It would be interesting to know the history of these missiles.  When I was on active duty firing TOW-II missiles ("Tube-launched, Optically tracked, Wire-guided" anti-tank missiles), the missiles used for practice had originally had live warheads which were removed before the missiles were re-issued for practice.  I can see how that practice could leave a 'trace' of residue that a dog could pick up.  FYI, they did this because firing the re-manufactured missile 'tested' the rocket motors used in a large lot number of missiles.  If  a practice missile's rocket motor failed to work, a huge bunch of missiles were immediately red-lined to see if the whole batch was bad.  Had one of those up at Yakima Firing Center once.  Paperwork and repetitive questions from O-5's and  O-6's lasted for months.