No one saw what happened to Gunner in the night. But when his caretaker arrived at the pen one morning in June 2012, the 7-year-old Quarter Horse had a gaping wound on his right hind leg. Apparently, he had somehow gotten his leg caught on a metal guardrail, and in the struggle to free himself he tore off a wide swath of flesh, exposing three inches of cannon bone and damaging nearby tendons. “I thought we were going to have to put him down,” says his owner, Suzanne Huck, a registered veterinary technician at Ohio State University.
Gunner’s veterinarian, Andrea Arbuckle, DVM, of Grenola, Kansas, began treatment with topical antiseptics and other conventional wound-care products. But after two weeks, proud flesh was crowding around the edges of the injury site. “We still had a good inch-and-a-half of cannon bone exposed, and we were thinking he was going to have to have surgery for bone sequestrum,” Arbuckle says.However, one of Arbuckle’s small-animal colleagues told her about a wound treatment they’d used that had shown astonishing results: honey.
Arbuckle did some research on different varieties of food- and medical-grade honeys and brought the suggestion to Huck, who agreed to give it a try. They began treating the wound with manuka honey, a particular type from New Zealand, as well as an ointment for proud flesh. The difference was soon apparent: “Within five days, you had to push really deep to feel the cannon bone, and within two weeks, the wound had filled up to the skin surface,” says Arbuckle. “Also, there was concern about infection in the bone and sequestrum formation, but I think the honey prevented it. It was amazing.”
Honey---yes, the sticky, yellow stuff made by honeybees---has been used to treat wounds since the dawn of civilizations in Egypt, China, Sumer and India, and probably among peoples over the rest of the world as well. But unlike many ancient treatments and folk remedies, honey as a medicine has been standing up to the rigors of contemporary medical research.
In fact, in 2007 the Food and Drug Administration approved a product called Medihoney, the first of several lines of over-the-counter, manuka honey-based gels, ointments and dressings used on burns, pressure sores, diabetic foot ulcers and other skin wounds in people. Researchers are also looking into using honey products to treat many other ailments, including chronic sinus infections, coughs, eye injuries and gastrointestinal issues. Honey even shows promise for fighting MRSA (methicillin-resistant Staphylococcus aureus) and other “super” bacteria that are becoming resistant to antibiotic drugs.
“Honey has always been useful as a medicine, but with modern research identifying honeys with outstanding antibacterial properties and demonstrating its very broad spectrum of activity, honey is becoming important now that the antibiotic era is coming to an end as resistance in bacteria is ever-increasing,” says biochemist Peter Molan, PhD, of the University of Waikato in New Zealand, who has been investigating manuka honey since 1981. “Research is also revealing that honey does much more than clear infection: It actively stimulates the repair process, and its powerful anti-inflammatory activity prevents hypertrophic scarring.”
So the next time you’re stocking up your barn’s medicine chest, along with the leg wraps, gauze and other first-aid basics, you may want to consider adding some medicinal honey to your shopping list.
Not all honeys are the same. That is evident in any well-stocked supermarket, where you’ll find dozens of different jars labeled by the type of flowers the bees drew from---orange blossom, clover, buckwheat, mesquite, thyme, tupelo, lavender, etc.---in a range of shades from dark browns to pale golds. All of these honeys have subtle differences in flavor, but the variations in their chemistries also have implications for medical uses.
The chemical properties of honeys---and exactly how their components behave on wounds---are still under investigation. “Much of how we believe honey works in wounds is still theoretical,” says Patrick Pollock, MRCVS, DECVS, of the University of Glasgow in Scotland. “We do know that it has an antimicrobial effect, we believe it has a debriding effect and an anti-inflammatory effect, and anecdotal evidence suggests that it can be helpful in other ways. But that’s not based on a lot of good science yet. We’re still looking at what honey actually does.”
The primary benefits of honey are its antibacterial, anti-inflammatory and antioxidant actions:
• Antibacterial.Several properties of honey help it kill bacteria. For one, it is acidic: Most honey varieties register between 3.5 and 4 on the pH scale. Animal tissues, in contrast, are slightly basic, with a normal pH in the range of around 7.4, and most bacteria found in wounds thrive best in a neutral to basic environment, with a pH of around 6 to 8. The honey, however, lowers the pH on the surface of the wound to a level that inhibits bacterial growth.
