Dogs Toe Nails falling off?

For about the past few months i've been taking my dog to the vet for nail problems. I've attempted to search the internet with little success and while i trust my vets diagnosis as some form of fungal infection...his answers have been fairly vague so i was hoping to find something more specific to the problem if possible. So far my dog has lost 4 toenails, but only the outer shell of the toenail is falling off leaving a shriveled unhealthy looking nail. The most recent time when this happened the nail itself was partially hanging on and the vet was able to pull it off without the nail bed bleeding or causing any significant pain for my dog. From what my vet has said this could take several months of antibiotics to clear up which is not a problem, but i would greatly appreciate anyone's help who might have encountered a similar problem with their pet