Nature wants wounds to heal and exuberant granulation tissue or “proud flesh” as it is
commonly known, is part of the normal wound healing response. Granular appearing tissue
develops into large fleshy outgrowths anywhere on the horse’s body, however it is more
commonly found on the horse’s distal limb. Normal granulation tissue looks red-pink in colour
and has a flat surface with no obvious clefts or changes in colour. It is composed of small blood
vessels and fibroblasts, but has no nerve supply. The body forms granulation tissue naturally, in
wounds that are left open to heal for several reasons. These reasons include helping the open
wound resist infection, it is the base upon which the new skin cells are supported while they
migrate across the wound to provide a healed surface (surface epidermal migration). While the
epithelial cells are moving across the wound they produce a chemical signal that encourages the
cells in the granulation tissue to contract. This pulls the edges of the wound towards each other.
Wound contraction is particularly important in wound healing because it not only reduces the
distance the cells have to move, but increase the rate of wound closure, pushing out any debris.
There are several reasons why a wound fails to heal, it could be due to infection, foreign bodies,
dead tissue, movement of the wound site, poor circulation, or an excess of granulation tissue.
Although granulation tissue is a natural positive part of the healing process, it can in some cases
cause further problems to the animal. The horse’s ability to produce granulation tissue
compared to other animal is rapid and therefore the tissue production, if not managed can be
too great and protrude out of the wound. This is known as proud flesh. When proud flesh is
produced the wound healing process is impinged because it prevents the skin cells covering the
wound. Proud flesh can appear for a number of reasons including wound management,
excessive movement, and minimal soft tissue coverage around the wound, infection or lack of
blood supply. These issues are particularly important if the horse’s wound is on the lower limb
because these areas do not have the soft tissue (such as muscle) to provide a good blood supply
or extra skin to the wound. They are also more susceptible to infection because they are closer
to bedding or dirty surfaces. This area is also continuously moving and therefore it is difficult to
limit the movement and stretch to the wound and with wounds in the limb having a heal rate of
0.09mm per day on average compared to the heal rate of wounds in the body as 0.2mm per day
on average it is extremely important to manage this area.
If open wounds occur, particularly in areas that are prone to proud flesh then it is paramount
that steps are taken immediately to prevent the production of proud flesh. Any significant
wound should obviously be treated by the vet as soon as possible, keeping in mind that correct
and timely management is crucial to a good outcome in the healing process. The wound can be
covered or in the case of a limb wound be bandaged until veterinary care can take place. This
will not only prevent any dirt or debris contaminating the wound but will also prevent the
production of proud flesh as the pressure from the bandage or gauze prevents the granulation
tissue protruding out from the wound. Coverings are not advised for long term treatment of
proud flesh as they can create a warm or moist environment, perfect for bacteria to live in.
When proud flesh is present in a wound surgical treatment will usually be needed. The excessive
tissue is cut back using a scalpel blade which is a painless process because the tissue does not
have any nerve endings. Blood lose can be quite significant but the process reduced the bulk of
the wound and at the same time limits the healing steps of the granulation tissue to a minimum.
This then allows the edges of the wound to contract and cell migration to begin again across a
smaller margin of the wound. In server cases the wound will have to be cut back at its edges and
therefore a skin graphed may be needed, the use of phototherapy is also recommended.
Using red light phototherapy on the edges of an open wound will optimise the rate in which the
edges of the wound come together. This works by removing abnormal cells from the wound,
promotes superficial vaso-dilation, which in turn enhances epithelial growth, collagen synthesis
and capillary growth. Phototherapy is a straight forward procedure and therefore is no reason
for it not to be tolerated by all horses. It will assist with the organisation of the collagen fibres
therefore forming new tissue.
Prior to today’s research it was thought that using caustic agents such as copper sulphate would
kill the proud flesh although this is not used today because it severely inhibits healthy tissue
around the wound prolonging the healing process.
If proud flesh is apparent and the wound is not treated correctly, there can be major
implications to the surrounding tissues. The proud flesh will continue to grow to the point when
the original wound is not identifiable. Debris in the wound cannot escape and therefore migrates
further into the wound infecting it and causing a larger scale of soft tissue damage. This can
result in muscle damage, muscle atrophy and when the wound is finally treated can leave the
horse with large amounts of visible problems particularly if skin grafts are required. The extra
treatment now needed at this stage may lead to further complications such as scare tissue,
which will once again require assistance for a physiotherapist and the use of Ultrasound. The use
of Ultrasound will increase the circulation to the tissues, increase nutrients and flush out toxins
to allow for new healthy tissue to grow.
Due to the nature of proud flesh it is always better to have wounds treated as soon as possible
to prevent the proud flesh producing. However if managed correctly it can be a relatively
straight forward process to treat, however the help from a physiotherapist is key because the
equipment and exercises used to heal the wound, limit further problems and treat any
compensatory factors (muscle tension from transfer of weight etc.) will not only assist the
healing process but will speed it up.