Puppy begins to mature sexually: male begins to lift leg, and female has first heat period anywhere from 6 - 12 months. (diamondsintheruff.com)
Puppy begins to mature sexually: male begins to lift leg, and female that have not been spayed will have first heat period anywhere from 6 - 12 months. (austindog.org)
The surgery is usually performed at 6 to 9 months of age, before the first heat period. (rimobilevet.com)