Dog aggression and territorial

Help! My 18 month old staff has an attitude problem. He is completely evil when we come across other dogs while on our walks. I mean the complete works! Snarling, spitting, growling and lunging at any dog he see`s. It doesn`t matter what size of dog or what breed. He is a total nightmare. As soon as he gets a sense of another dog in the area he reacts and nothing I do can grab his attention while he is in that state. I just have to forcefully move him to a safe distance and ground myself to stop him pulling me over. I really can`t workout his problem. And I definitely can`t have him off lead as he bolts for the other dogs.
He has been desexed. He went to puppy glasses but was segregated due to how vocal he was a soon as he entered the room. We have tried 1 -2 -1 training but I found it very frustrating as every time the trainer was present he was as good as gold, butter wouldn`t melt. Which made it hard for me to present the problems I am having while on my own with him. Couple that with the fact that he is still pulling on the lead and I`m getting a complete strength and cardio workout each and every day lol.

All advice is appreciated

Have you tried teaching him the 'watch me' command so he will focus on you when he sees another dog or maybe make him sit when you see another dog, make a fuss of him so he associates another dog with a positive experience. With the pulling you could maybe try him with a halti it does help. I have my 2 on haltis if I take them out together as they both pull. Some dogs just aren't friendly with other dogs. He might also pick on your nervousness when you see another dog, you might tense up and he will sense that. Lola can be funny with other dogs and I know I get tense.

Have you had him since a pup? What age was he castrated & what was he like before it?

Can you tell me exactly what happens when you see another dog, and what you have done so far to counter his reaction to dogs, and what you've done so far to stop the pulling?

Sorry about the twenty questions!

Hi Caryll and Chiara

I have had him since he was a little bag of skin, brought him home at 9 weeks old ( much to the cats dismay lol ). He was castrated pretty much as soon as he was old enough on the vets recommendation.
He didn`t really take any notice of other dogs at first he was too busy exploring his surroundings and playing with toys. Then gradually he started to get more vocal, which started at the puppy classes with barking as he entered the room and taking a stance.
From the beginning I have always taken Monster to my parents when I`ve visited and they have an akita bitch - Kess. They seemed to get on for a while though they are always fed in different rooms as Kess doesn`t like him around her food. As Monster grew they would play in the garden together no problem. We would take both dogs out for a walk together and Monster seems to have a problem with Kess being in front of him. Then one day we walked into my parents home and he growled and lunged at Kess to which I took him straight back out the door. We were in and out a good 20 minutes or more before he walked in and showed some manners. He is not allowed through the front door any more. We enter through the gate into the garden.
Another dog when out walking doesn`t have to be any where near us, they just have to be in his line of sight and he will lunge then snarl and bark then the other dog(s) react to him its not pleasant. He is the same when in the car and we pass a dog.
There was a incident last summer where he was off lead in the park, he was there then he wasn`t. He bolted towards 2 dogs, both Staffies and would not come when called. The owner of the 2 staffs got hold of Monsters collar and he just stopped. He was like nothing had happened, so calm. No animals were hurt but the other owner was not a happy person, understandably. Since that day he is always on lead and he is muzzled. Then in September, October time of last year Monster and Kess had an all out brawl this time there was blood and both had various cuts and punctures but nothing too serious thankfully. I think it was a jealousy thing as Kess had come to me to say hello and Monster puffed his chest. Bang, they were literally at each others throats. Now he has a heavy chain lead attached to his harness at all times when we go round which seems to keep him from being naughty as it distracts him but Kess takes a long while to settle in his presence.
I`ve tried treats but is difficult while wearing a muzzle. Using a water spray worked for a few months until he got used to it and took no notice. Talking to him nice and calm has no affect. The trainer had me use the "BAHH" technique which I could not get used to at all and Monster looked at me like I was stupid but it always worked for the trainer.
And for his pulling we`ve had various non pull - harness` and the canny collar which was good for a short while until he started to resist it. He is improving though and not pulling as much. Its a slow progression.
I have tried contacting other trainers / specialists / behaviourist to which one person got back to me but I couldn`t do the date he wanted for a home visit as I had a job interview and he never replied to my emails or calls after that.
At home with me and the cats he has his moments but he listens to me. I just need that to translate to the outside environment

He may just be dog aggressive it happens sometimes and just can't be helped. Do you know someone with an older dog that is very well socialied that you could walk him with? You might want to walk him alone first so that his energy level isn't high and try the walk with the other dog away from your house or normal walking areas so that he won't be territorial