When Is The Best Time To Spay Or Neuter My Jack Russell Terrier?

January 4, 2022
January 4, 2022

It’s hard to know when to spay or neuter – or if you should at all. Here’s the best veterinary advice for your Jack Russell Terrier.

So you’ve decided to spay or neuter your Jack Russell – but when is the right time?

Often called getting your dog Fixed or Done (nomenclature that bugs me, because, fixed, implies broken, which is kinda mean!), the majority of dogs have this minor procedure performed upon them at a young age. Usually on a veterinary recommendation.

I know when Indie was little, I was told: “Six months, on the dot” – which is common advice given across America and Europe. If you ask the Internet (i.e. Facebook) usually recommendations say later and often err towards a minimum of twelve months. 

But is that even right? Or is it founded in any sort of science? 

With this conflicting information, how are you meant to know? Trust your vet? Do as your family has always done? Or trust the rando on the internet who appears to know it all. 

None of that seems to be a good idea when the potential consequences of these procedures are rumoured to be some of the scariest diseases and ailments a dog can face… Cancer, Hip or Elbow Dysplasia, and other rotten afflictions like pyometra. All of this is the result of removing the availability of hormones…

Luckily, research has come forward which is not just size specific, but breed-specific for 35 breeds! So, here we’re going to discuss the ideal times for spaying or neutering your dog.

First, let’s do a little housekeeping…

Jack Russell Terrier running.  Spaying or neutering a Jack Russell Terrier is a big decision, it's best that they are responsibly bred.
Vigorous exercise like this is really not recommended straight after a spay or neuter surgery instead try Post-Surgery Recovery: 12 Ideas For Keeping Your Dog Happy And Entertained.

What is Neutering?

This is the surgical castration of a male dog – usually by the removal of his testicles (sorry for making you cringe, gents!). This process means that your male dog cannot breed and that they are no longer producing hormones that are important to your dogs’ development – both emotionally and physically.

What is Spaying?

Similar to neutering, spaying is a form of surgical castration that removes the ovaries and most often the fallopian tubes along with it. This means your girl cannot breed, but it also means she is missing some critical hormones.

This process can be done in a ‘keyhole’ surgery at extra cost, though it is much better for recovery times.

So when is the best time for my Jack Russell Terrier ?

Recommended age:

Male – It’s your choice!

Female – It’s your choice!

I was genuinely surprised to see that the Jack russell was such a small sample size here. In the UK, they’re quite a prominent breed, but here we have only 376 terriers to represent! Not the smallest sample by far, but still, small enough that it means across 10 groups, we’d average 37.6 terriers per group (actual numbers vary, but this is to give an indication!).

This is pretty small, and would only start really concerning me if we were looking at severe statistics or dramatic spikes, so let’s have a look at those, shall we?

Whilst neutering doesn't affect behaviour, neutering may affect your boys roaming to find females.
What a cutie! How can you resist that face! The age of your pup is really important as a factor in their future health as you consider spay or neuter surgery. If you need more info on the process, head over to The Rebarkable Spay & Neuter Information Center!

What Are The Risks?

Here’s a quick overview of what the study says the breed suffers from depending on when their surgical castration (Spay or Neuter) was performed. The aim of providing this information is about giving you all the information to make the best decision.

Disorders include – Cranial cruciate ligament tears or ruptures, Hip Dysplasia, Elbow Dysplasia 

Cancers include – LymphomaHemangiosarcomaMast Cell Tumours, Bone Cancer (Osteosarcoma),

GenderAge of
Surgical Castration
Disorder riskCancer Risk
MaleUnder 6 months0%7%
Male6 to 11 months0%8%
Male12 to 23 months0%8%
Male2 years to 8 years3%6%
FemaleUnder 6 months0%0%
Female6 to 11 months2%5%
Female12 to 23 months0%0%
Female2 years to 8 years0%6%
Comes from Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence (Hart et al, 2020) 376 Jack Russell Terriers were monitored over the course of 15 years to collect this data.
  • 1% of intact females developed Pyometra.
  • Urinary incontinence was 0% in spayed females.
  • Mamary cancer was witnessed in 1 % of intact females in those spayed at 2-9 years it went up to 3%

Personally, I’m rarely a big advocate of a pediatric (under 6 months) operation, so, my instinct would be to leave the boys intact and get your girls done in the 12 to 23 month window.

Cancer seems to be our big risk here that we would try to mitigate, it’s not easy, but it’s doable. Just remember cancer also has a genetic proportion too, so check with your breeder.

One thing that is worth noting (seen as they can be predisposed to reactivity) is that neutering will not affect ‘aggression’. Neutering will only effect marking and roaming in efforts to breed – if your dog is experiencing signs of reactivity – go sign up for Rebarkable Reactives on the Services page!! It’s well worth it.

jack russell terrier being good

Want a Terrific Terrier?