Also, honey is hygroscopic, which means that its sugars readily absorb moisture and will pull it from the surroundings. So honey will draw pus, waste products and other fluids out of the wound while keeping the exposed surfaces moist. This in turn encourages fresh lymphatic fluid to flow into the injured area. Most species of bacteria do not survive in this hygroscopic environment.
Honey produces hydrogen peroxide, a common disinfectant. As part of the honey-making process, bees secrete an enzyme called glucose oxidase into the honey. This enzyme remains stable in its original form in sealed, pure honey. However, once the honey is exposed to oxygen and water, a chemical reaction occurs that releases hydrogen peroxide.
“Hydrogen peroxide can give a high level of antibacterial activity in some honeys,” says Molan, “but on an open wound a lot of that activity is lost as a result of destruction by an enzyme present in the cells of blood and wound tissues.” That is, enzymes present in bodily fluids rapidly break down hydrogen peroxide.Some honeys, especially manuka, also have non-peroxide activity (NPA), which means they retain antibacterial action even if their glucose oxidase/hydrogen peroxide activity is neutralized. Most of the NPA of manuka honey is due to high levels of another compound, methyglyoxal (MGO), as well as other chemical components that have not yet been identified.
• Anti-inflammatory. Although inflammation is a natural part of the body’s response to illness or injury, if it becomes chronic it can stall healing. The MGO in honey, combined with another protein the bees secrete, acts on white blood cells in the tissue to produce an anti-inflammatory effect. This effect has been well documented in clinical trials. For example, people who receive radiation therapy for cancers of the head and neck often experience painful inflammation of the tissues inside the mouth. In one trial, 20 people were asked to hold pure honey in their mouths 15 minutes before, 15 minutes after and six hours after the radiation treatment. Only 20 percent of the honey-treated patients experienced significant inflammation, compared to 75 percent of 20 control patients not given honey.
• Antioxidant. Honey is rich in polyphenols, a class of chemical compounds with an antioxidant effect---that is, they tend to bind with potentially damaging reactive oxygen species (ROS), which are generated as a byproduct of inflammation. In wounds that become chronic, the normal inflammatory process that heals can generate too many ROS, which in turn stimulates additional inflammation, which can become constant and inhibit healing. Honey’s antioxidant qualities can break that cycle and allow healing to proceed.
The differences among honeys
Just about any pure honey will have some medicinal effect from the acidity and hygroscopic action of the sugars. However, there can be huge differences in the amount of the potentially beneficial compounds different varieties contain.
Manuka honey, made from nectars of Leptospermum scoparium (manuka) trees native to New Zealand and parts of Australia, has received the most research attention since Molan began investigating it in 1981. Manuka honey has been found to contain many times more polyphenols and MGOs than other varieties.
Due in part to Molan’s research, Medihoney, the first commercial product approved by a regulatory authority, was released in Australia in 1999, and by 2008 a British company was distributing medical-grade honey products throughout Europe and other countries around the world. In 2007, the FDA approved Medihoney for sale as a medical device in the United States.
All of these products use medical-grade manuka honey, which has been sterilized, is free of contaminants, and has guaranteed levels of therapeutic substances.
You can buy food-grade manuka honey from a grocery store, and sometimes these products, too, are labeled for their biomedical potency---you may see labels that say “bio-active” or MGO plus a number. However, what is inside the jar doesn’t always match what’s on the label. Honey is a natural product, and unless they are sealed in greenhouses, bees don’t always choose the expected flowers.
Surveys have shown that some food honeys labeled as manuka may derive less than 70 percent of their content from actual manuka trees.
Contamination is another concern with supermarket honeys. When Pollock and a team of other researchers from the University of Glasgow set out to investigate the antimicrobial properties of various honeys in 2013, they gathered 29 different types including commercial medical products as well as honeys purchased from supermarkets and directly from beekeepers. All were first cultured for contamination, and 18 were found to be positive for aerobic bacteria or fungi.
