He was never aggressive, his humping became limited to his dedicated pillow and only once in a while, he loves attention, loves socializing with people and other dogs, and is completely trustworthy when off leash. About 3 months ago he was attacked by a male dog and ever since has became slightly aggressive towards other male dogs. I.e if they get too close and sniffy he will growl and bark (behaviour we’ve never seen before). In addition his humping came back, he will now hump other male dogs at a dog park (will usually pick one and go after it) and once again will snap at other dogs that don’t respect his new boundaries. I’ve noticed other male dogs pursuing him and getting aggressive towards him as well now.
    We made the decision to neuter him in hope that it will reduce this behaviour and will allow him to enjoy socializing again without getting into trouble. But I’m struggling to figure out whether this behaviour is fear based or dominance based and whether neutering will help him or make it worse. Should i give my dog more time to readjust and myself more time observe his behaviour before making this call? I’m really worried that this is fear based behavior that will only get worse after the surgery. Thank you in advance.

    1. It might be best to discuss this with your vet – or a qualified canine behaviourist, who will be able to tell you what the likely causes of the behaviour are. Another option would be to talk to your vet about the neutering implant, that will wear off after a while but which duplicates the effects of castration. If he is better on the implant, castration can follow, but if he gets worse, then you don’t need to.

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