Stages of Wound Healing in Horses

There are three basic “stages” of wound healing starting from the moment that the wound is created until all healing and scarring has taken place.  These stages overlap but their division into stages simplifies understanding.  Depending on the wound in question, the healing process can take months or longer.

Stage 1 :
The initial stage, lasting from the moment of wounding to a few days following, involves the formation of a clot and the recruitment of infection fighting cells and more blood flow to the area.  This process allows the breakdown of irreversibly damaged tissue and foreign material, and controls wound infection.

Stage 2 :
The next stage involves the creation of a scaffold in the wound defect (granulation tissue) that serves as a basis for more mature tissue to be laid down and for skin to migrate over. This stage lasts from about five days to several weeks after wounding.  The granulation tissue produced is the red colored filling tissue so familiar to horse owners which, when it grows above the wound bed, is known as proud flesh.

Stage 3 :
This stage involves wound contraction as the skin is actually pulled together by cells in and around the wound, and skin migration, as skin cells multiply along a front and migrate over the wound. The healing wound then gains strength over weeks to months as more organized, tough tissue replaces the early scar.  This stage actually starts as early as 2 days after wounding and so overlaps the other stages.

How well wounds heal depends on many interrelating factors affecting each of these stages.  Wounds penetrating internal body spaces like joints, sinuses, and the abdomen often result in infection of these structures, which can be life threatening.  Wounds that contain foreign bodies like wood or other material will not heal until that material is removed.