The Science of Wound Ointments for Horses

Your horse comes in from the pasture with a small cut on his chest. Maybe he hit the fence while playing or perhaps it was a tree.

In any case, the wound is fresh, clean and small. No need to call the veterinarian--you can handle this yourself. You reach for a tube of the thick wound ointment you've always used and smear a good-sized glob across the cut. That'll take care of it. Or will it?

Perhaps, says researcher Georgie Hollis, BSc, MVWHA, but it depends on what's in the tube.

The right preparation applied at the right time can protect a wound, support natural healing processes and minimize the risk of complications. But, warns Hollis, use the wrong type at the wrong time and you could actually slow down or even halt healing.

For the past three years, Hollis has been working to help make choosing the right ointment for each situation easier. A former podiatrist, she first observed the challenges of wound healing when she treated foot lesions in diabetic patients. In late 2006, Hollis, motivated by her personal interest in animals and horses in particular, began studying veterinary wound care. She now works with leading equine researchers, such as the University of Liverpool's Derek Knottenbelt, DVMS, MRCVS, in investigating and sharing information about how various treatment techniques affect healing.

Through her program, Intelligent Wound Care, Hollis maintains the Veterinary Wound Library, a database of individual research cases accessible to veterinarians. "There is quite a bit of science out there." says Hollis. "But there is also a tendency, even by veterinarians, to just put anything on the wound in the hopes that it helps. And there is no doubt that part of wound dressing is psychological. The creams cover up nasty-looking skin and make you feel that you've helped your horse in some way. I know as a horse owner, my first instinct is to cover my horse's minor scabs with a nice cream."

In the end, however, Hollis relies on her knowledge of the wound healing process to guide her selections. Here's what she has learned about how to use wound ointments to encourage healing.

A Fresh Start
The first step in treating any wound is a good cleansing. "Dilution is the solution to pollution," Hollis says. "Flushing the wound with large quantities of warm saline or water will loosen debris and dilute the bacterial concentration within the wound. This process alone is one of the most useful things an owner can do in helping a wound to heal."

Wounds that are particularly dirty may also benefit from antimicrobial wound washes, such as those containing povidone iodine or chlorhexidine, which kill bacteria on the surface of the wound while cleaning it (see "The Antibiotic Question" at the end). But small, fresh wounds often require nothing more than a standard cleansing, which removes bacteria mechanically.

As you clean the wound, do a thorough visual inspection to gauge its seriousness and your comfort level in dealing with it. Call your veterinarian about any wound that concerns you or that

• is over a joint or could involve bone, tendons or ligaments
• has embedded hair, debris or dirt
• is estimated to be more than six hours old when it is discovered
• "gapes" when the horse moves, with its edges pulling apart
• is associated with any lameness or other obvious discomfort on the part of the horse.

Remember, says Hollis, some of the smallest wounds are the most dangerous: They are easily ignored and are sometimes very difficult to clean effectively. "The outside--visible--part of the wound may be small and 'insignificant,' but there may be contamination, tissue damage and even life-threatening infection present," she says. "It's far better to call for professional help immediately if you are even slightly worried."

Let the Healing Begin
Once the wound is clean, it's time to decide what to apply. "Your choice should be guided by what the body is doing at that point," says Hollis. During the initial phase of wound healing, the debridement stage, the body delivers white blood cells to the site to clean up damaged cells and foreign matter and defend against infection. These blood cells begin work within an hour of wounding, and for the next day or two the dead cells and bacteria are expelled from the wound as a clear or slightly yellowish discharge.

The sight of an oozing wound sends many people off-track. "There is a real instinct at this point to look at a wet, oozing wound and want to 'dry it up,'" says Hollis. "But that's the last thing you want to do. White blood cells are what trigger the 'cleanup' process and healing, and they need a moist environment to move in. If they do not have moisture to move around in, they get stuck and cannot work. So, if you 'dry up' a fresh wound, you hamper their work." Instead, she says, let it ooze, and even supplement its moisture with an ointment.