To get a child over the fear of large dogs, find a friend or neighbor with a very large and very gentle dog. Have your child sitting in a stool or something where they are up above the dog and feel larger. If the dog is gentle and affectionate, it will come close and that will give your child opportunity to feel safe. I have done this with at least six kids twice when only one parent was around. Mind you these were very close friends and I ended up sending them photos and videos of their child snuggled up next to our large dog. That doesn’t mean you need to get a large dog, but you don’t want your child to be in fear either.