Trauma related skin wounds are one of the most common reasons clients require veterinary attention.
The most common wounds usually involve the lower limb and are usually lacerations from kicks, fencing or legs getting caught in gates etc.
It is important to grasp the basic understanding of wound healing in order to make a better judgment call on their management.
Wound healing occurs in 4 phases as follows:
- Immediate response – wound retraction and blood clotting
- Inflammatory phase – bacterial destruction (pus) and wound cleaning
- Proliferative phase – granulation (new tissue forming) and regeneration
- Maturation phase – closure and scar formation
The approach to a skin wound
The first priority is to stop or slow down any notable haemorrhage by usually applying a clean pressure bandage and moving the horse to a cleaner safe environment (if possible). It is important to note here that small innocuous-looking wounds can be very serious and require as much attention as the large dramatic looking wounds.
It is very helpful to the vet that the owner give as much information as possible with regards to how the injury occurred. For example; the horse kicked out at a wooden post, this allows the vet to explore the wound for splinters, or a kick from another horse may result in underlying fracture and lameness.
All wounds should be assessed quickly to determine if significant structures such as joints, tendons, nerves and blood vessels have been damaged.
Restraint
Most skin wounds can be treated under standing sedation and local anaesthesia.
However some more complicated wounds or ones in difficult sites may require a general anaesthetic to achieve the best outcome.
Preparation and wound flushing
Prior to clipping or wound irrigation the wound should be packed with a water soluble jelly such as KY Jelly. This helps to trap hairs and other contaminants including bacteria when clipping or flushing the area surrounding the wound.
It is best to use a warm saline solution for flushing the wound. If saline is not available it is still better to irrigate the wound with water as it will enhance wound healing.
At no stage should any chemicals or acidic solutions be applied to a fresh wound. This significantly damages the tissues and delays healing.
Some examples of essential items for wound management:
Products that can be used as bandaging material: Cotton wool, crepe, quaze swabs, Elastoplast, vet wrap and soffban
Products to use for wound cleaning: Antiseptic wash, saline solution (for rinsing), qauze swabs, and antiseptic spray.
Products to use as a wound ointment: Bactroban, Betadine, Silbercor, Optilube (KY Jelly), Milking cream, Prenine.
A mild antibacterial soap/scrub solution can be used to clean the surrounding areas of the wound.
Cleaning the wound.
It is important to spend time cleaning and preparing the wound at this stage to improve the prognosis for wound healing. Removing necrotic tissue and other contaminants (grass, bedding etc.) in the wound is also paramount to improved healing. This may require sharp (scalpel blade) excision, with the objective being converting an accidental contaminated wound into a surgical one.
The wound can now be explored aseptically (sterile glove or probe) to assess the loss of tissue and other complications involved (joints, tendon sheaths, pockets of contamination etc).
Clean fresh wounds (less than 4 hours old) can be sutured or stapled if there is little tension on the wound edges (primary wound closure).
A fresh wound to a horse’s chest.
Wound after it has been stapled.
A wound that has been sutured.
In the case of degloving and more extensive injuries blood supply to the flap may be severely compromised and the tissue will die off in time. These wounds require healing by second intention (open wound healing and management). Typical example is the inverted “V” injury.
Degloving of the lower limbs.
Bandaging promotes healing by providing a moist environment. It also controls haemorrhage, swelling and excessive granulation tissue. Please note that a good bandaging technique is essential as “over tight” bandaging may lead to severe complications.
Figures above and below showing bandaged wounds
Complications associated with wounds
Septic Arthritis
Joint infection is the most serious complication following traumatic wounds and must be recognized immediately.
Penetrating wounds near the hock and fetlock joints are at higher risk of involving the joints. These wounds should be explored thoroughly. If a joint is involved a yellow thick fluid may exude from the wound. In these cases surgical arthroscopic flushing of the joint may be required. If there is doubt regarding joint involvement, heavy antibiotic cover should be implemented and the joint monitored closely for swelling and lameness.
Septic Arthritis.
Tendons
Extensor tendons (over front of canon bone) are often involved with traumatic skin wounds. Complete severance may result in knuckling at the fetlock but the horse usually will adapt and normal function will likely be restored. Involvement of the Flexor tendons (back of the canon) are far more serious. Usually severance of these produces a lack of support to the fetlock with toe lifting. This holds poor prognosis to salvage the horse.
The result of the severance of the flexor tendon. Note the lack of support to the fetlock causing toe lifting.
Tendon sheaths
Penetration to the tendon sheath can be life threatening and result in chronic lameness. Traumatic injuries at the pastern level have a very poor prognosis and immediate hospital care and emergency flushing is prescribed.
Traumatic injury at pastern level
This diagram illustrates the complexity of important structures in the “pastern area” such as digital flexor tendons & the surrounding tendon sheath.
Bone
If bone is exposed at the wound site, the periosteum (bone covering), may be damaged. This can, in time (weeks to several months post injury), develop into a sequestrum (dead piece of bone causing a chronic infection). This is often manifested by a non-healing wound and can be recognized with radiographs. Surgical removal of the sequestrum has a favourable prognosis. Fractures are also complications associated with wounds and radiographs should be taken if the horse has an associated lameness.
Bone exposed at the wound site.
Proud flesh
Proud flesh is the overgrowth of normal granulation tissue. Lower limb wounds are more prone to develop proud flesh and this usually occurs if there is chronic bacterial infection, excessive movement at the wound site or if minimal or no wound contraction occurs.
Proud flesh. Both above and below.
Preventing excessive granulation may require antibiotic therapy, corticosteroid creams and limiting movement in the form of a cast over the wound or box rest and bandaging.
Excessive proud flesh needs to be surgically removed either standing (under local anaesthetic) or under GA (general anaesthetic) in order for the wound to heal completely.
Excessive proud flesh removed surgically.
Skin grafts
Some wounds may not always close over or form a scar. These wounds may require a skin graft in order to stimulate new hair growth. This often means taking a few biopsies from another part of the horse (often the neck) and placing them in the wound bed.
Biopsies taken from the horse’s neck to be used elsewhere.
Skin graft on the injured area.
A well healed injury with compliments of a skin graft.
Summary
A fair knowledge of the types of wounds and the healing process help the owner to apply basic principles immediately while awaiting veterinary assistance. Each wound should be assed thoroughly and further diagnostics may be required in order to attain the best results possible in the wound healing process.
Keep a look out for our interactive talk where we go into more detail and advice on wound management for your horses and the products to use.
