I would suspect that it would depend on the age it was done (before some ingrained behaviors formed) but in many cases it is more about the individual dog.

Usually intact dogs (male or female) will display more serious behavior traits...ergo one of the many reasons for neutering/spaying. Your average owner is not equipped to handle whole/intact dogs. They require far more solid training & management.

Also late neuter/spay may only modify not remove some of unwanted behaviors. Once they are well ingrained...they may not be changed. Other then the obvious loss of ability to breed.

All of which I am sure most people know.

 Quote: Betty Landercasp

What role if any do folks think castration has in this?

From what I've seen, it depends on the dog. I've seen no difference at all, and I've seen aggression taper off with the loss of testosterone.

I think brain power has something to do with fighting. A really smart dog can manipulate situations without fighting.

The dog I had who fought the most was a bull terrier (spayed) who was also the stupidest dog I have ever owned.

I also fall under the "it depends on the dog" thing with castration. Gam loves all dogs and is intact, but is also the one that gets targeted by aggressive offleash intact male dogs even when his body language is 100% friendly and non-confrontational. The type of dog that would come up and attempt to attack a completely friendly intact male who's exhibiting no inappropriate behaviors is the same kind I'd imagine would have issues living with an other intact male. These are also dogs who I think would have an issue with intact males even if they were neutered.

Ryuk treats intact males no different than neutered ones, the only dogs he treats differently are young little puppies (which he will let get away with murder), females in season (...he flirts...a lot), and with very rude or "dominant" dogs he will refuse to acknowledge posturing or pushyness and will turn his back and go out of his way not to reward inappropriate behavior.

Gam is similar, he doesn't get to be around females in season for obvious reasons (but if they're close is OB will get flashy then he'll melt into the floor and get all shy the closer they get) but he's a complete pushover for little puppies, and tries very hard to avoid interacting with rude behavior. It doesn't matter if the other dog is intact or not he's pretty neutral. He can be a little more posture-prone around rude intact males but that is directly the result of two problems at a dog event where two dogs who targeted him for being intact got off their leads and came at him, they didn't get do any damage but it was so unprovoked that I think it confused him a bit. We've worked through it and really don't have the problem any more and his default is still a polite happy greeting and offer to play.

 Quote: Betty Landercasp

I think brain power has something to do with fighting. A really smart dog can manipulate situations without fighting.

The dog I had who fought the most was a bull terrier (spayed) who was also the stupidest dog I have ever owned.

I used to keep my brother's WBT while I was showing him. That's the ONLY dog that my wife ever made the comment "If you ever bring one of those home there will be some serious decisions to make". Sure glad she was laughing at the time.