Best Age to Neuter a Male Dog

The effects of neutering a dog too early changed the recommendation of when to neuter.


The best age to neuter a male dog has changed over the years. We used to think 6 months of age was just right. Turns out this may not have been the best idea, especially for large breed dogs. Historically, 6 months seemed reasonable as pups are done with their puppy shots by then, and they are at a nice, manageable size for surgery. It all seemed to make sense, but now we know a lot more.

Most veterinarians now recommend waiting to neuter male dogs after they reach full skeletal maturity, especially large breed males. Allowing these dogs to grow under the influence of their sex hormones means they grow more naturally, resulting in healthier joint angles and structure. They also grow stronger and less injury-prone tendons and ligaments. We have scientific proof that neutering a dog too early potentially makes him more prone to orthopedic problems like hip dysplasia and torn cruciate ligaments in the knee.

Waiting for skeletal maturity sets up new age recommendations for neutering:

  • Small breed dogs: after 12 months of age
  • Medium to large breed dogs: after 18 months of age
  • Giant breed dogs: after 24 months of age

Some veterinary specialists contend that we shouldn’t neuter male dogs at all. Those of us who still support neutering male dogs are quick to point out the benefits of neutering, including pet population control and the prevention of testicular cancer, prostatic disease, tumors growing on or around the anus (perianal adenomas), and perineal hernias (breakdown of tissue surrounding the rectum). All these diseases are preventable by neutering your dog before he reaches middle age. That said, aggressive, intact male dogs should always be neutered, as testosterone has been linked to aggression. Removing the source of testosterone helps manage this dangerous behavior issue.


  1. Our first GSD was neutered at 6 months in the mid 90’s, he had only one descended testicle so it was thought best to neuter him ASAP. He grew to about 95 lbs and tore his rear cruciate ligament at age 4. It was so sad to have such a wonderful and gorgeous dog go through that. We now know to never neuter that young, we wait until 2-3 years.

  2. This is definitely something that makes me very concerned and confused. I am an adamant supporter of adoption. I do not want to buy a dog when there are so many in shelters. But what does someone in my position do in regard to this topic? For the next male dog we will adopt. Which hopefully is a long time from now. Our male dog is now 6. He was neutered at about 8-9 mos. I do think that we will have an issue in the future. At his next physical I am going to request x rays of hips and knees. He does look funny sometimes when he runs. He is a medium size breed.

    I have not come across anything that tells someone how to mitigate this issue if the neutering was done an earlier age and there are potential issues brewing. Maybe another article for WDJ?

    • I start any dog I adopt on glucosamine/chondroitin. My female that was about 6 months when I got her (roadside drop-off) wasn’t spayed until after her first heat. I put her on the supplement when she was about 7 years and she lived to 15 with no joint issues at all. My current adoptee was neutered when he was about 5-6 years old and is on Cosequin right now.

    • As the director of a shelter that alters all pups over 12 weeks, we also recognize that there are some owners that are educated and concerned about this. I’d say 1% of our adopters ask about this and for those that do, and can cite the reasons why, we always make an effort to work with them. I’d suggest talking to the shelter when you’re ready to adopt again. We really do love the animals in our care and want what is best for them. But for the majority of adopters we need to release altered dogs….

  3. Years ago I had a Lab that was neutered at 9 months and tore his rear cruciate ligament a few years later, necessitating a TPLO surgery. Since then, I have neutered my males after they are 2 years old, and spayed my females after they have had 2 heats. All have been healthy with no structural issues, which is important when having an active life or doing dog sports. How about stating what the current guidelines are for spaying females?

    • The risk of breast cancer is quite high in unspayed females and rises with each heat cycle. The risk for a bitch neutered before the first cycle is only 0.05%, after the first cycle 8%, and after the second cycle 26%. Since the connection between ACL injury and early spays is not well established, less common than breast cancer, and more treatable, my next female will be spayed at 6-8 months. My current male is 3.5 years old and still intact; with impeccable behavior (he really is the goodest boy ever!) and temperament.

