Due to the drought here in texas last year there were alot of horses getting pigeon fever, one being my mare. She started with a lump in her chest area that in time came to a head (had called my vet and he told me what to watch for so he knew when it was time to come out) at which point vet came out lanced/drained it (make sure you have thick plastic bag gloves etc so hopefully your can concentrate most of the draining into a bag for disposal, I placed the bag in a 5 gallon bucket) . She was stall bound for about a week, vet didnt have me applying anything but scarlet oil and some swat to go around the wound, also get rid of any flooring or bedding that may become contaminated with the drainage. After all the drama, it healed up great and you cant even tell she had a hole the size of a baseball. I do know that I was lucky and she only had one abcess, some I understand may develop more. It really just looked like in the beginning she got kicked in the chest (had that problem about 2 months prior to that) but when the swelling didnt go down after a day knew something was going on. My other 3 horses didnt get it, honestly the vet said he thinks natural immunity may have something to do with it, because a barn of 100 horses and only 2 get it suggest that. But they really arent positive. There are also the cases of internal pigeon fever and those are alot harder to diagnose and treat, in my case anibiotics were not given, but with the internal cases I know long term antibiotics are the prescription. First thing my vet said there was not to panic, because I didnt have a clue what pigeon fever was. Fly control is key though too.