I hear that some people get advised to neuter their dog already at the age of 12 weeks; but my advice, even though I am not a veterinarian, is to wait with your little girl or boy until it reaches the age of 6-10 months, pending on the individual development, body weight, and over-all stamina of your puppy.
The hormones our dogs produce are in every aspect necessary for their development.
Here are some case- scenarios I came across, or heard of, when the little puppy girl, or boy was neutered before being sexual mature:
- Girls (bitches) may "dribble" constantly at a later age, because the urethra did not have a chance to develop properly, and the appropriate muscles are not able to control the urine.
- Boys (dogs) tend to grow too much leg than they should, their chest may stay narrow, under-developed. And they may have problems with urinary stones because their urethra is also underdeveloped, hence not large enough.