Equine Wound Management Flashcards
Name 4 Types of Wound
Traumatic, Surgical, Chemical, therma, irradiation
How can wound location affect the rate of healing?
- distal limb wounds heal slowly: movement, blood supply, local factors
- wounds on the trunk heal much faster large ability for wound contraction
- also need to consider underlying structures e.g. joints, tendons, bone etc
List the stages of wound healing
Inflammatory Debridement Proliferation: Fibroplasia Proliferation: Epithelialisation Proliferation: Angiogenesis
Describe the inflammatory stage of wound healing
duration and intensity determined by nature of injury
becomes prolonged in the presence of necrotic debris, foreign material or infection
a prolonged inflammatory phase retards long-term healing due to extended proliferation
Describe the Debridement stage of wound healing
often considered as part of inflammatory phase
neutrophils and macrophages phagocytose bacteria and enzymatically remove necrotic tissue
length of this stage depends on the extent of the wound and amount of necrotic tissue
Describe the Proliferation : fibroplasia stage of wound healing
Fibroblasts migrate into the wound along fibrin strands
Healing wound = granulation tissue
Myofibroblasts cause would contration
Describe the Proliferation: Epithelialisation stage of wound healing
very sensitive stage in healing inhibited by infection desiccation of the wound surface exuberant granulation tissue repeated dressing changes slow: estimated rate of 0.2mm/day for flank wounds, 0.09mm/day for limb wounds
Describe the Proliferation: Angiogenesis stage of wound healing
complex series of events involving formation of new capillary bed out of underlying microvasculature
mediated by diverse soluble cytokines and chemotactic agents from serum and ECM
exuberant granulation tissue often characterised by excessive microvasculature
How can a tumour be spread into a wound and what can it be mistaken for?
- Remember: some tumours may appear very similar to granulation tissue
- fibroblastic sarcoids
- haemangiomas
- SCCs
- Can be spread by fly bites so can be inoculated into wound
What 2 factors may you focus on when completing a history for a horse with a wound
- Age of the wound
* Vaccination status of the horse (tetanus is a key one here)
Name three fluids that may be used to clean wounds
- 0.05% chlorhexidine
- 0.1-0.2% povidone iodine solution
- in general isotonic fluids are often a safer choice
- OR just water
Name three conditions associated with wounds which may cause maked lameness in horses
- septic synovial structures
- fractures
- tendon injury
Describe the use of Lavage for wound prep (Include equipment and process)
Can be achieved using 18 gauge needle and 50ml syringe, >15psi forces bacteria deeper into the wound (use of an excessively high pressure can cause further problems
How does a lavage help with wound healing?
• Lavage removes contamination shortens inflammatory and débridement phases
Describe the process of Hydrosurgical Debridement and its uses in wound preparation
- high pressure jet of sterile saline parrallel to the wound surface
- precise and controllable means of cleaning, débriding and preparing the wound
What processes follow cleaning in the preparation of equine wounds?
- Protect wound with water-based gel
- Clip surrounding area
- Palpate area carefully examine for areas of heat, swelling and pain
Describe healthy synovial fluid
- Pale yellow, translucent
- Stringing between fingers
- <1 x 109 nucleated cells/ml
- < 10% neutrophils
- <20 g/l
Describe pathoilogical synovial fluid
- Haemorrhagic, often dark yellow, flocculent material, increased volume
- Reduced viscosity/watery
- > 10 x 109 nucleated cells/ml
- > 80% neutrophils
- > 40 g/l
What adjunctive medication would you give alongside equine wound management
Analgesics - may mask deterioration of clinical signs
Tetanus anti-toxin - provides cover for 4-5 weeks, can be administered concurrently with tetanus
What bacteria is commonly isolated from synovial fluid following iatrogenic sepsis?
Staph. aureus
Name three antibiotics that could be given if synovial sepsis or an open fracture is suspected following an equine wound
- gentamicin (6.6mg/kg)
- penicillin (>10mg/kg)
- Intra-articular aminoglycosides
Describe Halsteads 6 Principles
- Strict asepsis during preparation and surgery
- Good haemostasis to improve conditions for the procedure and limit infection and deadspace
- Minimise tissue trauma
- Use good surgical judgement ensuring elimination of deadspace and adequate removal of material
- Minimise surgery time through knowledge of anatomy and technique
- Correct use of instruments and materials
Describe Primary Wound Closure
Defect closed by apposing and suturing skin margins
provides fastest healing and return to function
In what situations is primary wound closure an option?
