EQUINE VETERINARY EDUCATION / AE / JANUARY 2020


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Case 2 A 20-year-old Quarter Horse mare presented to the hospital for an open, draining subcutaneous olecranon bursitis of the right forelimb that had been present and increasing in size over several years. The bursitis was not noted to have been opened or drained but rather developed an associated wound from trauma due to being swollen and protruding (Fig 1). The mare was in good general health and no lameness was present. The distal limb was not swollen. The open wound of the subcutaneous olecranon bursa was 15 cm by 10 cm in size with exposed necrotic tissue and purulent drainage.


Case 3 A 17-year-old Warmblood mare presented for an infected subcutaneous olecranon bursitis that had been opened and drained by the referring veterinarian several months previously. The opening had gradually enlarged and failed to heal. On presentation there was a 10 cm by 10 cm enlargement of the olecranon bursa and surrounding skin with an open wound in the skin of 3 cm by 5 cm on the palmar aspect with necrotic tissue and purulent drainage. No overt lameness was present and the distal limb was not swollen.


Surgery In all three cases the skin and tissue surrounding the olecranon bursa was thickened, indurated, and firm. The open wounds in the skin were large and this, combined with the inelastic nature of the skin, eliminated the possibility to perform a neat lateral surgical excision and primary closure (Honnas et al. 1995). However, the fact that the subcutaneous olecranon bursitis had caused a gradual enlargement of the bursa and overlying skin dictated that


surgical excision was necessary to prevent recurrent trauma and to foster a healing response. All horses had been treated at home for several months with standard wound care by the referring veterinarians and in all cases the infected bursa had continued to enlarge. All horses were administered systemic broad spectrum anti-inflammatory


antimicrobials and medications


immediately prior to surgery and these were continued for 3 days post-operatively. Antimicrobicals were administered to prevent bacteraemia from manipulation of chronically infected tissues and to limit reinfection of healthy underlying tissue. Intravenous sedation for standing surgery was administered and an inverted U block with 2% lidocaine injected subcutaneously was performed proximally and to either side of the bursa. The infected tissue and skin were then resected preserving as much healthy skin as possible but excising all of the infected tissue. In all three cases the skin was initially opposed proximally with a small opening left for drainage ventrally and a stent bandage applied. Horses were then kept on box rest and the stent bandage was changed every 2 days. Substantial purulent exudate was noted at the time of bandage change in all cases with potential maceration of the wound edges. In all three cases the suture line dehisced at 5–7 days and the skin retracted open once more. The result was an open circular wound with a concavity in the interior where all the abnormal tissue had been removed. Negative pressure wound therapy was then applied to all


three horses in an attempt to improve and shorten the healing time. The skin surrounding the surgical sites had already been clipped for surgery but was reclipped and shaved to remove all the hair to facilitate a secure attachment of the apparatus to the skin. The wound was cleaned and a silver impregnated foam (V.A.C. granufoam silverTM


)1 was cut to the size of the wound and inserted into


the wound. The surrounding skin was then sprayed with an adhesive spray (Vi-Drape)2 and the adhesive drape applied to seal the area. A small hole was then cut in the adhesive drape over the foam and the suction cup and tubing applied (Fig 2). The tubing was then attached to the vacuum pump unit (V.A.C. TracPadTM


, V.A.C. Freedom)1 and the


suction turned on. If a seal had not been obtained, additional adhesive drape was applied to the site. The vacuum pump and canister were suspended from a ceiling hook that was usually employed for fluid therapy administration (Fig 3). Horses were monitored and maintained


on continuous therapy at 125 mmHg for the first 24 h and then intermittent therapy with 5 min on, 2 min off, with a


negative pressure of 125 mmHg for the remainder of the therapy. The dressing was changed every 3–4 days until the wound had filled in with healthy granulation tissue to the level of the skin. Sedation was not required for bandage changes. The subjective impression was that all wounds started with a small amount of superficial infection post-surgery as noted by purulent drainage on the stent bandages and this improved rapidly with the NPWT therapy. At the time of the first bandage change at 3–4 days the wounds had healthy, red granulation tissue present. No irritation of the surrounding healthy skin was noted during therapy.


Fig 1: The enlarged olecranon bursa of Horse 2. The open draining portion was directly palmar and therefore not visualised in this picture.


Outcome All horses tolerated the NPWT very well. No discomfort was noted during use and horses moved freely around the stall.


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