Sterilisation A Behaviourist Point of View

Sterilisation A Behaviourist Point of View

Dr Frederique Hurley , Behavivet

Castration of male dogs and cats has valuable behavioural benefits. Castration can decrease unacceptable sexual behaviour, aggressiveness, urine marking, and prevent breeding. With respect to behaviour, it should be clearly understood that the only behaviours affected by castration would be those that are influenced by male hormones. Thus, castration effects sexually dimorphic behaviours, those seen predominantly in males.

The undesirable behaviours that decrease with castration are1, 2, 4:

Undesirable sexual behaviour

  • Can reduce attraction to females, roaming, mounting and masturbation
  • Roaming in cats can be reduced in over 90% of cases and 70-80% of dogs have a reduction in roaming but only about 40% are completely resolved4
  • Mounting of other animals, people or inanimate objects in dogs is reduced in 70-80% of cases but resolved in only 25%


  • Marking with urine is a common territorial behaviour in dogs and cats
  • Castration reduces marking in about 70-80%of dogs but only about 40% are completely resolved. Marking by spraying urine is reduced in 90% of cats4


  • Intermale aggression can be reduced in about 60% of dogs and 90% in cats
  • Aggression towards family dogs and family members may be reduced in about 30% of dogs
  • Aggression toward unfamiliar dogs and intruders may be reduced in 10-20% of dogs

Since castration can help curtail roaming, castrated dogs and cats are less likely to be endangered by viral, bacterial, parasitic or environmental dangers.

Bitches and queens may show altered behaviours with oestrus, including increases in some forms of aggression, and bitches may show nesting and mothering behaviours and lactation with false pregnancies. Maternal aggression refers to aggressive behaviour directed toward people or other animals that approach the bitch with her puppies. Bitches that experience pseudocyesis (false pregnancies) may also display maternal aggression despite the lack of puppies. Sterilisation will prevent maternal aggression.

It must be kept in mind that there may be other reasons for the behaviours mentioned above. These should be diagnosed and treated. Therefore sterilisation is often an adjunct to behavioural modification, management, environmental enrichment, pheromone treatment, neutraceutical treatment and behavioural medication and it should not be thought that sterilisation will provide the ‘quick fix’ (excuse the pun) on its own.

The likelihood of a behavioural response to castration is not associated with the age at castration or duration of the behaviour prior to castration in male dogs or cats3. However, if the behaviour has been present for a longer duration, the benefit of sterilisation may decrease as the stimulus that started the behaviour may not be the same as the stimulus that maintains the behaviour. This implies that the current behaviour may not be driven by the sex hormones anymore.

Since animals may have a genetic predisposition for undesirable behaviour, sterilisation should be considered in animals displaying behaviour problems, if not to resolve the behaviour problem, then to prevent passing it to the offspring.


1. Beaver, B. 2009. Canine Behaviour insights and answers. 2nd Ed. Elsevier Saunders, Missouri

2. Bowen, J and Heath, S. 2005. Behaviour problems in Small Animals. Elsevier Saunders, Edinburgh.

3. Krustrutz, Root. 2012. Effects of Surgical Sterilization on Canine and Feline Health and on Society. Reproduction in Domestic Animals 47(Suppl. 4), 214-222

4. Landsberg, G; Huthausen, W and Ackerman, L. 2003. Handbook of Behaviour Problems of the dog and cat, 2nd Ed. Elsevier Sauders, Edinburgh.

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