AROUND 10 YEARS AGO the Activon range of medical-grade manuka honey was launched into the UK veterinary market to follow the success of many years of successful use in human wound management. Since then, a range of other brands have joined them, all offering the antimicrobial and debridement properties that are a feature of honey. From honey impregnated seaweed to ribbons, foam and gauze there is a dressing available for just about every kind of wound. With many practices now accustomed to using manuka honey for wound management, it seems timely to review its applications and its role in veterinary practice.
From wives’ tales to modern day
Using honey for wounds is nothing new, with its properties extolled over many centuries as an aid to healing and for reducing inflammation. For many a miracle cure, for the more scientific it simply combines properties that aid debridement and decontaminate wounds to aid the smooth progression of healing through the inflammatory phase. Honey (of all types) offers the
wound several benefits due to its “natural” high sugar content, which creates an osmotic effect in the wound, a low pH which inhibits microbial proliferation, and some key enzymes which create an antimicrobial effect similar to that adopted by neutrophils. The more recent research into the specific antimicrobial properties of mono-floral “manuka” (Leptospermum scoparium) derived honey found that its antimicrobial effect is
enhanced by the presence of methylgloxal, a plant-derived phytochemical, which offers a potent antimicrobial effect independent of the pH, enzymes and sugars.
Risk and reward
Despite its potent and evidenced antimicrobial effect, even manuka honey is not immune to contamination by bacterial spores. Pasteurisation is ineffective at inhibiting spores of potentially pathogenic bacteria such as Clostridium botulinum.
- May be used to aid debridement where surgical/anaesthetic risk presents.
- May be used to decontaminate alongside debridement (e.g. with wet to dry).
- May be used to aid removal of foreign body/debris.
- Extensive wounds coupled with shock and high exudate (e.g. severe burns).
- Bleeding wounds.
- Healthy granulating wounds.
- Epithelialising wounds.
Due to the osmotic action of honey, the exudate level in the wound will likely increase during use and an absorbent secondary dressing is required. Use of a barrier cream such as Cavilon (3M) around the wound will help to prevent excoriation to the surrounding skin if exudate levels are high. Manuka honey can be used in wounds with post-surgical dehiscence although it should be considered that dissolvable sutures may break down more rapidly as a result. It is a decision for the clinician based on each wound they are facing and the role the sutures play. If the sutures are achieving little but a foreign body effect, it may be better to remove them and explore what is going on beneath and any application of manuka honey can have maximum contact with the wound bed.
- Tube: for application into cavities and abscesses.
- Dressings: presentations include gauze, alginate sheets and ribbon, hydrocolloid, and impregnated polyurethane foam.
Some DIY tips
Most brands of manuka honey can be diluted by up to 50% while maintaining an antimicrobial effect. This means there are some additional ways it can be used for specific wounds.
- Manuka honey solution – medicalgrade manuka honey squeezed into a syringe with up to 50% warm saline added and shaken to make a solution. This solution can be used to flush into pocketing wounds or beneath areas of dehiscence, or to moisten gauze intended for wet-to-dry application giving a level of antimicrobial and osmotic action.
- Manuka honey gel – medical-grade manuka honey can be mixed up to 50:50 with a hydrogel to create an osmotic gel. This may be particularly helpful for cases of burns or where tissue loss is extensive.
Manuka honey dressings can be left on a wound for around five days, assuming there is honey still available in the dressing during the contact time. The impregnated dressings such as Algivon combine the absorbency of alginate with a high loading of medical-grade manuka honey to create a soft gel that should last several days. Manuka honey from a tube will not last so long, but can be placed into cavities, onto gauze and tied to achieve your own versions to suit the patient. The fact is, each wound is different
depending on the location and the size of the patient (e.g. cat versus horse) so exudate levels vary and wear time will need to be adapted to suit. It would be reasonable to expect the most powerful response to honey to be on the first application when the
osmotic action coincides with a peak in the inflammatory phase and a high level of exudate. Therefore one to two days’ wear time would be realistic combined with an absorbent dressing. As inflammation subsides then the wear time can be increased to up to four days, to which point a healthy granulation bed is achieved. If there is honey left on the dressing on removal, you may well have taken it off a little early; if there is no honey to be seen, you may have gone a little too long.
- Small animal: antimicrobial, for foreign body removal.
- Equine: hoof abscess, and autolytic debridement of wounds.
- Farm: even goats, cows and sheep!
- Tie-over dressings.
- Superabsorbent dressings.
- Medical pet shirts.
Why not use it for everything?
Wound healing is a cycle that is optimised through the phases of healing firstly by aiding debridement during the inflammatory phase (days one to four) and then by maintaining a moist environment to support angiogenesis and fibroplasia that will fill the deficit and enable wound contraction (day four onwards). The high-sugar, low pH environment provided by honey will have a negative impact on fibroblast activity and may contribute to the formation of exuberant granulation. This certainly seems to be the case anecdotally. Once honey has helped to achieve the aims of debridement, it is ideally replaced with a hydrogel that is more sympathetic to the proliferative phase.
The benefits of manuka honey may appear to be miraculous, but it is simply that it does its job of aiding debridement and decontamination very well indeed. As a tool, and not a cure-all, it offers the clinician a way of achieving a less aggressive form of debridement than wet-to-dry or surgical techniques albeit over a longer time frame.