Should I Have My Labrador Neutered: the latest evidence

Neutering Labradors and other dogs is a topic which comes up regularly, in my email inbox, in the comments section of the website, and on the forum. Most often people ask “when should I have my dog neutered”.

I hear the question “Should I have my Labrador neutered” less often, but its an important one. And you may be surprised to learn that there are risks to neutering as well as benefits.

Regional differences in attitude to dog neutering

Whether or not you should neuter your dog, male or female, is a very personal decision, yet in many countries, the answer is often presumed in advance. In the USA and Australia, routine neutering is very much standard practice.

The American Society for the Prevention of Cruelty to Animals claims on their website that you will “gain medical and behavioral benefits by having your male dog neutered”. In most of Scandinavia neutering is not routinely practiced and in some parts it is actually illegal to neuter a dog without good reason.

Where I live in the UK,  while neutering is fairly common, it is by no means an inevitable outcome for all dogs, and many dogs here are left entire. Americans visiting our forum and asking what is the best age to de-sex my dog, are often surprised to hear than many of our members have entire dogs. And even more surprised to have their assumption that neutering is best for their dog challenged.

Different opinions on neutering

Many people will tell you that there are health benefits to neutering your dog. And this is true. Many people will tell you that there are health benefits to leaving your dog entire.  And this is also true. Some people will tell you it is essential that you neuter your dog. This is not true. Others will tell you that it is essential that you do not neuter your dog. This also is not true.

Getting at the facts about neutering

It is a confusing topic and one that can generate quite strong feeling, with people being very convinced that their stance on neutering is the right one. And of course, it can be quite hard to hear others claiming that something you and all your friends have done, is actually harmful to dogs. So it is not surprising that this topic causes arguments online, and that the subject is often left unresolved, with everyone more muddled at the end than they were at the beginning

What those caring for puppies and young dogs need, is the facts about neutering. The evidence about what the likely effects of this procedure will be on their dogs. And because people often have a bias on this issue, evidence can be difficult to find.

Looking at dog neutering evidence

There have been some quite large studies recently that look at the effects of neutering on various aspects of dog health and behavior. What I would like to do in this article is ‘zero in’ on this evidence, so that we can compare the advantages and the disadvantage of neutering in a factual way.

We’ll be looking specifically at the effects of neutering on behavior and on physical health. You’ll find me using the word ‘may’ and ’might’ quite a bit, because I want to be objective. And not claim ‘this is so’ if we are not sure, or if we only know that ‘this is so’ in certain circumstances –  in one particular breed of dog for example.

At the end though, I will stick my neck out a little bit, and give you my own personal conclusions.

Reasons for neutering dogs

I think that it is important to look first at reasons for neutering. Because you need to know why you are neutering your dog, in order to ensure that the results you get are what you wanted. And of course, no-one wants to fork out for an expensive operation, or cut bits off their dogs for no good reason and with no benefit. We need to know if it works!

The four most common reasons given for neutering dogs are

• Birth control
• Health
• Behavior
• Convenience

Reason 1: Birth control

Preventing pregnancy is the reason most often given by members of the veterinary profession for the routine neutering of dogs. At one time when dogs roamed the streets unsupervised neutering was an important part of resolving the problems of dog over-population.

Most of the people that ask me about neutering however, do not leave their dogs free to roam the streets or countryside. Their dogs are kept in a secure backyard and exercised under supervision. This practice has become essential in densely populated countries, where the increasing volume of traffic over the last half century has made our streets far too hazardous for dogs to run free.

So, aside from convenience, which we’ll look at below, the most common reason that people chose to neuter their dogs is not because they are afraid their dog might mate or get pregnant. But because they believe that neutering will confer benefits to the dog (and his family) in terms of health and behavior.

Reason 2: Health benefits

If you are intending to neuter your dog in order to keep him or her in good health, it is pretty important that neutering will actually achieve this! And this is where the real controversy lies. Let’s look at why neutering was so widely recommended in the UK until recently.

Cancer in female dogs

For some time, neutering was widely promoted as a way of preventing dogs from getting cancer. Studies showed that neutering female dogs before the second season for example, greatly reduces their risk of getting mammary cancer. And early neutering, before the first season, almost eliminates that risk entirely. This made neutering seem like a very good idea.

