[Dechi]

Your dog won’t have time to develop like a male would (more muscle, broader head and shoulders) if you do it at that age. It’s not as noticeable on a toy, but still. I’d wait until 18 months, or at least 15.

 

[Dechi]

This is what you do to your dog if you neuter before he is done maturing. It looks so unnatural and bizarre.

Full article, since you can’t click on the picture :

 

[Dechi]

But Dechi, those are all large breeds. Also, we don't know if quality of breeding factored into those differences, nor do we know how old the dogs were at spay/neuter (could have been 8 weeks for all we know, right?). Toys reach maturity a lot faster than large breeds. If I ever get a toy breed again, I would be okay with early spay/neuter (meaning around 6 mos.) and I would have to be--it is actually required by most top Maltese breeders.

She also talks about small breeds in the other link.

As I mentioned (I think), it doesn’t show as much in small breeds, but even if it doesn’t show, hormones still have a role to play.

The first dog I bought myself was a boston terrier. His dad was such a nice fellow, very muscular, with a broad head and shoulders. I had his son neutered when he was 6 months old. He was the best dog I ever had, but he turned out to be very lanky, not muscular at all and he looked kind of odd. Not like a male, not like a female. For lack of knowledge, I turned a beautiful being into something bizarre. Never again !