Having been attacked by two dogs in a week in the Piddlehinton area of Dorset, I researched the legal position. Under the Dangerous Dogs Act a dog is not under control - no matter what breed - if it is not on a lead or does not have a muzzle. If a person has reason to believe they are going to be attacked they can take appropriate action including killing the dog(s). When reading how to defend against a dog attack the best advice seems to be to shoot it. However we are not allowed to carry offensive weapons in the UK, including pepper spray. Second to shooting a dangerous dog the advice is to use a stick and if possible ram it down the dog's throat as far as you can. I'm not sure how easy this would be in practise but we are allowed to carry walking sticks in the UK and I have one of those Nordic type stick that has a titanium tip. I've never used it until now and I have found that the iPod pouch on the rucksack, which is actually too small for an iPod, provides a useful strap to hang hold the walking stick.
Next time a dog attacks me I will retaliate.