The Ugly Hitchhikers. We’re not talking about people on the side of the road looking for a free ride; that might make a little more sense, but what we’re talking about is foxtail grass. These seemingly innocent seeds will catch a ride on anything passing by – a mechanism that has helped them become a highly successful invasive species. You have probably felt one of these pesky weeds in your sock while hiking, and they sure are annoying. But for our dogs, they can be pretty bad news. “The potential to cause serious damage is low, but when it does, it can be catastrophic,” said Dr. Sonni Gilbert, DVM in Heron, Montana.