--she and her compatriots are constantly losing toenails to the trauma of running.

It's actually not that hard to lose a toenail, or a fingernail, to trauma--sudden or low level constant trauma--especially as we get older.

It looks frightening, but most of the time these will grow back. And they will look very ugly as they grow back. In fact, the new toenail will often look distinctly different from the old one, especially if there was trauma down to the nail bed. And, having this happen to a toe makes it more likely that it will happen again.

But, you're doing the right thing with Alan; getting him to the podiatrist will ensure that the area is cleaned, doesn't become infected, etc. And then you can watch the toenail grow in again over months, as long as he doesn't smack that foot into anything else.