Equine wounds Flashcards
Classification of wounds
a) Mechanical injuries
b) Thermal injuries
c) Chemical injuries
a)
- Most common
- Grazes, abrasions, erosions
- Bruising, hematomas, contusions
- Puncture/penetrating wounds
- Lacerations/incised wounds
b)
- Rare
- Thermal burns
- Friction rubs
c)
- Acids: cause coagulation necrosis and protein precipitation
- Alkalis: cause liquefaction necrosis
Classification of wounds
a) Clean
b) Clean contaminated
c) Contaminated
d) Dirty
a)
- Elective/Surgical wounds created under aseptic conditions, primarily closed
- No break in technique or dirty space entered
b)
- GI, respiratory or urogenital tract (without urinary
infection) entered without significant contamination
- Or minor break in aseptic technique
c)
- Traumatic wounds = always contaminated
- elective procedure with major break in aeptic technique
d)
- > 1x10^5 bacteria
- Traumatic wound with devitalized tissues, FB, feces, chronic wound
Stages of wound healing
a) Inflammatory/debridement
b) Proliferative repair
c) Maturation/remodelling
a)
- haemostasis/acute inflammation
- Immediate, lasts days to weeks
- Neutrophils (remove damaged tissue and chemo attractants) and Macrophages (release O2 radicals, cytokines, tissue growth factors)
b)
- tissue formation
- day 3-14+
- angiogenesis, fibrous and granulation tissue formation
- collagen deposition
- epithelialisation
c)
- strengthening tissue
- ends in formation of scar tissue
Control of haemorrhage
- Horse can use ~5L without any real problems
- Pressure bandage
- Pressure with swab/hand
- Topical haemostatic agent
Preparing the wound
- Clip around area
- Clean/lavage with large volumes, moderate pressure (do not use soap solutions)
- Can use local anaesthetic directly on wound to desensitise
- use sterile gloves to palpate
- debride necrotic tissue, but any tissue that may be viable should be left
Wound closure
a) Primary closure
b) Delayed primary closure
c) Delayed secondary closure
a)
- clean wounds with minimal contamination
- minimal tissue loss
- best cosmetic result
b)
- up to 5 days, gives more time for contamination removal
- lavage and dress daily until healthy granulation bed present, then close
c)
- rarely performed due to lack of elasticity of skin
Second intention healing
- very common
- especially if contaminated tissue or large skin defects
- granulation then epithelialisation, wound will be exudative
- multiple bandage changes
Suture material used on equine skin
- prolene is least reactive, most commonly used
- can also use nylon, PDS, vicryl
- consider absorbable sutures
Factors affecting wound healing (5)
- Degree of contamination/infection (may need to debride further, broad spectrum antibiotics, allow drainage)
- Tension of skin edges (can cause dehiscence or necrosis at wound margin)
- Vascularity
- Dead space (allows fluid accumulation, use a penrose drain, mesh skin)
- Motion (commonly over joints, must box rest)
Bandaging
a) How often to change a bandage
b) Other materials to use
a)
- typically daily, then reduce it after a week
- depends per case
b)
- clean, dry, sutured wound won’t need anything
- no oil-based ointments, no caustic agents
- flamazine (antibacterial)
- manuka honey (infected wounds)
- topical antibiotics (rarely used, only for chronically infected wounds)
- corticosteroids (chronic wounds, use sparingly)
Bandaging
a) Primary layer
b) Secondary layer
c) Tertiary layer
a)
- wicks exudate
- cushions/protects
- promotes healing environment
b)
- absorbs excess exudate
- provides pressure and support
- reduces movement of wound edges
c)
- secures other components
- provides additional support and pressure
Considerations at
a) Heel bulb laceration
b) Coronary band laceration
a)
- must rule out coffin joint, DDFT and navicular bursa involvement
- primary or delayed primary closure best
- hoof cast reduces movement and allows faster healing
b)
- if coronary band misaligned will result in hoof wall defects
- also use hoof cast
Causes of chronic/non-healing wounds (5)
- excess movement
- large skin defect (may require skin graft)
- presence of foreign body/necrotic tissue (stake wounds, inadequately debrided, bone fragment remaining, bony sequestrum formation)
- excessive granulation (proud flesh)
