This is just one example of why I don't neuter (or spay) my dogs before maturity. The first picture is Marvel at 6 or 7 months, a common age to neuter . As you can see he has a very narrow front and lacks chest. The second picture is Marvel just after his first birthday, another common age to neuter . He has slightly more chest / breastbone but is still very narrow in front. The third is Marvel last week at 16 months. The difference here is pretty obvious and dramatic , his entire front has changed and filled out a lot. And he still isn't a mature dog , I expect to see even more changes in the next year, he's still narrow. Giving your puppies a chance to mature and have the hormones needed for growth is so important in keeping them structurally sound for life. Good structure isn't just important for sport or breeding dogs , it also helps to prevent common injuries in pet dogs like torn ligaments and shoulders. Just something to consider when owning a dog . Marvels change is a great visual because the changes are so obvious .