“We did this work because we were aware that horse owners might go out to the supermarket and buy honey to use on their horses, and we were concerned that this might not be safe,” says Pollock. “Quite a lot were contaminated with bacteria. So it isn’t safe to go to the supermarket and buy honey for wounds.”
However, Pollock adds, “One positive aspect of this study is, it had been thought that manuka was the most potent antimicrobial honey. But we found a number of others that were equally good if not better at killing microorganisms. Heather honey was especially good at killing bacteria.”
Other researchers, too, are discovering honeys with good therapeutic properties. Tualang honey, derived from the tualang trees in the jungles of Malaysia, was found by researchers at Universiti Sains Malaysia to be higher in phenolics and other compounds and more effective than manuka against gram-negative bacteria, and two other Malaysian honeys---sourwood and longan---were better sources of antioxidants. Researchers from the University of Thessaly found that several Greek and Cypriot honeys performed as well or better than manuka against S. aureus and Pseudomonas aeruginosa bacteria.“What’s especially exciting about this is that a lot of the work that horses do is in the developing world,” says Pollock. “Manuka sells for a massive premium; it’s much more expensive than local honeys. The idea that we could find a local honey and test it for potency to make a cheap and easy wound dressing could benefit a lot of horses all over the world.”
Honey dos and don’ts
In addition to Medihoney, a number of similar manuka honey wound-care products have now been approved for sale in the United States. You’ll find two general types: tubes of gels or pastes that can be applied directly to wounds, and bandages with pads presaturated in medical-grade manuka honey. Either can be used on horses and other animals.
The ointments can be applied to small wounds and left uncovered. Be aware, however, that flies will be attracted to the sugars, and the products are messy. “Everything sticks to it: manure, dirt, straw, hay, shavings and the horse’s hair,” says Renee Andrako of Boise, Idaho, who owns seven horses and has tried honey for minor wounds, sweet itch and cracked udders. Gels combine the honey with a water-based preparation that is less sticky and may be a better choice for a wound that will be left uncovered.
For larger wounds, covering the ointment with a bandage will not only keep it cleaner, it will also help debride the area. Some of the commercial bandages are designed with one layer soaked with honey that overlies a highly absorbent material to draw up the exudates. Plus, the bandaging can help to keep the honey in place.
“It is essential to keep the honey in contact with the wound bed at all times, which means having the honey absorbed in a dressing,” says Molan. “Several brands of wound dressings containing manuka honey are available, or warmed honey can be soaked into an absorbent material. Super-absorbent panty liners make an excellent dressing.”
Numerous controlled studies over the years have shown that manuka honey products accelerate healing and aid healing in chronic wounds in people as well as several animal species. Since treating Gunner, Arbuckle has used honey on other horses, with good results: “The wound takes on a different look with honey than anything else I’ve used before. It’s nice and pink and healthy, and it fills in really fast.”
Nevertheless, Pollock recommends seeking advice from a veterinarian before treating a horse’s wound with honey: “Honey is very helpful in the early stages of wound repair but less helpful in later stages. In the early inflammatory stage, honey seems to have the most positive effect in helping to remove necrotic tissue. But if you are continuing to use honey in the later repair stages, you desiccate the wound, which can be detrimental. As a practitioner, I often see wounds weeks in, after they have become complex and difficult to treat, and there are different directions I would have taken earlier on. So if you’re going to treat a horse’s wound with honey, I would do it with at least some veterinary advice, even if it’s just sending a picture.
”No one has specifically tested whether applying honey to a wound will increase blood sugar levels in insulin-resistant horses. However, says Molan, “Monitoring the level of glucose in the blood in diabetic [human] patients has shown no detectable increase even when honey dressings have been used on open wounds with a large surface area.
”Cave paintings from Spain dating back 8,000 years show people collecting honey---and it’s easy to imagine prehistoric humans using honey for many millennia before that. But this ancient food and medicine is gaining new respect in current medical treatments. In fact, this sticky, sweet treat may once again become the treatment of choice for open wounds, on horses as well as people.
This article first appeared in EQUUS issue #440.