The use of New Zealand’s unique UMF manuka honey is becoming mainstream in wound care in Europe, but still lagging at home. The prime mover in promoting its use is Professor Peter Molan, who heads the Honey Research Unit at the University of Waikato.
Honey has been used for thousands of years as a wound treatment but in recent years has been ‘rediscovered’, triggered to a large degree by the increasing number and virulence of antibiotic-resistant bacteria.
In 1989, an editorial in the Journal of the Royal Society of Medicine expressed the opinion: “The therapeutic potential of uncontaminated, pure honey is grossly underutilised. It is widely available in most communities and although the mechanism of action of several of its properties remains obscure and needs further investigation, the time has now come for conventional medicine to lift the blinds off this ‘traditional remedy’ and give it its due recognition.”
Why manuka honey?
Every honey has antimicrobial properties which help to reduce infection, inflammation, swelling and pain, and hasten tissue repair. The mechanism of action is complicated but revolves around hydrogen peroxide naturally present in the honey. However, some (though not all), New Zealand manuka honey has something special. Early experiments by Professor Molan demonstrated the presence of what is now called ‘Unique Manuka Factor’. The UMF number seen on active honeys is a comparison with a concentration of phenol against a test species of Staph aureus. Thus the higher the UMF number, the greater the antibacterial activity. It is important to recognise that these are non-peroxide, antibacterial components and the label should reflect this.
The discovery and development of UMF manuka honey has made a significant contribution to treatment of wounds but it has been slow to gain acceptance at home.
How should I use it?
Unfortunately, most horse owners will sooner or later have to cope with a lower-limb injury; the inevitable result of mixing wire fencing with horses. The challenges of treating injuries like this are the risk of infection and the development of proud flesh. Both are serious but with proper management can be overcome.
Human medicine has shown the effectiveness of UMF manuka honey in overcoming serious infections, so this is the first approach. Keeping the wound infection-free is the first priority.
The story of the development of specialist honey-impregnated dressings has all the twists and turns of a novel. Unfortunately, the outcome has been that many valuable patents developed in New Zealand have been lost. This may have contributed to the slow development and acceptance of honey dressings by the medical and veterinary professions. The news is not all bad though, as there are now specialist dressings available through Bamford & Co (I have no interest there, but they were helpful in preparing this article).
One of the problems that has been overcome is keeping enough honey in contact with the wound despite the flow of plasma coming from it. Various systems have been developed but the best seems to be an alginate honey mix. The alginate compound is similar to the super-absorbent granules used in disposable nappies. The specially developed film absorbs the excess fluid and at the same time keeps the honey in close contact with the wound.
Treating proud flesh
Exuberant granulation tissue is excessive growth of the granulation tissue which forms to fill in the wound during the healing process. To understand the process we need to understand normal healing.
In the first few days after injury, the wound prepares for healing by removing damaged or dead cells, white blood cells fight infection and fibroblasts begin collagen synthesis. The granulation tissue begins to proliferate, filling in the wound. Granulation tissue has a high density of capillaries, so is red, very fragile and bleeds easily. The skin edges normally contract inwards and heal over the granulation tissue until they meet, forming a scar.
In normal healing, granulation tissue is controlled by inter-cellular communication. The way cells communicate growth information is through contact inhibition or density-dependent growth control. Cells respond to a crowded environment and stop multiplying.
In the environment of a wound there may be a prolonged low-grade inflammation which can lead to proud flesh. Then if the exuberant granulation tissue does not receive the necessary information to stop growth, once it reaches the edge of the skin it continues to rise above the wound edge and proud flesh forms. The skin edges can’t contract over this tissue, which causes the wound to stay open and granulate uncontrollably.
Established proud flesh is traditionally managed by either surgical removal or cauterising, caustic or drying agents applied to destroy the tissue to or just below the wound edge. These methods do not necessarily stop the proud flesh growing and further intervention may be necessary.
A better approach is to prevent the development of proud flesh in the first place.
Over the past 15 years we have developed a protocol that works. In that time we have treated probably one horse a year with wounds that were at risk of developing proud flesh – none has done so.
Early on we used only calendula oil. Historically, calendula has been used in the treatment of wounds, due to its anti-inflammatory, antimicrobial, antifungal, immuno-stimulant, styptic, and granulatory properties.
This was satisfactory, but we felt it would be an improvement – for several reasons – to include manuka honey. The honey provides increased anti-microbial cover, it has anti-inflammatory properties to support those of the calendula and it helps to keep the wound moist.
In the initial phase of healing it is very important to keep the wound infection-free and moist, especially where tendons, ligaments and bone are exposed. As this is a particularly vulnerable time, the addition of honey helps keeps the wound moist until granulation becomes established and covers exposed tissue.
How should I apply it?
We have found the best way is to use a mix of calendula oil and honey at a ratio of about 50:50. Mix it well. In the early days of the wound it is a good idea to spread it on petroleum-jelly-impregnated gauze. It is much easier to remove.
Put this on a piece of gamgee big enough to cover the wound and bandage in place. You may need to re-apply the dressing daily rather than every two days.
The honey used in specially prepared dressings is usually irradiated to ensure sterility. But, according to Peter Molan, in none of the many reports published on the clinical usage of honey on open wounds was the honey sterilised, yet there are no reports of any type of infection resulting from the application of honey to wounds.
The problems of antibiotic resistance will only increase, but we have in New Zealand a fantastic alternative. Unfortunately, it is not used as much as it could be, so next time you have a serious wound to deal with think hard about how you will treat it.
Further information on using manuka honey and the supporting research results can be found at bio.waikato.ac.nz/honey/
- This article was first published in the February 2012 issue of NZ Horse & Pony