The RSPCA’s dog neutering guidelines on the latest studies on the effects of neutering and spaying on health and behaviour.
Six months in bitches who are likely to be over 20kg when full grown
Four months in bitches under 20kg when full grown
Seven months in male dogs.
However it is important to discuss with your vet and a qualified behaviourist, when the most appropriate time for neutering would be for each individual.
There is also evidence to suggest that for anxious or fearful male dogs neutering may make their behaviour worse. For these dogs it is essential to discuss the right time to neuter with your vet or a qualified behaviourist.