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Wound management in the horse (and other animals)

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01 July 2013, at 12:00am

MARTIN JENNINGS of Horseware discusses wound treatment and the use of hypochlorous solutions

HORSES are incredibly prone to traumatic injury. Unfortunately their surrounding environment is rarely clean and it is not possible to subject horses to bed rest.

However, reduction of wound contamination and movement limitation are essential to optimise wound healing and to allow the horse to return to its normal routine and function as quickly as possible.

Wounds of the lower limb, below the knee or hock are the most commonly encountered and often the hardest to treat.

Injuries to synovial structures, such as the digital flexor tendon sheath, and joints – coffin, pastern, fetlock – may not be immediately apparent but must be quickly identified to allow for optimal treatment.

An excessive amount of fluid exiting a wound may signify a synovial structure has been penetrated. Further diagnostics such as x-ray or ultrasound may also confirm a fracture or tendon injury, identify a foreign body or gas in a synovial structure indicating penetration.

Should the patient be excessively lame for the apparent injury then synovial sepsis, a bone fracture or tendon injury should be suspected. Such animals should be referred to allow for further evaluation.

Initial patient management

Upon examination, it is imperative that tetanus is considered; due to the economic downturn vaccinations may be neglected, potentially making this condition more prevalent.

Complete examination of the wound may be aided by peri-neural anaesthesia above the injury prior to clipping, cleaning or prepping the actual wound. The use of mepivacaine (Intraepicaine) is normally recommended to minimise tissue inflammation at the injection site, and has a longer length of activity than lidocaine.

The horse may also require sedation, to facilitate evaluation and treatment. Using xylazine hydrochloride with detomidine hydrochloride and butorphanol tartrate can be helpful in a stressed horse, in order to get quick but long-lasting sedation.

Wound evaluation

When clipping, the use of a gel (KY or intrasite) will reduce further wound contamination.

Cleaning of the wound and surrounding skin would traditionally be performed with dilute povidone iodine or chlorhexidine solution.

Dilution of these products is essential as they are toxic to healthy tissue at high concentrations.

The use of non-woven swabs is recommended, versus woven swabs or cotton wool, as there is less chance of lint deposition in the wound.

Wound lavage is commonly performed with sterile saline or lactated Ringer’s solution with or without pressure using a needle and syringe, dental pik or Versajet in order to remove gross contamination from the injury (such as grass, and dirt).

An alternative to standard wound lavage solutions is a hypochlorous solution such as Hypocare for wound irrigation and debridement. As hypochlorous solutions are non-toxic to healthy tissue and have anti-bacterial, anti-fungal and anti-viral properties, they can be used liberally when performing initial evaluation of the wound, during the cleaning phase and during bandage changes.

During the initial evaluation, the depth of the wound can be determined, and then suitability for primary closure, delayed closure or if the wound should be left to heal by secondary intention.

Wound closure

Primary closure of traumatic wounds is to be aimed for. In the horse, conservation of as much skin as possible is best, in order to reduce the size of the wound to heal. Tension relieving suture patterns, such as cruciate and mattress sutures will aid closure, and the use of non-absorbable monofilament suture is recommended.

Should the limb be very swollen having cleaned the wound, a tight bandage with Vetwrap may be applied for a few minutes or towel clamps placed across the wound prior to suturing in order to reduce the oedema in the limb easing wound closure. Alternatively, placement of large mattress sutures and then replacement of such sutures as they loosen will aid closure.

Wound bandaging

Bandaging post-suturing limits contamination of wounds from the environment. The wound size and location determines whether a horse should be immobilised in a cast or with a splint or whether a multi-layer bandage is sufficient.

Most equine wounds tend to be exudative. Foam wound dressings which “wick” exudate away from the wound but maintain a moist wound environment are therefore very useful.

Normally, at bandage changes wounds will require some degree of cleansing. Again surgical scrub or hypochlorous solutions can be used at bandage changes to reduce bacterial load, which in the clinical case is important to speed wound healing. Hypochlorous solutions such as Hypocare have the benefit of being ready prepared, and easy to use.

Hypocare is balanced at the optimum pH of 5.5, providing an ideal pH environment conducive to healthy tissue generation and efficient wound healing. Because of this skin-neutral pH, it does not sting open wounds and is therefore easy to apply and not stressful for an already distressed animal.

Working naturally with the body, it rapidly destroys the DNA and RNA of pathogens associated with bacterial, viral and fungal infections, making it an excellent choice for speeding up the healing of wounds.

  • For further information see www.horseware.com/hypocare/.