[gemy]

Toy breeds can come in early to heat at say 6mths, but more often anytime after 8 mths old.

For any dog I recommend waiting until the growth plates close, and for females that usually means at least one heat has passed, as growth plates close in small breed dogs anywhere from 8mths to after one year old. There is no guess work; just have a lateral view of the tibia done, this is the last growth plate to close; if it hasn't closed then wait longer before spaying.

This delay at least gives you some time to see what baby teeth don't come out on their own, and for the tinies some time for a bit more weight gain.

As someone mentioned as a female dog owner you need to be vigilant to insure her safety through her first heat.