Acute wounds where there is minimal trauma and contamination
What effect does bandaging have on primary wound closure
Reduces:
Movement, Contamination, Dead space
Define Debridement
• Remove devitalised tissues, foreign material and bacteria
Describe four methods in which debridement can be achieved
- Sharp dissection most commonly used
- sharp scalpel blade and forceps
- Versajet very useful
- (Osmotic dressings)
- (Wet-to-dry dressings)
Describe drains and when they are useful in equine wound management
- Used when dead space cannot be eliminated
* Should be placed through separate incisions proximal and distal to the wound (reduces risk of infection)
Describe methods by which the infection risk of drains can be reduced
- If drain is exposed it should be covered by a sterile dressing
- Leave in place ideally 48-72 hours
- potential to wick infection
- antibiotic therapy should continue until after drain is removed
Describe three examples of passive drains
- Most simply achieved by leaving a hole adjacent to suture line at a dependent point
- More usually through use of Penrose drains
- fluid moves by capillary action AROUND the drain
- Tube drains sometimes used e.g. thoracic cavity
Describe an active drain
- piece of drip tubing with fenestrations in portion to be left in wound bed
- exterior section connected to three-way tap and 50ml syringe
- suction applied via closed three-way tap; plunger secured by pin drilled through plunger
- can be emptied via three-way tap
Which suture type is best for the blood supply ?
Vertical mattress
Which suture type is better for reducing tension?
Horizontal mattress
Describe delayed primary closure and why it may be used
- Wound closed several days after the injury but before granulation tissue has developed
- initially treated as an open wound to allow débridement and reduce bacterial contamination
What are the properties of a wound that will be treated with delayed primary closure?
- mild to moderate contamination
- minimal tissue loss
- minimal wound tension
Describe the process of secondary intention healing
- Wound cleaned and debrided (then left to heal)
- Apply petroleum jelly to proximal wounds that cannot be bandaged
- Process can be accelerated through the use of skin grafts
- Aim to provide optimal environment for healing
- Moist environment sensitive to granulation tissue and epithelialisation
- BUT need to balance moisture with prevention of bacterial contamination (maintain sterile environment where possible)
Describe the type of wound that would be treated using second intention healing
- heavily contaminated wounds
- high tissue trauma
- extensive dead space
- excessive tissue loss
What treatment method would be used to deal with chemical burn or injuries?
Second intention healing
How can a skin graft improve treatment of areas with skin deficit?
can reduce overall cost and length of treatment
• generally better cosmetic result
• provides new source of epithelial cells
What factors improve success rates of skin grafts?
Beginning with a healthy, confluent (flat) bed of granulation tissue
Minimizing movement after application of grafts
Describe two types of skin graft
Full/split thickness - require expensive equipment, time consuming and require GA
Island Grafts - more useful in large animal surgery
What makes distal limb grafts problematic?
• Distal limb grafts difficult due to the movement of joints and poor vascularisation.
Describe the perfect donor area for tissue to be used in an island graft.
• Choose inconspicuous site with abundant skin tissue
Describe the process if carrying out an Island skin graft
Aseptically prepare
Inverted L-block
For punch grafts attempt to orientate hair follicles
Ideal recipient bed = smooth healthy granulation tissue
(for punch grafts use a smaller biopsy cutting instrument to create recipient areas in wound bed i.e. 8mm instrument to create grafts; insert grafts into 6mm diameter recipient areas in wound bed)
Describe the issue of excessive granulation tissue
- Granulation tissue protrudes above epithelial margins
- low oxygen tension and blood flow
- high motion areas
- chronic contamination/infection
- excess skin tension/over bandaging
- imbalance of inflammatory cytokines
Decsribe proud flesh and how it can be treated
Proud Flesh
(excessive granulation tissue)
• Simplest treatment is resection
• removes tissue and also source of TGF-β1
• granulation tissue has no nerve supply BUT
• animals can still perceive skin tension
• AND high vascularity leads to A LOT of bleeding
Describe the use of topical agents for wound healing
- Corticosteroids reduce production of TGF-β1
- useful after debulking
- BUT high concentrations will impede healing and epithelialisation
Describe the involvement of movement in wound healing
Minimise movement
• animal management
• external co-aptation: cast>splint>RJ
When does inadequate granulation occur? Why ?
Most commonly when there are areas of exposed cortical bone.
Periosteum supplies blood supply to outer 1/3 or cortex
Periosteal stripping renders underlying bone extremely sensitive to infection
No opportunity for attachment of granulation tissue
How would you treat inadequate granulation tissue?
Treatment • Acemannon (Carravet; Carrasorb) • available as a hydrogel • enhances early stages of wound repair by stimulation of macrophages • honey may have a similar effect • Aliginates • promote and maintain tissue hydration
What methods can be used to treat large tissue defects?
- Can use biological scaffolds
- A-Cell: porcine bladder sub-mucosa
- BioSist: porcine intestinal sub-mucosally derived collagen
- provide framework for migration of fibroblasts
- may also provide growth factors
How can Myiasis be used in wound treatment.
- facilitate débridement
* specially prepared larvae of Lucilia sericata
Describe the tree types of cast
- Full-limb/half-limb cast
- always applied under general anaesthesia
- careful application in normal weight-bearing position vital
- a badly applied cast can cause more damage than the wound it was meant to address
- Bandage cast/sleeve cast
- cast material applied as outer layer of bandage
- Foot (slipper) cast
- hoof capsule to PIP or fetlock joint
