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WOUND H E A L I NG
AUTUMN/WINTER 2011 ISSUE
EQUINE MATTERS
4
7. Re-modelling
This may continue for months after
re-epithelialisation. It improves tissue tensile
strength and reduces the bulk of a scar. At
two weeks after injury, a scar may only have
5 percent of its optimal strength. It may only
reach 80 per cent of normal strength.
6. Regeneration of the blood flow
to a wound.
This is essential to allow the supply of
oxygen and nutrients to a healing wound.
It starts approximately two days after injury.
DAV E ROWL ANDS
There is no way of definitely accelerating wound repair,
but several factors slow down wound healing...
Dressings and bandaging
The wound changes as it heals, and
different dressings are required at different
stages to get the best possible results. A
good dressing will keep the wound slightly
moist but the surrounding skin dry.
Primary wound dressings
such as
dermisol cream, intrasite gel and allevyn
dressings are placed directly in contact
with the wound.
Secondary dressings
support or hold the
primary dressing in place. They provide
support for the injured limb or region. Their
functions include immobilisation, reducing
swelling, reducing pain, protecting the
wound from trauma.
A variety of bandages can be used which
include foot, lower limb, full limb and stent
bandage e.g. for abdominal incisions/
wounds or over areas that are difficult to
bandage normally. Bandage changes
may be required every 2-3 days initially;
reducing to every 3-5 days once the
wound is starting to mature.
A Robert-Jones bandage is a heavily
padded, layered bandage which can be
used for temporary support for a severely
injured limb. It may also be used to treat
wounds that occur in combination with
other injuries to bone or where movement
of the joints needs to be limited. Casts can
also be useful to assist in the healing of
wounds of the lower limb; by preventing
movement of the area they can allow an
optimum rate of healing.
Second intention healing
Many traumatic wounds in the horse have to
be allowed to heal by secondary intention.
This may be due to significant skin loss,
marked contamination, continuous movement,
skin tension or wounds not presented on the
day of injury. Secondary intention healing
usually involves the application of dressings
to assist wound healing.
Factors that affect
wound repair
There is no way of definitely accelerating
wound repair, but several factors slow down
wound healing. These factors need to be
reduced or removed in order to provide an
optimum environment for wound healing.
1.General health status
Malnutrition/debilitation and some diseases
will reduce the rate and quantity of wound
healing. Protein loss (hypoproteinaemia)
reduces wound strength. Deficiencies in Vitamin
C, Magnesium and Zinc will delay healing.
2.Blood supply/anaemia
Reduced blood supply to a wound inhibits the
healing process.
3. Location of the wound
Wounds on the head and trunk generally heal
well. Wounds on the lower limbs of horses
tend to heal poorly. This is because the blood
supply is poor, there is less musculature, more
movement and more contamination.
4. Infection
Bacteria inhibit all phases of wound healing.
Time is a critical factor in the treatment of
wounds and prevention of the establishment of
infection. There is a 'golden period' of 3-5
hours before bacteria reach a critical level to
prevent healing. It is therefore important that
wounds are effectively cleaned using clean
water or saline as soon as possible.
5. Proud flesh
Excessive movement and contamination of
wounds on the lower limb can result in excess
granulation tissue or 'proud flesh' being
formed which halts the healing process. This
needs to be trimmed back and immobilised,
a flat bed of granulation tissue is essential for
epithelialisation to occur.
Other factors that delay wound healing
include; the presence of dead tissue, foreign
bodies e.g. wood, a haematoma (blood
blister) and dead space (a gap between the
skin and underlying tissue), movement and
oedema (swelling).
Types of wound treatment
Primary closure
The wound is closed usually immediately,
and completely, using a strict aseptic
technique, with skin sutures (stitches) or
staples. This is only suitable for clean or
minimally contaminated wounds. Plastic
drains can sometimes be used to reduce
the 'dead space' between skin and
underlying tissue.
Treatment of wounds
Box rest is usually required to minimise the
amount of movement and speed wound
healing in the early stages. Antibiotics and
pain relief may also be required. Where
skin sutures (stitches) have been used, they
are usually removed after 10-14 days.
Skin grafts
These are used commonly in equine
wounds to speed the rate of healing where
the wound covers a large area, especially
on the limbs. 'Pinch' and 'punch' grafts are
the simplest to perform and involve taking
small circles of skin from another area
usually the neck or abdomen. A flat healthy
bed of granulation tissue is needed to
accept the grafts which are placed in small
holes made in the tissue (Figure 1).
Epithelialisation can begin from each
accepted graft and can rapidly speed up
the total healing time (Figures 2 & 3).
Figure 1
Figure 2
Figure 3