In recent years there’s been a lot of debate as to what the risks and benefits are from neutering. This is especially true of larger breed dogs, and how best to manage them is a perennial debate. The benefits of neutering are pretty obvious, but some of the risks are subtle and harder to study. This week, new research has added more weight to the argument that neutering earlier can increase the risk of some joint problems, in some dogs.

What’s the news?

Researchers at the University of California’s Davis School of Veterinary Medicine have gone back over the records of 50,000 dogs, seen over 20 years. Their conclusions, just published, are that some joint diseases are more common following earlier neutering (before 1 year of age).

The joint diseases that seem to be influenced by neutering are cranial cruciate ligament injuries, hip dysplasia and elbow dysplasia.

Specifically, this association is only in medium- and large breed dogs (over 20kg adult weight). The researchers found there were no increased risks in smaller breeds.

How is it possible that neutering could affect these diseases?

That’s actually a good question, and on the surface, it does look unlikely. After all, we tend to think of ligament tears as being accidental injuries. It’s also very well established that Hip and Elbow Dysplasia are genetic conditions.

However, sex hormones have a massive impact on the development of the skeletal system. Think of growth spurts in puberty, for example. And these conditions are all associated with suboptimal bone alignment in joints, resulting in unusual wear or movement of the joint. So, it’s perfectly reasonable that by preventing the dog’s normal puberty from completing, we are altering the way these joints form. In a smaller dog, with smaller joints, the mismatch isn’t enough to cause a problem. However, in a large breed dog, it can cause disease.

Why is it important?

For many years, it’s been increasingly obvious that the neutering has far more subtle effects than many think. There is in our culture a tendency to think something is either “good” or “bad”, with nothing in between… but this is completely untrue when it comes to complex organisms like cats and dogs. And there’s nothing quite as nuanced as the neutering debate. Not just whether to neuter, but when to do so has been hotly debated. This news will add a little bit more evidence to the argument that says “wait”.

Wouldn’t we be better off not neutering at all?

Not necessarily. Firstly, there’s the problem of unwanted litters of puppies. Unwanted puppies are a massive welfare problem in some parts of the world. It’s also still perfectly true that neutering does prevent many health problems. these include pyometra and mammary tumours in female dogs, and prostate disease and perianal cancers in males. It can also make management much easier, and seems to dramatically reduce the risk of road traffic accidents (caused by roaming) in male dogs. However, we must acknowledge that there are downsides as well, including joint disease, but also an increase in some cancers. Many of the risks seem to be breed-specific, though, so this is another really good reason to treat each dog as a unique individual!

We’ll be looking at this in much more detail later this month with our “Neutering Week” – so watch this space!


Neutering of medium- and large-breed dogs (over 20kg) before the age of 1 year increases the risk of three different joint diseases. However, there is no increased risk for smaller dogs. However, not neutering at all increases the risks of other serious health problems, so the decision to neuter – and when – should generally be based on the individual risks and benefits for the specific dog in front of us.