Spaying/Neutering your puppy too early DOES indeed negatively affect the dog physically & mentally... (you're literally stopping hormone production that is responsible for brain development, bone/ligament/muscle development, etc.) 

I don't care what your local shelter/ rescue or even your veterinarian has told you... 
((this has been scientifically proven--- do your own research! -- especially before you bring home that 8-12 week old puppy from the shelter/rescue//etc))
✨️✨️it is 🚫NOT safe🚫( or smart) to pediatric spay/neuter and absolutely alters your dogs growth BOTH physically & mentally .... ✨️✨️
Remember this before you want to remove crucial hormones that the animals require to grow properly...

It is highly recommended to wait until TWO years of age to spay/neuter (unless it's considered medically necessary -to be  life saving only- ie: pyometria, prolapse, etc. ))

More info here and here