46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
83
Managing Distal Limb
Wounds – Is there Anything
New?
Christine Smith DVM, Diplomate ACVS, Agnes Banks Equine Clinic, 5 Price Lane, Agnes
Banks, NSW 2753 Australia
Wound healing is a complex series of temporally and spatially organized events.
Distal limb wounds in horses occur relatively frequently. Contamination, minimal
soft tissue protection, and the potential involvement of important structures such as
synovial structures, neurovascular tissue, tendinous and ligamentous support
structures complicate the picture further. Other factors, which will influence rate
and quality of healing, include location of the wound, tension, wound configuration
and chronicity. It is well established that distal limb wounds in horses heal more
slowly than trunk wounds for a variety of reasons. These factors include a
prolonged and weaker initial inflammatory phase and irregularities in the
concentrations of the different TGFβ isomers often resulting in the persistence of
granulation tissue within the healing tissues. Other factors contributing to slower
healing in equine limbs include slower wound contraction, weaker epithelialization,
as well as impaired blood supply, inflammatory mediator imbalance and low oxygen
tension.1 Some wounds, including those in the heel region and high motion areas will
heal faster with cast coaptation. The application of a foot cast, and lower limb casts
placed in the standing patient should be considered if motion is anticipated to
contribute to delayed healing. Although the frequency of cast complications is
relatively high,2 with expedient use and careful cast monitoring casts can improve the
cosmetic and functional outcome of lacerations of the distal limb, and often decrease
healing time.
The involvement of synovial structures can complicate the treatment, increase the
morbidity and substantially decrease the prognosis associated with distal limb
wounds. Careful assessment of the wound is important to identify any possible
communication with joints, tendon sheaths and bursae. Aseptic preparation of the
synovial structure in question followed by insertion of a needle into the structure
away from the wound allows for collection of synovial fluid for culture and cytology.
The synovial structure is then distended with sterile isotonic fluid and the wound is
watched carefully for leakage of fluid, suggesting communication. Additional ways of
determining whether a synovial structure is involved include careful palpation of the
cleaned wound with a gloved hand. It is possible to overlook small breaches of the
joint capsule using this method however. Contrast radiographs can be helpful. The
contrast material can either be injected into the synovial structure in question, or it
can be injected into the wound bed. Injecting the contrast into the wound bed can
be misleading if there is considerable debris and granulation tissue already present in
the wound bed. Ultrasound evaluation can be helpful in many cases. In most acute
wounds subcutaneous air from the wound interferes with the ultrasonographic
image making interpretation difficult. Ultrasound can however be useful for
evaluating more chronic infections especially involving tendon sheaths. Sampling the
fluid is always optimal in these chronic cases if at all possible. The method of choice
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