Spay and behaviour
26th May, 2020
Hormones affect our behaviour, dogs and humans, therefore it stands to reason that removing hormones will affect behaviour too. Spaying female dogs that become irritable pre season or when experiencing pseudo pregnancy will prevent further directly associated behaviour changes but it won’t reduce aggression between bitches showing aggression at other times. Because pseudo pregnancy isn't always associated with obvious physical signs, timing must be considered.
Aggression between two entire bitches in the home often begins when one or both reach puberty. Spaying both of them before puberty may reduce the risk of aggression but there is no guarantee.
The neutering experience can be extremely traumatic and it really helps to acclimatise a dog to the vets pre-spay by visiting for a fun time and not being examined. In addition, giving pre-med on arrival, allowing the owner to stay until the dog is drowsy and taking in a familiar blanket or toy will all help. If a dog is already fearful of strangers or is already scared of the vet, then it is best to deal with their fearfulness rather than potentially making this worse by neutering them.
Hormone changes after neutering can also increase fearfulness, the rise in levels of FSH and LH in both dogs and bitches is associated with increased reactivity. This generally reduces with time, however, bitches can experience surges of these hormones when they would have had their season. In some bitches spaying can precipitate pseudo pregnancy which can lead to increased fear and anxiety.
Several studies (O’Farrell and Peachey 1990 and Kim et al 2006) have reported increases in reactivity post spay. This may reflect increases in FSH, LH and prolactin mentioned above. It could also reflect the loss of the calming effect of Progesterone. There may also be other effects associated with the loss of oestrogen and progesterone because of their interactions with other hormones and neurotransmitters.
Spaying bitches pre puberty is likely to have beneficial and adverse behavioural effects. It will reduce likelihood of sexually dimorphic behaviours but it won’t necessarily prevent them. In other species, including humans, sex hormones have been shown to play an important role in the development of normal social interaction during adolescence (Schulz 2009).