What I find confusing in the article is the cutting off of the phrase “increased rate of cystitis and decreasing age at gonadectomy was associated with increased rate of urinary incontinence. Among male and female dogs with early-age gonadectomy, hip dysplasia, noise phobias, and sexual behaviors were increased, whereas obesity, separation anxiety, escaping behaviors, inappropriate elimination when frightened…”
The article goes on to imply that all these problems/behaviours are increased, but the "whereas" could just as well have been part of a sentence saying the obesity, SA, escaping, inappropriate elimination were decreased. We don't know, as the full phrase is not quoted.
I don't trust articles that do selective quotes like this.
Furthermore, there is no proof that the early neutering caused the problems. It could have been that some owners saw problems developing and decided to neuter because of them. However I don't agree with neutering at the early ages that seems to be increasingly common. The dogs should be mature and fully grown. I would apply the same to cats.