Greetings, and thanks for the question.

Sorry to hear about your filly, but a pharyngitis is much better than having a case of strangles.....!
Some horses can be carriers of the strangles bacteria without showing any of the clinical signs. And yes, there is the possibility that it could be spread to other horses, although at this point it seems as if it may be minimal (depending on how long the filly has been in the environment of the others...if it's been a month or more, chances are minimal). You might consider, however, suggesting that the other horses in the barn be vaccinated against strangles, just to be on the safe side. Strangles is normally seen in it's worst stages in younger and older horses, especially non-vaccinated.

Hopefully your filly's pharyngitis is resolving, and there won't be any further consequences. Consider yourself lucky!

Thanks, XXXXX XXXXX let me know if you have any further questions.

-Dan