it sound like streticoccis zooepedemiccus its very common in young horses, can cause abcesses, it is contagious but not as bad as strangles, tell the lady to ask for a swab as it can be treated with antibiotics unlike strangles, hope this helps.
he has moved on to another yard, and then from what i hear made another move, to a field with a gelding and reports are he is happy and due to be gelded soon.
It's a happy ending really to something that could of gone the other way.
"Until one has loved an animal, part of their soul remains unawakened." www.northwalesarab.co.uk