Strangles is a highly contagious respiratory infection in horses, donkeys and ponies caused by a bacterium called Streptococcus equi subspecies equi. It can affect any age or breed although younger horses tend to get more severe clinical signs. The incubation period can be anything from 3 days to 2 weeks!
IF STRANGLES IS SUSPECTED IN YOUR ANIMAL YOUR VET MUST BE CONTACTED IMMEDIATELY.
Horse with a purulent nasal discharge and a burst abscess under its ear
(Photo courtesy of MSD Animal Health)