Caused by the bacteria Corynebacterium pseudotuberculosis, Pigeon Fever (PF) is found in horses primarily in the western United States. However, in more recent years, cases of PF have been reported in the eastern and southern US. Pigeon Fever causes a very purulent (filled with pus) abscesses located most often at the level of the chest. Often, the owner notices a knot or a "boil" type lesion between the front legs. Ultrasound is used to diagnose the limits and depth of the abscess. Culture (and sensitivity) can confirm the diagnosis. Once these abscesses rupture, a copious amount of pus will leak from the site. Most PF cases will respond to antibiotics and anti-inflammatories. Recovery rates for the horse are varied and unique to each individual and is based on the patient's response to the prescribed medicines and the extent of the abscess. Currently, there is not a vaccine available in the horse.