Jo Hatcher, Cert IV VN, TAE, DVN, AVN; M. Oleary
Classification of Wounds
The appropriate treatment of a wound is dictated by the condition of the tissue at time of presentation. Wounds are classified in the following manner:
Example - Planned surgical incision:
- A ‘clean’ wound is a relatively non-traumatic surgical wound, made under controlled conditions, aseptic preparation, minimal trauma and in a very clean or sterile environment.
- ‘Clean’ wounds are sutured soon after they have been created.
- Incisions entering the oropharynx, urogenital, respiratory or alimentary tract are not classed as clean wounds.
Example - Laceration less than a few hours old:
- There is some trauma to the tissues and the conditions are non-sterile.
- The wound is contaminated with environmental bacteria—either from the object causing the wound or from the normal flora of the animal.
- These wounds are able to be cleaned and sutured if they are presented before the bacteria has had chance to proliferate the tissue, known as the ‘golden period.’
Example - Degloving from road traffic accident:
- The wound is clearly soiled or contaminated with bacteria.
- It has often been exposed for longer than 6–8 h.
- This type of wound often requires aggressive cleaning and staged treatment techniques to facilitate an uncomplicated healing.
Example - Cat fight abscess:
- Also termed ‘infected’ wounds.
- An abscess has formed as a result of infection.
- A wound care plan should be implemented for each individual wound depending on its cause and classification.
Types of Wounds
The cause and type of the wound is a major factor in the treatment technique and long-term plan. They can be initially classified as open or closed.
- Burns and scalds
- Caused by sharp cutting instruments: knives, glass.
- Edges are clean cut and defined.
- Generally, the wound will gape open.
- The wound is usually quite deep.
- The wound can be of any size.
- Generally caused by road accidents, dog-fights, tearing by barbed wire, etc.
- Wounds are irregular in shape and generally gape open.
- Edges are jagged.
- Will usually be contaminated: dirt, debris, etc.
- Very painful.
- Caused by small sharp pointed objects: fish hook, cat’s teeth.
- Small wound—can easily be overlooked.
- Generally, causes a deep wound—tracks down through tissues.
- Also known as ‘grazes.’
- Caused by such incidents as road traffic accidents and animal is dragged along the ground.
- Wound does not penetrate the whole of the skins thickness—it is superficial, can be of any size.
- Very painful.
- Wound is generally contaminated.
The initial goals of wound care are to prevent contamination and protect the tissues. On presentation the wound should be covered. Saline soaked swabs are effective to prevent contamination but also protect exposed tissue from drying.
The hair surrounding the wound should be clipped. Hair should be prevented from entering the wound. Instilling sterile gel into the wound prior to clipping should prevent this. The sterile gel can then be flushed from the wound with sterile saline once the clip is completed.
The wound should be lavaged with fluids under moderate pressure to remove debris and bacteria. Warm isotonic solutions (0.9% NaCl) are preferred. Hypertonic solutions may be used if oedema is present.
Antiseptics and soaps are not recommended, as they are irritating to the tissues and delay healing. However, to reduce bacteria a very dilute chlorhexidine or povidone-iodine solution may be used.
Debridement of necrotic or devitalised tissue may be required to enhance healing. It may be performed layer-by-layer or a large excision in one area. The wound should be surgically prepared, placing sterile gel in the wound during preparation so prep solutions do not enter the area. Once debridement is performed, the closure method may be decided.
Closure may be performed (depending on the type of wound) by suturing the wound. It may be necessary to delay wound suture until further debridement’s are performed. If the wound cannot be closed then healing takes place by second intention.
Drains may be placed in the wound. They are generally made of flexible nonabsorbable tubing. They are placed to:
- Establish drainage of fluids from ‘dead’ space.
- Prevent accumulation of fluids or exudates in the wound.
- Maintain drainage of fluids during the debridement stage of healing.
- Drain exudates from an infected wound.
