Your horse comes in from the pasture with a gash on his knee. No problem. Your first-aid kit is filled with wound-care options, including plain old iodine and a product that promises to prevent proud flesh. But which one should you use?

[READ: PREVENT HORSE WOUNDS]

Stop right there!

Even something as simple as plain old iodine can cause tissue damage that might compromise your horse’s healing. Your wound treatment could cause more harm than good.

Here I’ll go over the four stages of wound healing. I’ll first tell you what’s happening inside your horse’s body to help him heal. Then I’ll explain what you should (and shouldn’t) do when caring for a wound. (For a wound-care kit, turn to page 45.)

Stage 1 Hemostasis (Control of Bleeding)

When it occurs: Immediately after injury.

What’s happening inside: Blood vessels constrict to reduce blood flow. Within seconds, cells called platelets adhere to vessel walls. Within minutes, strands of fibrin (a stringy protein) adhere to damaged vessels where they begin to form a matrix or “mesh” to support clot development. Platelets release substances that stimulate clotting. Once a clot is formed, bleeding stops.

DO: Apply direct pressure.
If bleeding is excessive at this stage—especially if it “pumps,” indicating that a high-pressure artery may have been cut—it might overwhelm your horse’s body’s ability to form an effective clot. Apply direct pressure with a small pad of clean gauze under your fingers to help stop the bleeding. Hold for at least five minutes to ensure that it has stopped. If blood is still flowing freely, repeat. In severe cases, you might have to simply sit tight with direct pressure applied while waiting for your vet to arrive.

DO: Apply a bandage.
If bleeding is moderate—“puddling” not “pumping”—apply pressure using a bandage over a nonstick pad and thick layer of gauze. (To make this layer, take eight to 10 4-inch-by-4-inch gauze pads, and fold them in half.) This should control bleeding until your vet arrives.

DON’T: Apply cauterizing powder. Although it might be tempting, avoid applying any type of powder, spray, or other dressing designed to “cauterize” (“burn”) tissue to control blood flow. These products can severely damage tissues and lead to difficult healing down the road.

DON’T: Vigorously clean the wound.
It doesn’t take much to disrupt a fragile clot your horse’s body forms to help control bleeding. Avoid vigorously scrubbing or cleaning the wound when it’s very fresh—especially if it bled a lot.

DO: Take a picture.
After you’ve controlled the bleeding, take a photo of the wound both up close and far enough away to make it easy for your vet to see where the wound is located.

DO: Call your vet for advice.
After you’ve controlled the bleeding, call your vet while the wound is still very fresh. Follow your vet’s advice about what treatment he or she would recommend. If the wound needs suturing, it’ll always heal better if sutured than if left to heal on its own. Even if your vet has to make an emergency visit, you’ll save both time and money in the long run. Your photos will likely help him or her make decisions about whether a visit would
be recommended.

[READ: HORSE LUMPS & BUMPS GUIDE]

Stage 2 Inflammation

When it occurs: Within minutes of injury and lasts approximately three to five days.

What’s happening inside: After you’ve controlled the bleeding, vessels dilate to allow increased blood flow. Damaged vessels leak fluid into surrounding tissues. An influx of cells, enzymes, and nutrients helps prevent infection and allows healing to begin. This increase in blood flow is what causes the wound to become hot, swollen, and painful—the hallmark signs of inflammation. Inflammation is essential for healing, but if it’s excessive, it can delay the healing process.

DO: Rinse the wound.
As soon as you’ve controlled the bleeding, gently clean the wound with saline solution to help remove contamination. Contaminants can lead to an infection or otherwise hamper healing. Saline is ideal, because it has the same electrolyte balance as your horse’s body tissues. This helps maintain fluid balance and causes the least amount of damage. (To make your own saline solution, mix 1 teaspoon of salt into 1 quart of cold water.) If the wound is very dirty, or saline simply isn’t available, a gentle flushing with cold water is an acceptable alternative.

Cold water constricts blood vessels to minimize bleeding and help control inflammation. If the wound is associated with a significant amount of trauma, cold hosing might even be your vet’s first choice to help keep swelling to a minimum.

DON’T: Apply random ointments.
While it might be tempting to slather the wound with whatever ointment you find it your first-aid kit, don’t do it! Thick ointments can trap contaminants in the wound or hinder movement of cells that are necessary for cleaning up debris. Many ointments are also damaging to tissues—and the most important thing that you can do to encourage healing is to treat delicate tissues with utmost care.

DON’T: Clean the wound with strong antimicrobial agents.
Betadine, chlorhexidine, and hydrogen peroxide are all potentially damaging to tissues at this stage—and the stronger they are, the more damage they cause. Contrary to what you might think, flushing a wound with something like full-strength betadine is more likely to cause an infection than to help prevent one.

DO: Administer anti-inflammatory medications as directed.
Caveat: Take this step only on the advice of your vet. Your vet may opt to administer an anti-inflammatory medication—such as phenylbutazone or flunixin meglumine—at the time of suturing. Or, he or she will recommend that you administer these medications yourself to help minimize swelling and control excessive inflammation.

