Spaying or neutering a dog can make the animal less aggressive.

the verdict

CONTESTED

contested - evenly split

Recorded sources

2 sources for · 2 against

Counts group repeated records of the same source within each side. They do not measure evidence strength or source independence.

Is it true that Spaying or neutering a dog can make the animal less aggressive?

Partly. While some studies indicate that spaying or neutering can reduce certain aggressive behaviors in dogs, other reviews and findings report conflicting results, noting that the procedure can occasionally be associated with increased fear or aggression.

Verdict: CONTESTED · 2 sources for, 2 against · Last checked 3 Oct 2026

The evidence we hold leans evenly split

How this was weighed

official record 3x · fact-check 2x · hedged 1x · crowd & reference 1x

Influence of Gonadectomy on Canine Behavior · peer-reviewed · supports · weight 1.3 · 2021
Reproductive Control in Dogs with Emphasis on Anti-GnRH Immu · peer-reviewed · supports · weight 1.05 · 2025
Dog Neuter, Yes or No? A Summary of the Motivations, Benefit · peer-reviewed · refutes · weight 1.05 · 2025
Exploring behavioral outcomes of gonadectomy in pets: a need · peer-reviewed · refutes · weight 1 · 2026

Evidence for · 2

Influence of Gonadectomy on Canine Behavior

2021

This study found a tendency to reduce owner-directed aggression in experimental male dogs following gonadectomy.

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Palestrini, C., Mazzola, S. M., Caione, B., Groppetti, D., Pecile, A. M., Minero, M., & Cannas, S. (2021). Influence of Gonadectomy on Canine Behavior. doi.org. https://doi.org/10.3390/ani11020553

Evidence against · 2

Dog Neuter, Yes or No? A Summary of the Motivations, Benefits, and Harms, with Special Emphasis on the Behavioral Aspect.

2025

This review highlights that conclusions on behavioral outcomes remain inconclusive, with some studies even suggesting increases in aggression following neutering.

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A, A. & AF, P. (2025). Dog Neuter, Yes or No? A Summary of the Motivations, Benefits, and Harms, with Special Emphasis on the Behavioral Aspect.. doi.org. https://doi.org/10.3390/ani15071063

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More for · 1

Reproductive Control in Dogs with Emphasis on Anti-GnRH Immunocastration and Its Behavioral Effects.

2025

This review notes that immunocastration and reproductive control can decrease behaviors such as roaming, aggression, and sexual mounting.

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MJ, U., M, L., D, S., & L, S. (2025). Reproductive Control in Dogs with Emphasis on Anti-GnRH Immunocastration and Its Behavioral Effects.. doi.org. https://doi.org/10.3390/vetsci13010005

More against · 1

Exploring behavioral outcomes of gonadectomy in pets: a need for personalized approaches.

2026

This article emphasizes that the effects of gonadectomy on behavior are contentious, noting that conflicting research suggests neutering may sometimes intensify aggression and anxiety.

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FB, G., RO, B., & M, A. (2026). Exploring behavioral outcomes of gonadectomy in pets: a need for personalized approaches.. doi.org. https://doi.org/10.1590/1984-3143-ar2025-0125

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