We got Ted 2 and a half years ago from the RSPCA, he is a springer spaniel cross border collie, now aged 6. He is a lovely dog, but not without his problems. He is really sweet with most dogs, he particularly likes Westies, JRTs and Golden Retreivers, but if he comes across Huskies, Rotties, Boxers or similar, he turns into a snarling monster
There is a disabled couple who live near us that travel about in mobility scooters and they have a cross breed dog that they walk with them, they used to have a JRT but i think he now lives with a relative. Ted goes out of control when he sees the scooter, with or without the dog, although worse with it, and once when off the lead ( with my husband) attacked the other dog!
This morning i was going to take him for a nice walk to the beach ( he gets a 2 hour walk every morning) but no sooner than we had got round the corner, he saw a different scooter across the road and started running and barking at it ( he was on a flexi lead, so under some control). I told him off for that, we rounded the corner and the relative with the JRT was across the road, Ted was pulling and barking and snarling at it I told him a firm NO a number of times, pulled him back, made him sit and look at me, not the other dog but he still wanted to go after it. I was so disgusted with his behaviour that i brought him straight home and sent him to his bed ! I know he is dominant and highly strung ( for want of a better description) but i want to put a stop to this before he does something dangerous.... any idea ?? Please help

You're going to have to desensitise him to mobility scooters. Do you know anyone with one that would help? If not you could hang out with him near a place that sells them, people will be test-driving them.
You start with him at a distance where he doesn't react, gradually moving closer (over days/weeks in necessary), keeping his attention on you by using treats or giving him a job to do (like sit, watch me). Over time he should come to associate them with treats=good things.
You'd do the same for his reaction to other dogs. If possible, have him walk with a calm friendly dog he knows.

First try and put yourself into his head, why do you think he goes off at mobility scooters? Yes, he is probably giving the impression that he wants to attack them, but why?

Difficult to say without seeing him doing it or knowing his history but if you were him do you think there is a possibility that you would be a little bit frightened of them?

Then, whenever you came across something that was a little bit frightening, imagine what you would think if you got told off or were punished? Confused? Well, Ted probably is too.

Dogs learn by association, when he says sit I put my bum on the floor, when I put my bum on the floor I get a reward etc, but they also do this all the time, even when you are not consciously aware of it. Lead goes on = time for walkies, bowl comes out = time for food and so on. Your dog is making associations all the time and you can either let this develop into a problem, or you can turn it to your advantage.

By punishing him for barking at the scooters you are associating that punishment with them, so instead you need to replace the punishment with something good until he associates the good thing with the scooters. That is not to say that you reward him for barking at them, you have to take teeny weeny baby steps and reward him for each one.

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Thanks for your replies, i think the desensitising idea is definitely one to try, as a first step, i'm not sure if it's the scooters that started the problem or he didn't like the dog and now associates the scooters with the dog, he doesn't kick off at all of them, just some When we go out, i can tell if Lizzie ( the scooter dog) or Bear ( the big male Husky) have been about because Ted can obviously smell them ( or their wee lol) and he pulls ahead in an effort to find them! I think possibly there is a little bit of chase instinct involved too, he used to lunge at bicycles and he will bark and run at a vehicle if it revs hard. I do think that it could be about fear as well, so will try harder at rewarding the good behaviour I am firm with him but not harsh, i just try to get him to focus on me rather than him trying to get over to have a fight. He has obviously been mistreated/ hit in the past He is a bright boy and has a larger than life character, i want people to see the loving, intelligent, funny boy that we do