Stage 3 Proliferation (Repair)

When it occurs: This stage overlaps inflammation, beginning as early as eight to 10 hours after injury.

What’s happening inside: During this stage, your horse’s body begins a process called angiogenesis, in which damaged blood vessels are replaced within the wound area. Cells called fibroblasts develop. Fibroblasts act like bridges across the damaged tissues and eventually reorganize to form a kind of scaffolding that supports the healing process. Fibroblasts secrete a protein called collagen that helps hold everything together. During this stage of healing, you’ll see a bed of healthy (pink) granulation tissue. This tissue fills in the defect, provides a surface for epithelial (skin) cells to crawl across (called epithelialization), and eventually contracts (shrinks) as the wound becomes smaller over time. The process of epithelialization can be very slow, as cells migrate only 0.1 to 0.2 millimeters per day. The size of the gap will determine the length of time the repair stage lasts—and is one reason why a sutured wound (where skin edges are pulled together) heals so much faster than one that’s left to heal on its own.

DO: Keep the wound bandaged.
Keeping a wound bandaged helps prevent movement that can delay healing (especially important on the lower legs); controls excessive swelling; and helps maintain an ideal healing environment that’s clean, warm, and moist.

DO: Apply appropriate ointments.
For most uncomplicated wounds, a simple antimicrobial ointment, such as a triple antibiotic or silver sulfadiazine, is acceptable. These ointments have been shown to speed healing by keeping the wound moist and helping to prevent infection. In reality, a non-
antimicrobial ointment may be just as good, because the real advantage lies in keeping the wound moist, unless there are signs of infection, such as excessive heat, swelling, or pain. (Most vets agree it’s best to avoid nitrofurazone on a fresh wound; studies indicate this ointment can actually slow healing.) Finally, your vet might recommend a specific ointment at certain times during the healing process, such as one containing a corticosteroid to help control proud flesh (more on that in a minute). Only use these ointments as recommended by your vet, as they can slow the healing process.

DON’T: Leave a wound open to ‘dry out.’
Does your horse’s wound look “gooey” with a yellowish discharge? Good! This type of discharge is a normal part of the healing process, especially during the early days when white blood cells are busy doing clean-up duties. That’s right—it doesn’t mean the wound is infected, and it’s usually a good thing! The worst thing you can do is leave the wound “open” to allow it to dry out.
A moist wound is a happy wound. (As an interesting side note: Do you think the wound needs oxygen? A bandage actually lowers the pH of underlying tissues, which increases oxygenation. 

This means that when you leave the wound open, you’re actually compromising its oxygen supply.)

DO: Closely monitor the granulation bed.
Horses can be very enthusiastic healers, especially when lower-leg wounds are involved. The developing bed of granulation tissue must stay below the level of the surrounding skin margins to enable the skin cells to successfully “crawl across” them during epithelialization. If granulation tissue protrudes above the skin edges (proud flesh), healing can’t progress, because skin cells have to crawl “uphill.” If this occurs, call your vet. He or she may want to surgically trim back the tissue to allow healing to progress.

[READ: THE BEST WOUND HEALING TREATMENT]

Stage 4 Maturation (Remodeling)

When it occurs: After the wound appears completely healed.

What’s happening inside: During this process, the tissues become mature and reorganize to gain strength. Maturation can take months to years—it’s what makes that once-horrible scar harder and harder to see as time go by.

DON’T: Pull sutures too soon.
If your horse’s wound was sutured, it may look completely healed—until you pull out the sutures too soon, and the whole thing unzips. Remove sutures only when your vet gives you the green light. If you’re uncertain, consider removing every other suture initially, then remove the remaining sutures several days later.

DO: Wean carefully from a bandage.
If a lower-leg wound has been bandaged for a period of months, weeks, or even days, it’s likely to have reflex swelling when a supportive bandage is removed. Reflex swelling occurs when tissues that are used to being supported swell when the support is removed. Once the wound appears completely healed, carefully wean the wound from the bandage. Begin by removing the bandage for only two to three hours per day. Gradually increase the time you leave the bandage off over a period of several days. Before beginning the bandage-weaning process on a sutured lower-leg wound, ensure that the wound is holding together after you pull the sutures.

DO: Continue to protect the wounded area.
Even after healing is complete (which may take a year or more), wounded tissues may never be as strong as they once were. If the wound was in a vulnerable area, continue to protect it. For example, consider using performance boots or bandages during your horse’s workouts, and outfit your horse in shipping boots during travel to protect
a once-injured lower leg.

DO: Apply emollient dressings.
After your horse’s wound has healed, apply lanolin-based ointments to help restore moisture and elasticity to damaged skin. Apply ointment daily—or at least several times per week—until tissues appear moist and healthy.

Bottom line: When your horse gets a wound, the most important thing you can do is to optimize his own healing process by protecting his tissues and providing an optimal healing environment. 

[READ: YOUR BEST FIRST-AID KIT]