I have always (and only) heard that it is best to have the spay done before the pups first heat cycle. I have never heard or read anything contrary to this.....I would be interested to know how it would be better for the growth & development of the pup to wait
Where did you read this...is there a link you could post about it?
Going by the "spay before first heat" ........ any dog I've ever had or known and were spayed during that time frame all grew up healthy and well, so I guess I'd vote to stick with that route until proven otherwise.