What Is The Best Age To Neuter Large Breed Dogs

Updated October 18th, 2020

Whether you call it neuter, spay, castrate or desex, there’s been a lot of debate about the right time to get it done in dogs. That’s because it varies from breed to breed. Recently, a study was published on the best age for neutering large dog breeds.

The study actually looked at 30+ kg crossbreeds but this data should be the closest match to a large breed currently available if it isn’t in covered this list.

While the paper isn’t perfect (more on that later), it does provide the first evidence for large-sized dog breeds on choosing a time of desexing with the fewest health problems. The study compared the 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, after the four tables you will find my summary):

Dogs 30-39kg

HDCCLEDAt Least One
Male < 6 months2/41 (4.88)6/45 (13.33)0/43 (0)7/41 (17.07) †
Male 6 – 11 months2/38 (5.26)3/46 (6.52)0/45 (0)4/37 (10.81) †
Male 1 year1/50 (2)0/51 (0)1/51 (1.96)1/50 (2)
Male 2 – 8 years0/44 (0)0/46 (0)1/48 (2.08)1/45 (2.22)
Male Intact7/173 (4.05)5/177 (2.82)4/174 (2.3)13/174 (7.47)
Female < 6 months1/31 (3.23)3/32 (9.38)0/33 (0)3/30 (10) †
Female 6 – 11 months4/50 (8)8/48 (16.67)1/51 (1.96)11/47 (23.4) †
Female 1 year0/35 (0)1/37 (2.7)0/38 (0)1/34 (2.94)
Female 2 – 8 years0/50 (0)2/50 (4)0/51 (0)2/48 (4.17)
Female Intact0/55 (0)0/57 (0)0/57 (0)0/55 (0)
Joint Disorders. For ages 1 through 11 years and for each neuter period. Bold values indicate significance over the intact group. The dagger () indicates significance over the intact group when the early groups (< 6 mo. and 6-11 mo.) are combined.
LSAMCTHSAOSAAt Least One
Male < 6 months2/42 (4.76)0/43 (0)0/45 (0)0/45 (0)2/42 (4.76)
Male 6 – 11 months2/46 (4.35)0/44 (0)2/45 (4.44)0/46 (0)4/44 (9.09)
Male 1 year0/51 (0)1/51 (1.96)1/51 (1.96)1/51 (1.96)3/51 (5.88)
Male 2 – 8 years1/48 (2.08)1/47 (2.13)0/48 (0)0/48 (0)2/47 (4.26)
Male Intact13/175 (7.43)6/176 (3.41)1/174 (0.57)5/174 (2.87)25/172 (14.53)
Female < 6 months1/32 (3.13)2/33 (6.06)0/33 (0)1/33 (3.03)4/32 (12.5)
Female 6 – 11 months0/50 (0)2/50 (4)1/51 (1.96)0/50 (0)3/48 (6.25)
Female 1 year1/38 (2.63)1/37 (2.7)1/37 (2.7)0/38 (0)3/37 (8.11)
Female 2 – 8 years0/51 (0)2/52 (3.85)0/52 (0)1/52 (1.92)3/51 (5.88)
Female Intact5/56 (8.93)1/57 (1.75)0/56 (0)1/57 (1.75)7/55 (12.73)
Cancers. For ages 1 through 11 years and for each neuter period: no significant findings.

Dogs 40+ kg

HDCCLEDAt Least One
Male < 6 months2/17 (11.76)5/18 (27.78)0/18 (0)5/18 (27.78) †
Male 6 – 11 months1/27 (3.7)2/28 (7.14)0/27 (0)3/27 (11.11)* †
Male 1 year0/20 (0)1/19 (5.26)2/21 (9.52)2/19 (10.53)
Male 2 – 8 years0/36 (0)0/32 (0)0/36 (0)0/32 (0)
Male Intact1/86 (1.16)7/91 (7.69)0/86 (0)8/87 (9.2)
Female < 6 months1/11 (9.09)1/12 (8.33)0/11 (0)2/11 (18.18)
Female 6 – 11 months0/10 (0)0/12 (0)0/11 (0)0/10 (0)
Female 1 year0/4 (0)0/4 (0)0/4 (0)0/4 (0)
Female 2 – 8 years0/13 (0)0/13 (0)0/14 (0)0/13 (0)
Female Intact1/18 (5.56)3/18 (16.67)0/17 (0)3/18 (16.67)
Joint disorders. For ages 1 through 11 years and for each neuter period. Bold values indicate significance over intacts. Asterisk (*) shows significance using the Wilcoxon test: no significance with log-rank test. Dagger () indicates significance over intacts when the early groups are combined.
LSAMCTHSAOSAAt Least One
Male < 6 months1/18 (5.56)0/18 (0)0/17 (0)0/18 (0)1/17 (5.88)
Male 6 – 11 months1/28 (3.57)2/27 (7.41)0/27 (0)0/28 (0)3/27 (11.11)
Male 1 year0/20 (0)1/21 (4.76)2/21 (9.52)0/21 (0)2/21 (9.52)
Male 2 – 8 years1/36 (2.78)0/36 (0)0/34 (0)1/35 (2.86)2/33 (6.06)
Male Intact4/84 (4.76)0/88 (0)2/87 (2.3)2/84 (2.38)8/81 (9.88)
Female < 6 months1/12 (8.33)0/12 (0)0/12 (0)0/12 (0)1/12 (8.33)
Female 6 – 11 months0/12 (0)0/11 (0)0/11 (0)0/12 (0)0/10 (0)
Female 1 year0/4 (0)0/4 (0)0/4 (0)0/4 (0)0/4 (0)
Female 2 – 8 years1/14 (7.14)1/14 (7.14)0/14 (0)0/14 (0)2/14 (14.29)
Female Intact1/17 (5.88)0/17 (0)0/17 (0)0/17 (0)1/17 (5.88)
Cancers. For ages 1 through 11 years and for each neuter period: no significant findings.

UI was only documented in females spayed under 6 months of age.

Summary: The Best Large Dog Spay & Neuter Times

Joint problems were more common in large dogs desexed under 1 year of age.

Recommendation: 1 year for both males and females, but the decision may be based on other factors such as:

Problems With This Study

In the original paper, the authors appear to make some recommendations based on very limited evidence. I have published the original study data so you can see the actual numbers involved and decide for yourself.

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 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 large breed dogs, they’ve made the decision a lot easier.

Related: Best Desexing Age For 39 Breeds | Desexing Choices For Dogs | Costs Of Desexing

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!
Have something to add? Comments are welcome below and will appear within 24 hours.

Andrew

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