There are many types of dressings or gels available to promote wound healing. They are the primary part of the bandage applied to the wound.
The type of dressing or gel used depends upon the current stage of healing and the objective of the wound treatment.
- For infected wounds use dressings that reduce the bacterial load (e.g., Acticoat™, Iodosorb™). Use in conjunction with systemic antibiotics.
- For wounds with heavy exudate, use dressings that lift the discharge away from the wound and store it in the dressing (e.g., Allevyn™, Absorb Plus™).
- For dry wounds which are at risk of desiccation, use dressings which restore moisture balance (Duoderm™, Instrasite Gel™, sterile saline soaked swabs).
There are several stages of healing that occur sequentially over a period of time. The healing may occur at different rates in various areas of the same wound.
Stages of Healing
Divided into the following phases:
Six to eight hours post wound occurring:
- Immediate vasoconstriction and then vasodilation.
- Clot is formed at the site of the injury to prevent further haemorrhage.
- Plasma like fluid is produced to assist healing.
- Erythema, heat, swelling and pain develop.
Six hours to 5 days post wound occurring:
- Cellular activity is stimulated by the inflammatory process.
- This results in the production of exudates and discharge from the wound.
- The discharge has a cleansing effect as necrotic debris, white blood cells and tissue fluids are removed with the discharge.
- Discharge = ‘pus’ which can be sterile or indicative of a bacterial infection.
- Performing cytology and looking at the discharge can determine proper wound care.
Starting 3–5 days post wound occurring and lasting 3–12 days:
- Blood vessels grow into the wound.
- Granulation tissue forms to fill the wound area and epithelium begins to form along the edge of the wound.
- Collagen is laid down to give the wound strength.
- The wound becomes smaller in diameter as the granulation tissue starts to contract.
- Healthy granulation is red and shiny; it bleeds easily but is not painful.
Begins 17–20 days post wound occurring and can last up to 2 years:
- This is when the collagen fibres in the connective tissue become replaced and realigned to give the area greater strength. The scar becomes pale and less obvious.
Very little strength during the inflammatory and debridement stages.
During the repair and maturation phase the wound strength starts to increase.
As the scar matures during the later maturation stage the strength will increase, but the final strength of the area is about 20% weaker than the original tissue.
Factors in Wound Healing
Wound healing can be influenced not only by the type and depth of contamination (if present) but also the condition of the patient.
In order for healing to take place efficiently it is essential that:
- The area has a good blood supply. Functioning white blood cells, fibrinogen and numerous other substances need to get to the area. Debris and waste products need to be removed. Oxygen is needed by all the cells to function well.
- There is a good supply of the materials needed to conduct the repair.
Many factors that delay wound healing involves interference with the above two factors.
Wound factors that delay healing include:
- Poor blood supply—fails to carry healing cells, chemicals and oxygen to the areas as well as waste products and debris away from the area.
- Dead space with accumulation of fluid—interferes with local blood supply.
- Infection—negatively affects white blood cell function.
- Foreign bodies or debris present—creates a persistent infection.
- Oedema—interferes with blood supply.
Patient factors that can delay healing include:
- Age (geriatric)—reduced circulation and immune function.
- Systemic disease (diabetes, liver or renal dysfunction) reduced immune function.
- Obesity—impaired circulation.
- Malnutrition (low protein levels)—poor supply of repair materials.
- Cancer and cancer treatments—reduced immune function.
- Some medications—reduced immune function.
- Self-trauma—impairs local blood supply.
Wound Healing Complications
Recognising wound complications can assist in appropriate treatment being implemented as soon as possible. Complications may include:
- The area becomes puffy or spongy and pale in colour. It may produce a watery fluid. When pressed gently with the finger an imprint may be left for a few moments—this is called pitting oedema.
