How can I stop my 5yr old being terrified of dogs?!

[tigwig]

Hi everyone, my daughter is absolutely terrified of dogs and today the afternoon was just ruined by her running and screaming and crying because we were having a picnic in a local beauty spot which of course is full of dogs too. She has always been scared of them, never attacked or anything like that but my SIL has one and because it is kept mostly in the garden and has no attention, the second it sees someone it gets giddy runs and jumps up. This is the only thing I can think of why her fear started. Today, she was terrible. Because we were near a lake, she was paddling but so were the dogs! They did run about near her but not at her. As soon as she sees them running she cries and runs away which of course can make some dogs chase her. I have tried telling her they won't hurt her etc etc and even some owners have let her stroke them which she will do if they are calm. Its just when they run about she hates it. We had to pack up and go early cos she was just crying and begging to go home! Do any of you have any idea how I could get her out of this? Unfortunately I do not know anyone with a dog apart from SIL with the untrained giddy little thing which daughter already hates!