My three year old dog loves other dogs. He lives for going to the dog park and loves doggy daycare when I work a lot. He'd been to two different doggy daycares and neither have ever reported any problems with him being aggressive or not getting along with other dogs and both love him. I only switched because the second one was cheaper and wouldn't feed him and had longer more convenient hours for my schedule. They both only allow neutered and spayed dogs.
I got him at sixteen months and he apparently was never socialized so I did a lot of training and socializing. He used to be an adolescent hooligan and would just run and jump on other dogs but learned quickly that got him in trouble so he's much more polite now. He's very good and gentle with tiny puppies, small dogs, all females of any size, most neutered males and most unneutered males now. He'd never possessive over toys, balls or treats and will walk or run away and to me if another dog gets aggressive or possessive of a toy.
If an unneutered male starts a fight with him he'll defend himself but now it's all barking no actual fighting. If an adolsecent male tries to bully him he'll stand up for himself and bark or growl back and not back down then they'll get along fine.
My one issue is he really seems to hate large shaggy mountain dog types of dogs. There's a male Newfoundland who's a regular there who he used to go after occasionally but with me and the other owner holding them both on leashes and giving each dog treats and praise and me holding the other dog and me putting him on a leash every time that dog was there he's now fine with that dog and they coexist peacefully. He would only bother that dog if he thought he was defending one of his best buddies (like if the other two dogs were growling in play and he misunderstood).
Last summer I kept my horses at an awful place for a few months and there was a huge brown shaggy mountain dog, male, who was always loose, had no recall and apparently was never socialized. I always kept my dog on a leash, tied or in a horse stall while caring for my horses. As soon as I'd arrive every day this other huge dog would race over and leap on my dog and wouldn't get off no matter what I or my dog did. He wouldn't go back to the owner either and she'd refuse to restrain him just to let me bring my dog in to put him in a stall. If I left him in my car her dog would repeatedly jump on my car and my dog would go nuts lunging and barking. When my dog was in a horse stall the other dog would leap on the door. Because this dog was around two hundred pounds and would just tackle my dog and not get off or respond to social cues and my dog would be trapped under him and leashed he very quickly learned to hate this dog and would growl, snap, lunge, bark and bite but the other dog was so big and had such thick fur nothing would get rid of him. I'd even have to yell at him and wave my arms at him and couldn't get him to stay away. Anyway I quickly realized how awful the place was when the woman starved and almost killed my ancient horse and both of them lost weight and I moved as soon as I could find a place to move my horses.
Problem now is there's a young unneutered male leonberger who goes to the park. Until today my dog has been loose with him for the past six months no problem. Now the other dog is a year old and unneutered and keeps trying to play and also won't take no for an answer. Last week he was there with a dog walker and no issues both were loose and ignored each other. Last time he was there with his owner he kept trying to get my dog to play so my dog ran up to me and sat leaning on me on the agility thing (what he does when he wants a break, doesn't want to play or is stressed about too much barking or a fight among other dogs and goes to me for praise and treats) and was growling and warning off the other dog to stay away. Nothing else.
Today we get there before we even get in the gate, still leashed the leonberger was at the gate bouncing around. My dog immediately starts barking and lunging and snapping. Not at all normal for him but he is more nervous when on the leash. We walked in stayed leashed, the other dog is trying to play and jumping on him anyway ignoring all his warnings so he's not relaxing so I took him to the agility thing and got him to focus on sit, lie down and the other dogs owner put his dog on a long leash to keep him from jumping on my dog. I said they've usually been fine loose before and told a little of his history with the other mountain dog and that he's not usually aggressive.
This owners not someone I can work on training stuff with like the Newfoundland owner. When a bull mix puppy was growling and reacting similarly to his dog a couple of weeks ago he said the puppy had issues and should be euthanized. He didn't say that to me, but went on and on how his dog was a nice expensive purebreed that he's going to show and breed and how he's going to a show in a few weeks and can't have any marks or scars on him. He saw no holes in his dog's social skills of still jumping on my dog who was clearly telling him to leave him alone.
I'm not saying my dog's behavior was acceptable but if a dog growls or snaps at him he walks or runs away. Right after the leonberger left and I let him loose a tiny dachshund kept snapping and barking at him and literally chased him across the whole park once, just because he got too close. And he ran he didn't in any way bother the little dachshund. Lol.
And if he has such a nice expensive unneutered male show dog, I personally wouldn't be bringing it to dog parks and risking injuries beyond my control. When I was showing my horses I wouldn't let them be turned out with other horses during show season. Too much expense, training and work to be wasted for a stupid preventable injury.
So since the other owner is not exactly workable, should I chalk today up to bring on a leash or just never let him near a male large shaggy dog again? He might have been fine loose but I wasn't going to let him loose when he was acting threatening leashed. How do I fix this issue when there's no dogs like that around to get him comfortable with? He's friendly and respectful now with every other kind of dog, even other unneutered males.
I honestly like having a basically good non-aggressive dog for once and don't want to worry about an occasional large shaggy dog popping up out of nowhere. And this dog does go there a fair amount so he's got to deal with it, which he has until today. So how do I fix his issues with this dog and large shaggy dogs? I realize he's probably traumatized from that awful place and the bully dog jumping on him all the time. Working with humans, there'd be exposure therapy but there's no other dogs to expose him to except this one with the uninsightful owner who I don't want to have problems.
Interestingly enough, the Newfoundland got there a bit later and I wondered whether he'd be set off and go backwards. Nope he was fine, relaxed even chased after the same ball and the two of them were side by side at the gate greeting new dogs and getting along just fine. So either I really fixed his issues with that particular dog and he's still worried about large shaggy dogs in general, or this young hormonal pushy male is the exception.
Sorry this is so long!