- Devitalised tissue
- If the tissue displays an abnormal colouring such as purple, grey, white, green or black—the area is becoming devitalized. This means that the blood supply to the tissue is decreased or absent. The devitalized tissue will undergo necrosis and may liquefy or become dry and leathery. When the tissue becomes black and leathery, this is termed ‘eschar.’
- This occurs when the wound repair breaks down and the wound becomes open again.
- ‘Proud’ flesh
- Also termed exuberant granulation, this occurs when the granulation tissue is above the level of the skin edges.
- The wound will discharge an odorous exudate, with inflammation at the site and bacteria contained within the fluid.
- Fluid accumulation at the wound site. A fluctuant swelling or mass containing fluid is palpable at the site. This can be a seroma, haematoma or abscess. A fine needle aspirate would be required to determine the type of fluid and treatment course.
- This is a persistent non-healing opening that often produces exudates.
- Contracture deformity
- This most often occurs when a wound is around or near a joint. As the wound contracts and undergoes maturation, the scar tissue may restrict the range of movement.
- Hypertrophic Scar
- Over time the scar should become less obvious, however, a hypertrophic scar will become more obvious appearing raised, thickened and prominent.
The general objectives of a bandage are to:
Provide support for:
- Sprains, strains the fractures
- Further injury
- Stop haemorrhage
- Prevent or control swelling
Provide comfort and pain relief:
- Limit joint movement
- Limit movement of fracture sites
A basic bandaging formula is:
- Initial layer—dressing (applied directly over the wound).
- Primary layer—padding (for comfort, support and absorption of any exudate).
- Secondary layer—conforming (provides strength and conforms to the contours of limb and secures dressing and padding).
- Tertiary layer—protection (protects the bandage and provides further security).
Types of dressings - initial layer
Sterile plain gauze swabs
E.g., with petroleum gel or antibiotic
Usually have a layer of permeable non-stick material on one or both sides. May have absorbent core. Some have adhesive section around the edge to enable stable and accurate placement of dressing.
Melolin® Cutiplast® Cutilin®
These can be made of various materials and are usually quite thick—used for wounds with large amount of exudate.
Types of padding - primary layer
Natural or man-made.
Cotton wool rolls
Natural absorbent material supplied in rolls.
Great for limbs.
Velband® Soffban Natural ®
Thinner and lighter than padding bandage and cotton wool.
Cotton wool and gauze
Cotton wool that is sandwiched between layers of gauze and supplied in a roll.
Types of conforming bandage - secondary layer
Has an elastic component to enable ‘conformation.’
Care must be taken not to apply too tightly.
Has no elastic component loose weave assists with bandage conforming.
Washable cotton fibre on a role not commonly used.
Elastic net bandage supplied in tubular format.
Thick, cotton-based material with an adhesive side.
Material containing latex that ‘sticks’ to itself but not to the skin or hair.
When the bandage has been placed, regardless of the type or area, it should be assessed using the following questions:
- Is the bandage achieving its aim?
- Immobilising the correct joint, not slipping, in correct position.
- Is the bandage comfortable?
- Check that the bandage is not too tight or causing discomfort to the patient—no chewing or interference from patient.
- Is the bandage suitable?
- The bandage is not interfering with the other general movement of the patient.
Once a bandage has been applied and assessed it should be frequently checked until removal, this includes:
- Ensure the bandage is not too tight
- Check that it is not causing the patient discomfort/pain
- Check in correct position (not slipped)
- Check for:
- The bandage should be removed and the source investigated.
- Check above and below the bandage for:
- Skin inflammation/redness
- Heat or coldness
It is vital that the bandage is kept clean and does not become soiled or wet from environmental factors (urine, faeces, wet ground, etc.). If soiling occurs the bandage must be changed.
If a limb is bandaged, the bandage can be protected from the environment (e.g., when toileting outside) by placing a protective covering over it. For example, a clean dry used drip bag can have the bottom cut from it and tied over bandage or use a plastic bag in a similar manner.