Verified by 
"Behavioural problems in male dogs may be affected by how early in their life they are desexed, according to a study published today in PLOS ONE. The study even raises questions about whether we should encourage the routine desexing of male dogs at all."
I'm neither a dog trainer/teacher nor a veterinarian, but I for many years I've shared my home with numerous different dogs and also write a good deal about various aspects of dog behavior and dog-human interactions. While my primary expertise is on dog behavior, people commonly ask me questions about training and the behavioral effects of "fixing" dogs, especially males. I'm always extremely cautious about giving advice in either area and recommend that people find highly qualified and certified dog trainers and veterinarians where they live to deal with these queries. I also always say that dogs display marked individual differences in behavior and personality, and that there is no being whom we can reliably call "the dog."
Last week someone sent me a popular essay by the well-known Australian veterinarian and author Paul McGreevy and his colleagues called "Why decisions to desex male dogs just got more complicated." The title of this piece caught my eye because no matter how hard I've tried to make sense of when male dogs should be castrated and even if it's a good idea to routinely desex them, I've ever been able to come up with a reliable answer. Dr. McGreevy's popular essay and the research paper on which this piece is based by him and some colleagues called "Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may complicate population-control benefits of desexing" are both available online, so here I just want to direct interested readers to these essays.
What we basically learn in both pieces is, "Behavioural problems in male dogs may be affected by how early in their life they are desexed, according to a study published today in PLOS ONE. The study even raises questions about whether we should encourage the routine desexing of male dogs at all." So, when humans want to reduce roaming, mounting, and aggression, desexing is not a quick fix cure-all. Indeed, a previous study showed that desexing make and female dogs of different ages didn't have any effect on aggressive behavior toward familiar or unfamiliar people. The researchers involved in this study concluded, "Given the increasing evidence of significant negative health effects of gonadectomy, there is an urgent need to systematically examine other means of preventing unwanted procreation, such as vasectomy and hysterectomy."
Dr. McGreevy and his colleagues agree with this cautionary statement. They learned that male dogs who were castrated later in life peed more indoors and howled more when they were left alone than dogs who were desexed earlier in life. However, later desexed dogs showed a decreased in problem behaviors including "barking persistently when alarmed or excited, and showing signs of fear and anxiety in response to sudden or loud noises (vacuum cleaners and thunderstorms etc.)."
What are humans supposed to do about desexing dogs amidst prevailing myths that it's a cure-all?
Because dogs mature more naturally when sex hormones are allowed to work, timing of desexing is important to consider. Dr. McGreevy and his colleagues refer to an earlier study that showed "entire [intact, non-castrated] dogs of both sexes are bolder than desexed dogs, and that boldness decreases with aging...If boldness predicts less fearful behaviour and more sociable behaviour with humans and dogs, it would be desirable in companion dogs."
This is all well and good, however, what struck a more meaningful chord with me was that this team of researchers, along with others, still remain uncertain if desexing is worth doing, and from what I can glean from what they write, it surely shouldn't be a routine decision because it will solve any or many behavioral problems. To wit, Dr. McGreevy and his colleagues write, "The current findings present a paradox. Desexing may reduce the numbers of unwanted dogs at large. But it may also increase the likelihood of problem behaviours that reduce the appeal of the desexed dogs and make them more vulnerable to being surrendered." They are not saying that previous research about desexing has been wrong, but rather, deciding whether or not to castrate a dog really is a complex decision-making process and many factors need to be taken into account.
"My goodness, I fixed him to get him to stop humping or growling and being assertive and he still does it."
While I was writing Canine Confidential: Why Dogs Do What They Do, I carefully listened to people talking with one another at various dog parks about desexing and commonly heard something like, "My goodness, I fixed him to get him to stop humping or growling and being assertive and he still does it." Many people were very frustrated and a few told me that they were "sort of guaranteed" that desexing would fix the problems at hand. I wish their veterinarians were more familiar with what we know and don't know about desexing.
My non-veterinarian summary of what we know and don't know about the effects of desexing male (and likely female) dogs of any age is each and every dog must be looked at as an individual, and of equal importance, their relationship with their humans(s) also needs to be carefully assessed. People who choose to share their homes and hearts with a dog(s) need to learn about dog behavior and become "fluent in dog." Veterinarians can also play a major role in encouraging humans to learn about the behavior of the dogs or other companions with whom they've chosen to live.
While it's true that desexing can reduce the number of unwanted dogs, it's not a quick fix that will make everything else just fine. And, it's up to each and every human to decide whether something that they don't particularly like is really all that problematic and that it warrants desexing. Desexing isn't simply "minor surgery," a phrase I've heard many times from people whose dog has been castrated. It might seem to be "minor" because it's annoyingly routine, but it's not something that should be written off as "not all that serious." The procedure and the results clearly are very serious to each and every individual dog.
That desexing is a cure-all is one of many myths surrounding dog behavior. Desexing is a very serious decision and I'm glad that there are researchers who are also practicing veterinarians who are paying close attention to the pros and cons of this rather routine practice. Nothing will be lost and much will be gained by paying attention to the reason why a human is even considering desexing in the first place.