- systemic disease of patient, quite severe (nutritional status, cushings/PPID)
Chronic/non-healing wounds
Proudflesh indications and predisposing factors
- When granulation tissue protrudes higher than wound edge, difficult for epithelium to grow over
- due to inefficient acute inflammatory phase and protracted chronic inflammatory response (too much granulation tissue)
- trim off tissue until a flat surface
- Predisposing: chronic inflammation, motion, bandages/casts, size of horse
Chronic/non-healing wound
Bony sequestrae cause
- following when initial injury traumatises bone or blood supply to the bone
- suspect when see a mature granulation bed but a cleft/cloaca
- may require surgical intervention
Skin grafting
a) When to use
b) Two types
a)
- speed up healing
- may be less expensive than lengthy bandaging
b)
- Pedicle graft (has vascular and nerve supply)
- Free graft (no vascular/nerve supply, must establish new vascular connections
Skin grafts - free grafts
a) Categories
b) reasons for failure
a)
- Full thickness: epidermis and entire dermis
- split thickness: epidermis and only a portion of dermis
- sheet grafts/ pinch/punch/tunnel grafts
b)
- fluid accumulation
- movement
- infection (must effectively prepare recipient bed)
Pinch/punch grafts
- pinch: small discs of skin harvested using scalpel
- punch: full-thickness plugs harvested with biopsy tool and implanted into granulation tissue using another biopsy tool
- donor site typically taken from neck beneath mane, ventral abdomen
- grafts inserted into holes, cover with a non-adherent dressing and bandage
- leave on for 5 days, then change every 2-4 days
- survival of 60-75% grafts expected
Skin grafts
a) tunnel graft
b) split thickness graft
c) full-thickness sheet graft
a)
- useful for large skin defects or sites are difficult to bandage
b)
- very painful, usually requires GA
- needs specialist equipment
- accepted better than full-thickness grafts
c)
- not accepted as readilt as split-thickness
- epidermis usually sloughs
Synovial sepsis
a) gold standard treatment
b) when to use just needle lavage
c) Common causes
a) Arthroscopic lavage under general anaesthesia (89% survival, 69% return to work)
b) Only on low budget cases (very poor survival rate)
c) Penetrating traumatic injury causing contamination of synovial cavity. Causes marked inflammatory response
Synovial sepsis aetiology
a) Penetrating traumatic injury
b) Hematogenous spread of local/systemic infection to bone/synovial structures
a)
- common in adults, introduction of bacteria via wound
- distal limb joints and tendon sheaths commonly affected
- variable lameness: typically go lame 24-48 hours after injury
- Many bacteria can cause
b)
- occurs in foals (especially immunocompromised or systemic illness - like pneumonia, colitis, umbilical infection)
- lameness may vary, most common clinical sign is joint distension
- Most commonly caused by Streptococcus, Rhodococcus, Actinobacillus, E. coli, Salmonella
Synovial sepsis aetiology
a) Iatrogenic infection
b) Extension of local infection
a)
- infection post injection or surgery
- occurs infrequently
- usually acute lameness and history of joint injection
- Osten involves Staphylococcus
b)
- Rare
- can be due to peri-synovial abcesses, cellulitis
- treat with broad spectrum antibiotics (doxycycline or penicillin/gentamicin)
Diagnosing synovial sepsis
Synoviocentesis
- collection of synovial fluid, number 1 test for diagnosis no matter the aetiology
- fluid analysis (WBC count, % neutrophils and TP most important)
- culture and sensitivity (often not performed as takes days to get result)
Synovial sepsis treatement
- must be rapid and aggressive (immediately refer)
- synovial lavage to remove foreign material, organic debris, bacteria
- systemic antibiotics (penicillin/gentamycin or oxytetracycline - but not for foals)
- local antibiotics usually injected after lavage (aminoglycosides ie gentamicin or amikacin)
- IV regional limb perfusion
a) Specific synovial structures known to have worse outcomes (5)
b) Long-term possibility
a)
- Coffin joint
- Navicular bursa
- Calcaneal bursa
- Tarsocural joint
- Digital flexor tendon sheath
b)
- osteoarthritis, especially in prolongued treatment
