AStrangles is caused by a tough, gram-positive bacteria called Streptococcus equi. I hope the owner of this farm is working with a veterinarian, as indiscriminate use of antibiotics can cause the disease to linger in horses for extended periods of time.

The single best thing to do is not move any healthy-appearing horses around, since you don’t know which horses are incubating the disease. If possible, the sick horses should be strictly isolated because they need more intensive care, and any nasal discharge or abscess material is highly contagious to other horses. Other factors that spread it are human hands, towels, grooming equipment, flies, and anything else that touches the discharges from a sick horse, then lands on a healthy horse’s nose.

Horses which have been in contact with sick horses (from the same pasture or barn) should have their temperatures taken twice a day, since a rise in body temperature of 1.5$deg;F over normal is an indicator that the horse might develop the disease. Horses with fever should be immediately isolated