the only thing the spaying is doing is getting rid of the mess and the possibly of the unwanted accident of puppies.

The rule again is:

Spay before first heat - almost a zero percent chance of mammary cancer.

Spay after the first heat, and before the second- the chances are 7% relative to those spayed before the first heat for mammary cancer.

Spay after the 2nd heat or pregnancy - it's a 1 in 4 or 25% chance of mammary cancer later in life. The chances do not seem to get any worse (which are bad enough) after the second heat or pregnancy or subsequent heats.

If you Spay a female too early there is a greater chance of incontenance. The Vets were recommending any time after 3 months which I believed was too soon due to the possible problem of incontenance. Since my females have been larger breeds I waited till 9 months on my previous dog (if a month longer she probably would have gone into heat), and 6 months on my current one. Note smaller breeds are likely to be in their first heat at 7 months due to a faster maturity, thus an earlier Spaying date may be appropriate.

The male I had neutered at 6 months.

Over all it's a fallacy to think a spayed or neutered dog is going to get fat and lazy. For example a one time massive elevation of estrogen per the first heat isn't going to affect the metabolism 5 years down the road. But it just might affect the mammary tissue to the tune of 7% towards getting cancer. That's the choice for the female dog owner. How about the male dog? Again there is no evidence of decreased energy at least for my little guy. All I have to do is make a motion and my little male is ready to go- he's perpectual motion at times. He's also very trim and muscular for his size. What I did worry about was the question: Would the lack of testesterone somehow decrease his final height? Upon researching it, much to my surprise I found that neutering a male before 6 months may actually yield a larger dog at least in height. Exact opposite of what I believed going in.

In summary:

Males - there's no reason to wait to neuter past 6 months.

Females - before the first heat, else you have elevated the risk of mammary cancer. Large dogs 6-7 months. Smaller dogs 5 months.

Both - keep the diet sensible and you will have healthy trim active puppy dogs.