More recently those studies have been called into question. But twenty years ago, almost all vets recommended neutering female dogs on this basis.

Pyometra

Then there is pyometra. I have personal experience of this horrible disease as two of my spaniels contracted it. Simply put, pyometra is an infection of the womb that around a quarter of all entire female dogs will get at some point in their lives.

The older the female dog, the greater the risk. And pyometra can be fatal if not treated promptly. There is no question that the risk of pyometra is almost completely avoided if your female dog is spayed. However public awareness of this condition is still not widespread so it is not necessarily a common reason for dog owners to chose to spay their female dogs.

Reason 3: Better behavior

So, that brings us to male dogs.  It stands to reason that a dog with no testicles, cannot get cancer of the testicles!

But the main reason that people neuter male dogs is not for the health benefits, though they usually believe there are some. It is because they believe that neutered male dogs are better behaved or have nicer manners than their oversexed hormone fuelled counterparts.  But is it true?

Concerns about male behavior

Here are some of the behaviors people worry about in mature entire male dogs

• Roaming
• Aggression
• Humping/mounting
• Marking/cocking leg

Neutering male dogs was believed to prevent or reduce a whole range of behaviors associated with or thought to be driven by, the hormone testosterone. Removing a dog’s testicles was presumed to be an excellent way of preventing these behaviors. However, recent studies suggest that these conclusions are not supported by evidence. We’ll have a look at those in a moment. Finally there is reason 4.

Reason 4: Convenience

Though not everyone is willing to put their hand up and say so, convenience is quite a common reason for neutering female dogs. It is definitely inconvenient when your entire, mature female dog comes into season. For three to four weeks you cannot walk her in public places, and she has a bloody vaginal discharge which will stain carpets and furniture. This usually means relegation to the kitchen or other rooms with washable floors.

Working dogs

When the dog has a job of work to do, dogs such as guide dogs for example, this inconvenience becomes life-altering for the dog’s carer. It basically means that the dog cannot do its job for a period of time. So for many service dogs, this consideration will over-ride any other concerns.

Dogs in day care

Some day care centres may stipulate whether or not they will take entire dogs. If you go out to work and have to leave your dog in day care, then this will be an important consideration for you.

There we have it. Four reasons to neuter a dog: birth control, health, behavior and convenience. Now let’s look at if neutering actually achieves what it is intended to do.

Is neutering effective?

Neutering clearly renders dogs infertile, so we don’t need to address the birth control aspect here. And there is no doubt that neutering removes the inconvenience of caring for a female dog in season. But what about the health, and behavioral benefits that lead so many people to neuter their dogs? Does neutering really protect dogs from the risk of serious illnesses like cancer, and does it really improve the behavior of male dogs?

Let’s look at some recent studies. These are studies on which veterinary professionals and informed dog owners are now relying in order to make decisions about neutering. First we need to quickly look at the question of how we can best evaluate the evidence we have.

Evaluating evidence

Some interesting studies have now been published which contain data on health and behavioral differences between neutered and entire dogs. These studies are beginning to influence expert opinion, in the UK at least, on the value and appropriateness of neutering our pets. I have picked four of these studies to discuss here.

There are other studies too, but I have chosen these four because they cover the largest sample of dogs. Large samples help to reduce the chances of the results being arrived at by coincidence. However, the size of a study is not the only aspect to consider when evaluating evidence. And these studies are by no means perfect.

The best evidence

In an ideal world we would be able to compare large numbers of dogs which would be randomly allocated to a ‘neutered’ or ‘not neutered’ groups. Dogs in the neutered group would be castrated at the same age and all the dogs in the trial would be assessed at intervals throughout their lives by someone impartial.

It would be even better if the observers making the assessments didn’t know which dogs were neutered. This could be achieved by cosmetic surgery on neutered dogs in the form of artificial testicle implants. However, realistically, this is simply not going to happen, so the evidence we do have is all we have at the moment.

Study no. 1

The first study is a summary of findings detailed in a Masters thesis submitted to and accepted by Hunter College by Parvene Farhoody in May, 2010. The research was carried out in the form of a questionaire which the owners of over ten thousand dogs filled in. The C-BARQ questionaire asked 101 questions aimed at looking at how neutering affected behavioral and physical characteristics of the dogs in the survey.

