I brought in a horse 2 weeks ago and missed the early signs. He had a lot of mucus and on the second day sneezed a "gallon" of snot on my jeans - LOL! I thought it was just a cold. On Tuesday I noticed a large knot under his jaw - still didn't think of Strangles until yesterday when the abscess broke open and the poor guy now has a bloody, pus draining mess under his jaw.
Fortunately Hollywood has had his vaccination against Strangles and the older pony is just that - older. The one at risk is the 3 year old pony gelding. There's no point in separating them at this point.
Just a warning to those bringing in new horses - watch them carefully and segregate them if possible for 2 weeks.