I found this in my drafts from March 29, 2010!!! Time to get it out of there.
Every once in awhile our sheep will develop an abscess. We’ve actually had two ewes develop them on the side of their neck recently. I’m still looking in to that a little more to see if there is a certain condition that causes abscesses in that area. In any case, treatment for an abscess is basically the same. An abscess is a boil or a pocket, usually containing purulent (pus like) material. They usually form when their has been a puncture that scabs over and cannot drain.
It helps if someone else can restrain the animal, giving you access to the wound. Wipe or gently soak the area with an antiseptic. I use a Chlorhexadine solution. If there is an obvious scab you can try to loosen it by applying a warm compress of the antiseptic solution. If I can get the scab off most of the time the pus will drain out from underneath. If there is no obvious scab or wound I pierce the area with a 20 gauge needle to let the pus out. Then I usually flush the area with a lot more antiseptic solution. You can use a large syringe without the needle to draw up some antiseptic and flush right in to the hole you made. Depending on the severity of the wound an antibiotic injection may be warranted. If the sheep doesn’t have a fever I usually wait a day and if things are healing nicely then I skip the antibiotic. During warm weather you may need to apply a protective ointment such as Swat clear.
These posts are in no way meant to substitute the care of a professional veterinarian. I only share my experiences with the hope of helping you become a better shepherd. If at any time you think you might be doing more harm than good STOP and call your vet instead.