The results of the study were surprising because they showed that contrary to the prevailing view. Neutered dogs were more aggressive, fearful, excitable and less trainable, than dogs which had not been neutered. You can read the full study here:Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs (Canis familiaris)

Study no. 2

This was a study of over 2500 Hungarian Viszlas published in 2014, by Christine Zink et al. The study showed that dogs which were neutered had significantly increased odds of developing cancer. Including mast cell cancer, lymphoma, all other cancers, all cancers combined, and fear of storms, compared with the odds for sexually intact dogs.

Study no. 3

This next study is an older and smaller version of the first study. It was published in 2006 by Deborah L. Duffy, and James A. Serpell.  It also used the C-BARQ questionnaire. It found that urine marking was reduced in neutered dogs but like the 2010 study it found that most behavioral problems were worse rather than better in the dogs which had been neutered.

You can read the full study here: Non-reproductive Effects of Spaying and Neutering on Behavior in Dogs 

Study no. 4

This study published in 2013 included 759 Golden Retrievers. It looked at the effects of neutering on joint disorders and cancer. Hip dysplasia and cranial cruciate ligament tears were more common in early neutered males and females. As were several different forms of cancer. For example, almost 10 percent of early-neutered males were diagnosed with lymphosarcoma, 3 times more than intact males.  You can find the abstract for this study here

Another study comparing Labradors with Golden Retrievers found that the effects of neutering in Labradors were not as severe. For example in Labradors joint disorders were doubled in dogs neutered before six months old. Whereas in Golden Retrievers there were 4-5 times more joint disorders in the early neutered group

Potential flaws in these studies

With retrospective studies and studies where data is accumulated through questionnaires there is always scope for bias. It could be argued for example that owners of entire dogs are more likely to ‘play down’ their dog’s behavioral problems in order to justify leaving their dogs entire. And it is clear that there are differences between different breeds of dog

However, what we do not have here, is any evidence at all to support the view that neutering male dogs improves their general behavior or health. So what can we conclude from all this? Here is my summary, based on the available evidence so far.

Effects of neutering on female dogs

Neutering your female dog is will prevent her from getting pyometra which is very common, but curable if treated promptly. Neutering may also make your female dog susceptible to a number of different forms of cancer, which may not be curable.  It may also make her more prone to orthopaedic problems.

Neutering your female dog will also mean you are free from the inconvenience of twice yearly seasons. This could be a major factor to you especially if you work, rely on,  or compete with your dog.

Summary – male dogs

Neutering your male dog may make him more susceptible to number of different forms of cancer, which may not be curable.  It may also make him more prone to orthopaedic problems. Neutering your male dog will probably not improve his behavior and may make it worse.

A personal view

My personal feeling is that the adverse effects of neutering male dogs outweigh the benefits. With female dogs the situation is a little less clear.

I have had one of my spaniels spayed to protect her from pyometra, but in the light of the latest evidence, I have decided not to do this with my Labradors. My logic is that I can closely observe my female dogs for the weeks following each season and that pyometra, if it happens, can be treated effectively. Whereas hemangiosarcoma and lymphoma are less likely to be curable.

There are no easy answers here. What is right for one family, or one dog, may not be right for another. What is important is that you know why you want to neuter your dog, and that you know whether or not those aims are likely to be met through neutering. And it is likely that more studies and more information will arise over the coming years that will hopefully throw more light on this complex issue.

How about you?

Did you have your dog neutered?  And are you happy with the results?  Share your thoughts in the comments box below.  Or join in the conversation on the forum.

Readers Also Liked

• Complete Guide to Pyrometra

References and Resources

• ASPCA
• Korneliussen, I. ‘Should Dogs be Neutered?‘, Science Norway (2011)
• Farhoody, P. & Zink, M. (et al), ‘Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs (Canis Familiaris)‘
• Zink, M. (et al), ‘Evaluation of the Risk and Age of Onset of Cancer and Behavioral Disorders in Gonadectomized Vizslas‘, Journal of the American Veterinary Medical Association (2014)
• Duffy, D. & Serpell, J. ‘Non-Reproductive Effects of Spaying and Neutering on Behavior in Dogs‘
• Hart, B. (et al), ‘Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers‘, Plos One (2014)