Hi Paul I can't say which is the right way, I can only tell you what I would do given the set of circumstance you describe, I would take a different course of action..and have done so with some success...

Firstly I don't like long training leads unless I am teaching recall, they offer very little control and I see little point in them, if a dog is attached to you by a lead be it two feet or ten feet away it can't go at a faster pace. To me either a dog is on the lead under control or it is having a run somewhere suitable.

Regarding the off lead dogs, I would try to avoid confrontation whenever possible if I saw one approaching. I would shorten the lead and turn in the opposite direction so the dogs were not eye to eye, if the loose dog is going to attack it may well do so but there is less chance if you remove eye to eye contact .

If the loose dog then attacked my dog from behind , assuming I had a jumper of some kind I would throw it over the dogs eyes and ask the owner to grab his dogs back legs and pull it off mine in a wheelbarrow fashion, the shock of this should cause the agressive dog to let go while the owner puts it on the lead.

Our pup is not allowed off lead because her recall is very selective, however I know that if she's restricted when another dog approaches (aggressive or not) she tends to get a bit stressed. She's normally on a 30 foot training lead so i just wind it up a bit to ensure that if I have to remove her from a situation I can - normally though she's fine and now that she's getting a bit bigger than the majority of adult dogs she meets we've been pretty lucky that the majority of confrontations have passed without harm.

There was one horrible little JRT though that kept winding her up but now she's home in Scotland all's well so far.

Carrying a knife, baseball bat, pepper spray . . OMG!!
That's AWFUL! Not to mention illegal . .

There is a spray-cannister that you can take with you that emits a loud hissing sound (nothing else) - which dogs dislike. I think it's called Pet Corrector or something . .

I've heard the 'wheelbarrow' trick before to pull off an aggressive dog . . personally, I'd keep the lead ON my dog, because if you unleash/let go you loose what control you had over the situation. If you did use the Pet Corrector spray and you'd let your dog off the lead, YOUR dog might take flight, too!!

My dogs are nearly always off lead in the park/woods but they are too well mannered to cause the situation your describing. However, Syd was attacked by a Weimy one day who simply wanted to have a go. The other owner was damn useless frankly, all we got was he's not usually like this. Have to say we didn't believe her, because Syd does not react to aggression not even under provocation he simply walks away, but this dog was having none of it. As he was off lead he dealt with it himself, gave himself space by running in huge circles but still would not react. The weimy eventually gave up and the woman walked off without so much as a sorry.

Tara isn't aggressive, but I do tend to keep her on the lead. There was one incident when I was down the beach and tara was off the lead (she doesn't ever run far from my side) we were sitting down when suddenly this massive dog appeared and started bouncing all over us, it really scared Tara and Tara just kept trying to run away, but when the dog knocked Finn (my step-son) over Tara started to get really cross, she didn't go for the dog but tried to chase it away. The owner (finally) appeared, but instead of trying to control her dog, she laughed and said that he was only being friendly and that he wanted to play! Eventually she got the hint and then had the cheek to say to her dog "come on, that dog obviously isn't as friendly and doesn't want to play". I was so annoyed! Another reason why I tend to keep Tara on her lead around other dogs, not because Tara would ever go towards another dog, she wouldn't, but because I never know what the other dog will do.

Depends what country your in. I think even penknives are still legal in UK no???? Pepper spray I dont know if its legal in UK or not, bag of pepper isnt though and as for the baseball bat....any solid wood stick or break stick....have you ever had a dog die after being on a leash and being attacked by about 5 loose dogs? I have, I was 13 or 14 at the time the dog was a well trained guard dog, on the leash and about 5 loose dogs came after him, I panicked, didnt know what to do...a guy across the street yelled at me to let go of the leash which I did, the leash had already got wrapped around my legs so my (grandads) dog couldnt get loose, he died about a week later from the wounds despite having surgery....it wont happen again.

Have you ever seen a child getting dragged around the ground by a couple of dogs that had attacked his little poodle....the dogs turned on the kid, an old lady with a pomeranian on a leash that was attacked by a large dog, she picked up her dog and the large dog put the lady in the hospital for about 2 weeks, multiple bite wounds and shock....and her dog was killed, a woman that rushed her badly mauled dog into an emergency clinic and then she passed out from the severe bite wounds on her arms, she lost all use of one arm...permanently disabled because some idiot refused to keep his aggressive dog under control.

I will always try and avoid any injury to any dog and myself if a dog I have is attacked or threatened by another dog but sometimes there are extreme situations and you need extreme measures to stop it, the device you mention....Ive never heard of it until recently, I havent been able to find it where Im living right now but of course Ill look into it when I move but Ill be totally honest, if my own dog, a dog that is in my care or myself are attacked by any animal (or human) then my instinct is to protect 'my dogs' and myself....whatever it takes.