Dealing with loose aggressive dogs on walks

This can be quite a problem for some dog owners, what do you do if a loose dog comes over to you and your dog, the situation can be quite intimidating especially if you have a small dog and the one coming toward you is much larger or aggressive.
The reason I have written this article is because I was on a dog forum recently and read a hart wrenching post from a lady who held her dying dog in her arms after it was attacked in front of her by a loose dog that snapped it’s neck.
I do not always keep my dog on a lead but I have a rule I always use when I am out with her, if she is off the lead and I see another dog with it’s owner if that dog is off the lead I keep Brandy off hers, I make the assumption that the other dogs owner knows their dog is all right interacting with other dogs, however if the owner has their dog on a lead I then put Brandy on hers. This is because I feel if the owner of the other dog is unsure how their dog will react to mine I should do everything I can to help their dog be combatable, this is just a rule I use when out with Brandy.
There are times when you need to deal with dogs who’s owner is either not responsible or is not around in there situations I believe there are a number of options you might consider taking.
Dog with owner
If you come across an aggressive dog off its lead but with the owner then it might be worth having a quick word with the owner and suggesting he keep his dog on a lead when other dogs are around.
Aggressive dogs
If you are lightly to come across aggressive dogs on your walk then there are three things I would recommend you could carry with you to deter an attack.
Pepper spray
You can get dog safe pepper spray, this will cause the dog discomfort and stop the initial attack, it also acts as a deterrent from future attacks, if a dog recognises you as someone who has caused him pain he should avoid you in the future. I think this is an extreme measure and I would only use it if there were lightly to be in danger of harm to Brandy or myself.
Ultra sonic alarm
You can buy ultra sonic alarms that can be heard by dogs but not people, this will cause the dog to get distracted and the sound will not be pleasant to him but should cause no permanent harm.
Carry a stick
This is an option you could consider a walking stick waved at a dog as it starts to become aggressive can often deter an attack, and might stop the situation developing further.
Call the dog warden
Whatever tactic you decide to take you should call the dog warden or animal welfare as soon as you are able to, the dog might be lost and hungry or it might attack someone who is not as prepared so reporting it might help it and save someone the hart ache of loosing a loved pet.