It can be so frustrating bringing home a
new puppy.
What if I told you I could give
you the magic formula to turn this
rambunctious puppy into a great dog?

Are there other options?

If you’re doing what I am doing and looking at this research and reconsidering? It’s good to know that there are other options available.

Yes! On the presumption that these issues are caused by the lack of hormones (which is almost certainly the issue!) – there are a couple of ways to keep hormones but not facilitate breeding.

For Girls


This is the surgical removal of the uterus and only part of the fallopian tubes! The removal of these means that your girl is without the ability to breed – however – as she keeps her ovaries, hormones will still be produced and should mean that her risk levels are the same as an intact female – without the risk of pyometra! Though, there is a risk that the breeding instinct can remain? Which may be quite risky if a male tries to breed with her. 

3 Jack Russell Terrier puppies socialising
Before and after a spay or neuter surgery, socialisation is so important for your Jack Russell Terrier

For Boys


The tubes that run from the testes are called the vas deferens – these are what get cut or removed in this instance – rendering your dog without the ability to impregnate a female. It leaves his hormones (and likely his desire to breed as a result) but also means that your dog should have the same risk factors as an entire male.

Chemical Castration

Did you know that surgical castration is not legal in Norway? Consequently what is common in Sweden, Denmark, and Norway is chemical castration which is an injection your dog will have to have every six months that drop the levels of testosterone by approximately half. Which is proven to be effective in temporary neuter for your dog. This means you can actually test what castration might do to your dog and is often how it’s used in the UK and America – but it’s also a fantastic way of not putting your dog through surgical procedures. 

About the Study

The study “Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence” (Hart BL, Hart LA, Thigpen AP, Willits NH) was released in July 2020 – it covers 35 different breeds – and a separate scientific paper for mixed breeds. The study followed a total of 15,414 dogs over 15 years of recording;

  1. The age of the dog when neutered or spayed
  2. Breed
  3. Disorders including: 
  4. Cancers including;

General Thoughts Across The Study

I find it incredibly interesting that there is breed-specific deviance. Prior to this, I was very much of the camp that it was simply a case of variations for dogs of different size brackets – but that appears not to be the case.

For example, a male Labrador (for whom I would have assumed were not dissimilar to Jack Russell Terrier) actually have the best results when neutered at 6 months – yet the females prefer a slightly older age (When Should I Spay Or Neuter My Labrador is here by the way!).

So it’s really worth doing your research about these things.

As always? There’s not quite enough information to make a totally informed decision (yay for variables!) but, you can definitely get a good idea of it.

Other Considerations

It is worth noting that this study is a fantastic guideline – and one of the most solid pieces of research we’ve had – it doesn’t take into account many factors that I would imagine should be considered. The limitations I see are as follows;

  • Multiple conditions were not recorded if they fell in the same category,
  • Genetics were not considered,
  • Living conditions were not considered,
  • Food quality was not considered,
  • The exercise a dog had was not considered,
  • Body condition was not factored in because it had been studied previously and no strong correlation was found between body condition and joint issues.

What do you think, Ali?

I’ve been asked before where I stand. I stand with logic and whatever is best for you and yours.

That, in itself is not something I can determine for you. You need to look at the facts, your dogs breed, your dogs temperament and any details you may have from their breeders family history. Then consider your situation. Will you be knowledgeable enough to prevent accidents from happening? Do you know what to do if accidents do happen?

These questions and lots, lots more are important. Because whilst I wholly support you in your decision to spay, neuter or not – we don’t need poorly bred puppies in this world. Puppyhood is such an important thing in our dogs, from how the bitch carries them to the first year of their life… it’s not something to get into lightly.

The biggest thing I can say is, that whilst this is the scientific recommendation for when to spay or neuter your Jack Russell Terrier do remember that at the end of the day? This is your decision. You are the only one who can make this decision. So, do your best – you’ve already found a phenomenal resource – just keep reading.

If you have any questions about spaying or neutering your Beagle, drop them in the comments below! Or check out The Rebarkable Spay & Neuter Information Center! Where you’ll find the answers to all your spay & neuter questions.

Author, Ali Smith

Ali Smith is the Positive Puppy Expert, dog trainer and is the founder of Rebarkable. She is passionate about helping puppy parents get things right, right from the start. To help create a puppy capable of being a confident and adaptable family member and keep puppies out of shelters.

Ali has won multiple awards for her dog training, and has had her blog (this blog!) rated as 2021 & 2022 worlds’ best pet blog!

Thanks to depositphotos.com for the images!


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