  4. Really happy to see this article on a topic we’ve recently been considering. Please consider a followup specific discussion of current options to standard surgical neutering (gonadectomy or castration) with pros and cons for the other options such as chemical sterilization, vasectomy, birth control, etc. Information, and vets who are not on autopilot, have been hard to come by. Thanks again for the thoughtful piece on an important topic. timing.

  5. I’m curious to see the study or studies on testosterone and aggression mentioned at the end of the article – where it noted that aggressive dogs should be neutered due tobehaviour. Can you please cite your source/s?

    I’ve worked with a few vet behaviourist in my time and they have said it has no effect but lots of vets still give this as a reason to neuter.

    McGreevy et Al 2018 did a study here in Australia a few years go that said that 24 common dog problems were significantly reduced with longer PLGH, 8 of which related to fear and 7 to aggression so we know that not desexing early has behaviour benefits, but I’d love to read about the studies on neutering to desex.

    • I agree. Behaviour such as aggression needs unpacking in much more detail ( than in my opinion – simply relating it to testosterone). In particular fear, anxiety, stress …which we know causes reactive and potentially aggressive type behaviours. I wouldn’t automatically recommend deserving a male dog with aggression without knowing a full history amd working with a behaviour vet.

  6. My female LGD was spayed at a very young age and at 6 and 7 years of age required TPLO surgeries for torn Cruciate Ligaments. It was not until later I learned if she was spayed later (after one litter or first heat) there was a good chance she would not have had to go through the surgeries. I now have a male LGD and he will remain intact until he is at last 24 months old. He did go through growth spurts but now at 18 months his muscle and bone growth has slowed to a manageable rate for him. If he shows aggressive tendencies then the decision to have him neutered will be made

  7. Very pleased to see this information finally get wider attention.

    How long will it take to trickle down to rescues and shelters, not to mention Vets at large?

    Guess I shouldn’t hold my breath waiting for the Karen’s of the world though. Lol

  8. I’m pleased there are now medical studies to back this up but it doesn’t solve my problem.

    My dogs are rescues and they don’t adopt them out without spaying. Both Diana pawPrints and Dolly (females) were spayed at 8 weeks. Diana is 92 lbs and I am dreading when she tears her cruciate ligament. Goliath and Caesar were private adoptions and they were neutered at 4 months because our local animal control requires it for licensing. Caesar was fine but Goliath had a problem with his hind cruciate ligament around age 6-8 years. The surgeon opted not to do the surgery and said it would heal on its own and he might have a bit of arthritis. Freyja wasn’t spayed until she was about a year old as she was picked up as a stray off the streets. Age is an estimate but Vet thinks she was around a year old, (shelter said two years old) so I’m hoping Freyja has avoided any of the problems early spaying might have caused.

    While this article regards males and the consequences I am going to assume that females spayed too early also are subject to medical issues, albeit possibly not the same ones. I was very careful with Diana’s diet and exercise as a puppy as I knew she would get big (although not quite this big) and wanted to make sure she was getting the right balance of fats, protein, etc and exercise to ensure healthy bones and joints. The one thing I could not control was her being spayed at 8 months and it has always bothered me.

    With this article I think for any future dogs I get, I will try to delay any procedures for at least a year, even if it means paying more for the initial dog license. If it means a longer, happier, healthier life, then it is a small price to pay.

  9. After suffering through diabetes with our beautiful Malamute mix, Dancer, (castrated at our vet’s strong recommendation ~4 yrs), we will never again choose castration. (See quote below.) We opted for vasectomy for Kerry, our 26# Mini Aussie, after discovering this research. (The breeder required sterilization.)

    It was traumatic for all of us as the vets at UC Davis insisted on shaving a large area including his balls (despite the tiny incisions) which became became irritated and itchy. Our formerly happy, trusting puppy was miserable, hated his cone and lost his faith in us. It took me several days to make a cone he couldn’t defeat and much, much longer to somewhat repair our relationship. He became chronically suspicious and intolerant of handling. Typical Aussie behavior? Perhaps. We give him 50mg of trazodone before going to the vet. That helps somewhat.

    Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may complicate population-control benefits of desexing
    Paul D. McGreevy , Bethany Wilson, Melissa J. Starling, James A. Serpell

    “Some health benefits of gonadectomy may be offset if it compromises health in other ways. For example, spaying female golden retrievers has been associated with a 3–4 fold increase in the rate of some cancers [19]. Same-breed castrated males showed only minor increases in risk of cancers. In another study, castrated males of many breeds had a higher risk of diabetes mellitus than entire males, whereas spaying was not associated with an increased risk in females [20]. Gonadectomy has also been associated with increased bone length [21], which may, in part, explain why studies focused on osteosarcoma found twice the prevalence in gonadectomised dogs than in entire dogs of several breeds [22] and an increase of 3–4 times in Rottweilers castrated before 1 year of age [23]. Similarly, studies of golden retrievers [24] and German shepherd dogs [25] have shown that early neutering can significantly increase the prevalence of joint disorders, such as hip dysplasia.”

    20. Mattin M, O’Neill D, Church D, McGreevy PD, Thomson PC, Brodbelt D (2014) An epidemiological study of diabetes mellitus in dogs attending first opinion practice in the UK. Veterinary Record 174:349. pmid:24570406

  10. How coincidental that I just had a long conversation a week before Christmas about the best time to neuter my now almost 10-month-old male Golden Retriever! I also have a female Golden who is six months (and one day) younger. We decided that the best way to decide when to neuter the male is to wait another 3-4 months and then do radiographs to see if his growth plates have closed yet. If so, then we’ll do the surgery at that point. If not, we’ll revisit the question of when. Meanwhile, if the female comes into season while we’re waiting, the male will spend a week or two at his breeder/my friend’s home while the female is ovulating. Once the female has had her season, we’ll talk again about the male’s surgery.

    By the way, what you say about the age at which to neuter a male of medium/large breed or giant breed conflicts slightly (by six months) with what my vet has told me. So, I’d like to know which study you’re going by. I totally trust my vet as I’ve known him for several years and have seen him go through some personal growth in that time. I know he would not tell me something that isn’t true just to make money off me.

  11. What do you say about shelters and rescues that adopt out puppies as young as 8 weeks old already neautered? I’m a staunch supporter of spay/neuter but also feel that this is waaay too young an age for this procedure. There must be an alternative to insure that these pups (and kittens) don’t become breeders, but surgery at such a young age shouldn’t be mandatory. Personally I don’t know what the answer is but I’m just expressing my feelings about subjecting these babies to a procedure that may affect their future health.

    • I agree with you 100%! My now deceased shelter pup was spayed at 3 months of age in 2012. In addition to behavioral issues, she developed a small hernia near the spay surgical site and in middle age started having hip joint issues. My dear girl left me last year, two days after her 10th birthday, from sudden cardiac arrest (which I believe was caused by chronic stress related to our dealing with my husband’s dementia). In any case, I think the answer to your question may be a shelter adoption contract which states that the animal must be spayed/neutered no later than at age two either by the shelter’s vet or a vet of the adopter’s choice with documented proof of said procedure.

    • Shelters and rescues can do an OSS (Ovary sparing spay) on 8 week old females. Removing the uterus prevents pregnancy and pyometra while preserving the hormones and allowing the puppies to develop properly. Owners can always go in an remove the ovaries later if they do not like the hormonal cycling. This to me is a no-brainer! OSS needs to become the standard.

  12. More vets are offering vasectomies and OSS (ovary sparing spay) as options for pet owners.
    Choosing the procedure satisfies their concerns for hormonal growth and potential health complications associated with early spay and neuter.
    Shelters could offer similar choices for adoptions as well.
    These options would prevent pregnancy while giving owners the right to choose which procedure is best for their pets.

  13. I’ve had a trainer and vet recommend neutering my 20-month-old Border Collie/Chow because of how *other* dogs react to him. They say other dogs will be calmer/less reactive with him once he’s fixed (unfixed dogs are rare around). I’ve heard from a few people that their male dogs were attacked frequently before they were neutered but were left alone after.

    This doesn’t seem like a great reason to neuter, does it?

  14. Finally. This has been known for years, and yet most veterinarians recommend neutering/spaying as soon possible. I understand the animal shelters have little choice due to unresponsible people – sad that the animals pay the price as usual for our incompetence.