Spaying and Neutering
My recommendation for spaying and neutering puppies is for the procedure to be done at approximately 24 months.
Sex hormones play a role in helping the growth plates close. By spaying/neutering early, the growth of the leg bones is shifted just a little bit, which can cause slightly leggier development, subsequently affecting the way the bone sits in the joint. As a result, dogs that are spayed/neutered earlier may have a higher risk of elbow dysplasia, hip dysplasia, or cranial cruciate tear (source).

Puppy x-rays showing bones have not grown together yet.
Example: These are littermates - one was neutered pediatrically, the other left intact. Notice the permanent puppy-like body of the dog on the left. His head is narrow, his chest is narrow, his angulation is bad, he's taller than he is long because growth plates don't get the proper signals from testosterone or estrogen on when to close.

Example: These are littermates (Source)
An additional area of caution I will provide about spaying and neutering is that it may affect the texture and density of your dog's coat. Instead of blowing their undercoats twice a year, they may start shedding their undercoats year-round, which makes maintenance a bit more challenging. Here are some quotes from other owners about spay coat:
"One of my Eurasiers had to be spayed due to pyometra. While her coat did not get tremendously thicker as she was never very fluffy, the coat got much tougher to brush out and line comb and she was no longer shedding only twice a year based on her hormonal schedule but more or less year round." - UM
"I don't have a Euraiser (yet) but had a Keeshond who was neutered and Samoyed who is still intact. different breeds but the Euraiser has them. In my opinion the neuter coat is real. Longer and harder to keep from having the undercoat matt, especially on the belly and rear legs. My Samoyed's coat is crazy easy to maintain currently. I don't plan to neuter him unless medically necessary now that I understand more (My Kees I got in my early twenties and neutered b/c I didn't know any different)" -LK
"We spayed Harley when she was seven years old (September of last year) and this year we've noticed her undercoat doesn't come out as easily, that her mane fur and feathers are a lot longer than before, and that she sheds a little all the time instead of a big shed a few times a year. Still manageable though! We have decided to get her groomed more often though, every three months instead of once or twice a year." - JN
@harley.the.eurasier - posted with the permission of the owner
"After spaying our first Eurasier (and she’s age 7), her coat became coarser, longer and thicker. It had been silky prior but definitely had a coat change after spaying. She does not drop the undercoat at all~ needs to be brushed/combed out and even then it’s difficult. I will not alter any further double coated dogs I have in the future with this being one of the reasons. The coat can (not always) get difficult to manage after altering." -TL
"S got a Humongous coat after being neutered - he looked like a haystack when he sat down. It took about 4 years for it to normalize a bit - still on the long side, but less thick and more easily managed. That said, not all respond to neutering the same way; my other boy, I, got a marginally thicker pelt but really quite manageable." -DW
"I neutered G close to two. His coat definitely changed. Hes still a gorgeous dog, but his coat is a challenge to keep up with. Much coarser and super thick around his neck and rear end." - MC
To be clear, I am not against spaying and neutering - only against pediatric spay and neuter!
With spaying and neutering in general, there are advantages and disadvantages to both, and it takes a very responsible home to ensure that their intact pets cannot procreate. Dogs can chew through walls, break out of their crates, and even mate through chain-link fences, so it is up to you to determine if you are dedicated enough to keep your dogs from breeding. Altering your pets also gives you a lot more flexibility on where you can go (eg. some doggy daycares or boarding facilities will not accept intact pets) and potentially reduce the risk of prostate or ovarian cancers as they age. Please educate yourself about all the potential outcomes and decide accordingly based on your lifestyle and risk tolerance.
Additional sources:
- Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence
- Assisting Decision-Making on Age of Neutering for Mixed Breed Dogs of Five Weight Categories: Associated Joint Disorders and Cancers
- Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers
- Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers
- Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence