Neutering male animals reduces aggression by removing testosterone production.

Is it true that Neutering male animals reduces aggression by removing testosterone production?

Partly. One reference work states neutering lowers hormone levels and reduces certain forms of male aggression in species other than dogs, while a veterinary review reports increased fear, anxiety and aggression in neutered male dogs and notes the castration-reduces-aggression belief rests on early studies. Other items find aggression not consistently tied to circulating testosterone, so the evidence covers the claim only in part and points both ways.

Verdict: CONTESTED PARTIAL · 1 source for, 3 against · Last checked 3 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Neutering. (n.d.). en.wikipedia.org. https://en.wikipedia.org/wiki/Neutering

Dog Neuter, Yes or No? A Summary of the Motivations, Benefits, and Harms, with Special Emphasis on the Behavioral Aspect - PMC Lock. (n.d.). pmc.ncbi.nlm.nih.gov. https://doi.org/10.3390/ani15071063

Is testosterone responsible for typically "male" behaviour?. (2013). skeptics.stackexchange.com. https://skeptics.stackexchange.com/questions/14355/is-testosterone-responsible-for-typically-male-behaviour

Lipshutz, S. & Rosvall, K. (2020). Nesting strategy shapes territorial aggression but not testosterone: a comparative approach in female and male birds. doi.org. https://doi.org/10.1101/2020.12.19.423623