• Dog Dazers can be ordered from: Dazer UK, 204 Broadway, Peterborough, Cambs PE1 4DT, (tel 01733 315888) price £37.95 incl battery.

A few years ago when I was information officer for the Ramblers' Association, I tested one on a series of walks with a success rate of around 60%. On some dogs, it had no effect whatsoever, and, rather alarmingly, it seemed to make a few even more agitated. One problem is that the high-frequency sound wave is ineffective beyond 5-10ft, so you have to be quite close.

My conclusion? A useful last line of defence - but so is a large stick, and it doesn't cost £38. The best way to deal with a dangerous dog is to back away slowly and quietly, and then look for an alternative route if possible.
Andrew McCloy

• I used an ordinary rape alarm (much cheaper - about £5) against a pack of sheepdogs in the Pindos Mountains. Greek sheepdogs are notoriously ferocious, and these were racing towards us. The rape alarm stopped them dead in their tracks. They then dithered long enough for us to back away.
Liz Allen

• The Dog Dazer is available from Cyclists Touring Club, 69 Meadrow, Godalming, Surrey GU7 3HS (tel 01483 417217) price £34.95. You can read about the Dog Dazer in action in The Wind in My Wheels by Josie Dew (Warner, £6.99).
Cherrie Stevens

• I recently bought a Dog Dazer and regret to tell you that while it had a pronounced effect on cats, it has had absolutely no effect on any dog I have tried it on. I wrote to Dazer UK to complain. A sweet-talking rep phoned back and told me that dogs only hear the high-frequency signal when they are "sufficiently aroused", which sounds like a cop out to me.
Charles Arthurs