In the case of a group I abscess, the pus is usually colored gray, black or brown, the color being due to bacterial breakdown of horn. The pus from a group 2 abscess is usually much paler - the usual pus color, yellow or creamy. It is important to note the color, as the paler pus may be the first indication that the deeper structures of the foot are involved. Having established drainage, the pressure is reduced on the sensitive structures and the horse may quickly show a marked improvement in lameness. The treatment, however, is far from complete.
Bacteria remain inside the foot.
All the infected material needs to be removed from under the sole to prevent spread of infection, or reinfection. This is where the decision must be made, to make a big hole or a little hole. Or, in other words, remove all underrun horn or make an access hole for drainage without removal of underrun horn. There are two schools of thought on this question. Then the abscess pocket, the area under the horn, is flushed out through the hole with water, saline or antiseptic solution, depending on individual preference.