Open wounds in horses heal through overlapping phases, beginning at wounding. it is important that each of these phases functions properly, in order for a wound to heal cosmetically and functionally in a reasonable period of time.

The second phase of wound healing is called granulation, in which a scaffolding of budding vessels and connective tissue (granulation tissue) begins to fill the wound bed. Granulation tissue formation is critical to wound healing but can become excessive under certain conditions.

Proud flesh (excessive granulation tissue) is commonly seen in slow healing wounds, especially in the lower limbs. It appears as red or pink tissue within the wound bed that becomes known as "proud" when it grows above the level of the surrounding skin. Proud flesh can stop the healing process, as it physically prevents the wound from closing in from all sides - the processes of wound contraction and epithelialization.

Importantly, proud flesh is also a sign of an improperly healing wound due to an underlying problem. This might include infection, the presence of foreign material in the wound, excessive movement of the healing tissues, lack of adequate blood supply, or the involvement of anatomic structures that inhibit the natural healing process.