Wow, there is alot of old mis-information flowing.
Minimimun quarantine for new horses is recommended to be 3 weeks.
Recovered horses can shed the bacteria for 3-6 weeks or more after they show no symptoms of strangles.
Symptoms of strangles can appear 3-14 days after exposure however horses may also carry the bacteria and be subclinical (sick but not seriously so that it's not diagnosed) or asymptomatic but shedding the bacteria. Thus any incoming horse no matter where from should be quarantined whether they look sick or not.
The bacteria does NOT survive that long in the environment.It most definitely is not the cause of infections that occur from year to year in a given facility. The bacteria that causes strangles is very susceptible to the bacteriocins found in the environment and even in the best of laboratory circumstances (perfect temp., no bacteriocins to damage/kill it) it only survives outside the body for 63 days.
The reason for recurring infections from year to year in a facility is from carriers-horses who harbor the bacteria for months or years often without showing symptoms of disease after their initial infection. These horses shed the bacteria at random intervals and serve as a chronic source of environmental contamination and infection of other horses.
Antibiotics are now used more often with Strangles because there hasn't been evidence to link antibiotic use to the development of ******* strangles. If it is going to be done is should be started prior to the beginning of abcessation otherwise it will only slow the course of disease. Or in the case of serious symptoms which lead to high fevers or restricted breathing.
All of this information was published by the Academy of Veterinary Internal Medicine in 2005.
Licensed Veterinary Technician