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What Is The Best Age To Neuter Jack Russell Terriers

Updated July 28, 2022

Whether you call it neuter, spay, castrate or desex, the right time to get it done in dogs is a subject of much debate. This is because it varies from breed to breed. Recently, a study was published on the best age for neutering in Jack Russell Terriers.

While the paper isn’t perfect (more on that later), it does provide the first evidence for Jack Russell Terriers on choosing a time of desexing with the fewest health problems. The study compared dogs neutered at different ages for their rates of:

All of these have been suspected to be linked with the age of neutering. Here’s what they found (only bold values are significant, my summary to follow):

HDCCLEDAt Least One
Male < 6 months0/14 (0)0/13 (0)0/14 (0)0/13 (0)
Male 6 – 11 months0/28 (0)0/27 (0)0/28 (0)0/27 (0)
Male 1 year0/12 (0)0/12 (0)0/12 (0)0/12 (0)
Male 2 – 8 years0/32 (0)1/32 (3.13)0/32 (0)1/32 (3.13)
Male Intact0/92 (0)0/91 (0)0/92 (0)0/91 (0)
Female < 6 months0/17 (0)0/17 (0)0/18 (0)0/16 (0)
Female 6 – 11 months0/43 (0)1/43 (2.33)0/43 (0)1/43 (2.33)
Female 1 year0/16 (0)0/16 (0)0/16 (0)0/16 (0)
Female 2 – 8 years0/34 (0)0/34 (0)0/34 (0)0/34 (0)
Female Intact1/84 (1.19)1/84 (1.19)0/84 (0)2/84 (2.38)
Joint disorders. For ages 1 through 11 years and for each neuter period: no significant findings.
LSAMCTHSAOSAAt Least One
Male < 6 months0/14 (0)1/14 (7.14)0/14 (0)0/14 (0)1/14 (7.14)
Male 6 – 11 months2/28 (7.14)0/27 (0)0/27 (0)0/28 (0)2/26 (7.69)
Male 1 year0/12 (0)0/12 (0)1/12 (8.33)0/12 (0)1/12 (8.33)
Male 2 – 8 years1/32 (3.13)1/31 (3.23)0/32 (0)0/32 (0)2/31 (6.45)
Male Intact0/92 (0)3/93 (3.23)1/92 (1.09)0/92 (0)3/93 (3.23)
Female < 6 months0/17 (0)0/18 (0)0/18 (0)0/18 (0)0/17 (0)
Female 6 – 11 months0/41 (0)1/43 (2.33)1/43 (2.33)0/43 (0)2/41 (4.88)
Female 1 year0/16 (0)0/16 (0)0/15 (0)0/16 (0)0/15 (0)
Female 2 – 8 years0/33 (0)2/34 (5.88)0/34 (0)0/34 (0)2/33 (6.06)
Female Intact0/83 (0)0/84 (0)0/84 (0)0/84 (0)0/83 (0)
Cancers. For ages 1 through 11 years and for each neuter period: no significant findings.

UI was not reported in any of the spayed or intact females.

If this table makes no sense, it’s mostly because there are no abnormal findings. Have a look at this one for Golden retrievers as a comparison. 

Summary: The Best Jack Russell Spay & Neuter Times

There is minimal evidence that Jack Russell Terrier health problems are influenced by the age of neutering. Owners of either sex are therefore free to choose the age of desexing that suits them best.

Recommendation: 6 months of age for both sexes.

This is so far the only science we have for the best desexing age in Jack Russells. Your vet, breeder or online group may have a different opinion based on their experience or personal beliefs. It’s perfectly reasonable to take their advice into consideration as well.

Problems With This Study

The authors do not mention the well-known increase in lifespan associated with desexing male and female dogs, which tends to counteract most concerns about specific cancers. The following comment in the paper is a clue that it might also have been true for this population:

Across all breeds the mean age of last entry in the record for neutered males was 5.5 years (range 3.71–6.54), for neutered females 5.7 years (range 4.21–6.97), for intact males 4.9 (range 4.15–7.11), and intact females 4.7 (range 3.41–6.32)

The study tries to also look at the rates of mammary cancer & pyometra in females, but cannot give an accurate assessment for two reasons:

  1. the mean ages listed above are far too young to pick up most cases
  2. pyometra and mammary cancer are rarely referred to university hospitals

Regardless of any concerns, the authors are to be applauded to bringing into focus one of the most common questions from dog owners. For the Jack Russell Terrier at least, they’ve made the decision a lot easier.

Related: Best Desexing Age For 35 Breeds | Desexing Choices For Dogs | Costs Of Desexing

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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. Meet his team here.

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