Veterinary traumatology: how to treat open wounds.

Cleaning the wound

Irrigation is an important part of initial wound care, as it flushes out debris, foreign bodies and above all bacteria. In clinical practice, a simple 60 mL syringe with an 18G needle can be used, generating a pressure of approximately 7–8 psi, which is sufficient for most wounds. The most commonly used products are chlorhexidine, povidone-iodine or fluid therapy solutions (preferably Ringer’s lactate). Tap water should be avoided as it is hypotonic and can damage devitalised tissue. Other irrigation solutions are available, such as Prontosan®, which help remove bacteria by reducing the surface tension and therefore making it easier to flush them out.

Regarding debridement, devitalised tissue can be removed by:

• Surgical excision: nonviable tissue should be removed in layers, preserving bone, tendons, nerves and vessels as much as possible. Alternatively, the entire wound can be resected en bloc if it is surrounded by enough healthy tissue.
• Enzymatic debriding agents: useful when the patient has a high anaesthetic risk or as an adjunct to surgical debridement. The most commonly used enzymes are trypsin, deoxyribonuclease and fibrinolysin.
• Wet-to-dry dressings assist with debridement by absorbing necrotic debris and transporting it away from the wound surface as the gauze dries.

Wound disinfection

Contaminated wounds contain microorganisms. Infected wounds can be colonised by microorganisms which then begin to reproduce. Systemic antibiotic therapy should be limited to cases of moderate-to-severe contamination or infection in open wounds that are more than 6–8 hours old, or if there is a risk of septicaemia or disseminated infection, and based on bacterial cultures. In all other cases, topical treatments may be sufficient for good wound management. The most commonly used topical medications are triple antibiotic ointment (bacitracin, polymyxin, neomycin), gentamicin sulphate and nitrofurazone.

Closing wounds

One of the most critical decisions when faced with an open wound on a distal limb is whether to close it or leave it open. An essential factor to consider with distal limbs is the tightness of the skin, which often complicates primary closure in cases of severe tears, leading to the need for skin grafts from other areas.

There are four wound closure modalities:

• Primary closure: immediate stitches.
• Delayed primary closure: 1 to 3 days after injury, but before granulation tissue has appeared and when there is no infection.
• Secondary closure: after the appearance of granulation tissue. Granulation tissue helps control the infection and fills the tissue defects. Skin grafts are a special type of secondary closure if there is no redundant tissue to fill the defect.
• Secondary intention closure: dressings promote granulation tissue formation, contraction and epithelialisation. In many cases it is the best remedy to avoid undesired dehiscence and infections.