'Fox tails' are called other things in other places too- can't remember all the names at the moment, but it can be just about any type of plant or grass awn that pokes and works its way into ears, noses, shoes, etc. Around here, the biggest 'fox tail' is actually cheat grass. People talk about pulling cheat grass (awns) out of dogs all the time. I've had to pull gobs of it out of ears... ouch! Definitely done under sedation. Even my own dogs have had to have some pulled.