January 2026
In this VETgirl online veterinary continuing education blog, Dr. Holly Roessner, DACVS-LA, details topical therapy options for those challenging wounds horses seem prone to experiencing. Read below to review the phases of wound healing and what topical treatment therapies are available!

Topical Therapies for Wound Healing in Horses

Dr. Holly Roessner, DACVS-LA, North Carolina State University

Wounds are a common part of equine practice. If possible, primary closure is preferred to result in a better functional and cosmetic outcome. Successful primary closure results in shorter healing time and decreased costs. Unfortunately, primary closure may not always be possible, especially if there is significant tissue loss or infection present. Alternatively, primary closure can fail due to excessive tension, motion, or underlying infection, resulting in the need for second intention wound healing. Many topical therapies exist to aid in this process, with three main goals in mind: maintaining a moist environment, reducing the antimicrobial load, and enhancing the wound environment to support the phases of wound healing.

Wound healing is comprised of four phases:

  1. Hemostasis
  2. Inflammation
  3. Proliferation
  4. Maturation or remodeling

These phases overlap and total timing depends on multiple factors, including wound size, presence of infection, and immune status of the patient.

Wound infection is common in equine patients due to a high likelihood of contamination at the time of injury. Additional risk factors for infection include the presence of foreign material or sequestrum formation, poor vascular supply to wounds on the distal limbs, and the immune status of the patient. Horses with uncontrolled pituitary pars intermedia dysfunction (PPID) have reduced tissue healing and increased likelihood for infection.

Clinical signs of wound infection include excessive discharge, poor quality granulation tissue, signs of local infection, and a failure to respond to therapy. Systemic antimicrobials are generally utilized in addition to topical therapies. Wound debridement is critical and may need to be performed multiple times, as biofilm is often present and can reform within 24-72 hours. Tissue culture and sensitivity is recommended to guide therapy in any chronic, non-healing wounds.

A. A shoulder wound with primary closure failure and infection. B. Cleaned, debrided, and treated with manuka honey. Photos courtesy of Dr. Holly Roessner, DACVS-LA.

There is an abundance of topical medications available for use, with limited scientific evidence and regulatory oversight.

Topicals with antimicrobial activity:

  • Triple antibiotic ointment (neomycin, polymyxin B, and bacitracin) is a classic topical antibiotic. It has a wide antimicrobial spectrum but is ineffective against Pseudomonas The zinc portion of bacitracin stimulates epithelialization but can retard wound contraction. In a controlled experimental study, wounds treated with triple antibiotic ointment healed 13 days slower compared to non-treated wounds, making it a less favorable choice for equine wounds.1
  • Silver sulfadiazine 1% ointment is a commonly used topical, with a wide antimicrobial spectrum, including Pseudomonas and fungi. It is an excellent topical choice for wounds, including all types of burns. SSD binds to tissue to form inactive silver compounds, so it must be applied at least once daily for maximum antimicrobial efficacy. The cream does not adhere well to the wound bed, so a bandage is often utilized to hold it in place.
  • Medical grade manuka honey is made by bees pollinating the Leptospermum scoparium Manuka honey has a wide antimicrobial spectrum due to the presence of unique manuka factor (UMF), a compound known as methylglyoxal. A higher UMF is associated with superior healing. Manuka honey reduces inflammation by reducing edema and the presence of debris and necrotic tissue within the wound bed. Manuka honey promotes a moist environment, and wounds usually appear more exudative compared to wounds treated with other topical medications. Multiple studies support the use of medical grade manuka honey for wound healing, including a study in which treated wounds healed 12 days faster compared to untreated wounds.2 There has been speculation that nonmedical grade honey made locally would have improved antimicrobial activity against resident bacteria. Unfortunately, nonmedical grade honey has a significant risk of bacterial or fungal contamination with unknown efficacy. Therefore, medical grade honey with a high UMF should be used if possible. This product is available in gel, paste, and prefabricated calcium alginate sheets that can be cut to size.
  • Cadexomer iodine is a 0.9% iodine in starch gel. Iodine is slowly released from the starch molecules, leading to enhanced antimicrobial activity. It is effective against MRSA and Pseudomonas biofilms in mice wounds and ex vivo in equine wounds, but no in vivo equine studies exist.3
  • Amorphous silicate gel (Zarasyl) is a patented barrier cream comprised of amorphous silicate nanoparticles and polyethylene glycol. There are no controlled studies, but a retrospective series in horses reported no exuberant granulation tissue, no complications, and high owner satisfaction.4
  • Octenidine dihydrochloride is a hydrogel with wide antimicrobial spectrum, including fungi and Pseudomonas. In humans, octenidine hydrogel has shown improved healing of chronic wounds. There are no studies in horses.
  • While nitrofurazone has a wide antimicrobial spectrum, it is inactivated by wound exudate and is ineffective against Pseudomonas. Most importantly, nitrofurazone is a reported carcinogen, causing ovarian and mammary tumors in mice and rats. Additionally, nitrofurazone decreases epithelialization and contraction and promotes exuberant granulation tissue. While still used by some today, there are many superior, safer products available.

Exuberant granulation tissue is common in distal limb wounds of horses due to a prolonged inflammatory phase, combined with microvascular occlusion of capillaries and an imbalance of collagen homeostasis. While bandages are frequently utilized to maintain a clean wound healing environment particularly in the distal limb, they can stimulate angiogenesis and formation of inflammatory exudate, contributing to a prolonged inflammatory phase.

A tarsal wound with infection and exuberant granulation tissue. Photo courtesy of Dr. Holly Roessner, DACVS-LA.

The primary treatment for exuberant granulation tissue is debridement. The presence of granulation tissue above the skin edges halts epithelialization and contraction, so the granulation bed should be trimmed to just below the skin edge. Topical steroids can be used judiciously to reduce the formation.

Topical Steroids:

  • Triamcinolone or triamcinolone containing antifungal and antibiotic creams are often used to reduce formation of exuberant granulation tissue, but other steroids can be used as well. Topical steroids are contraindicated in infected wounds, and substantially delay wound healing by delaying contraction, epithelialization, and angiogenesis. Use should be limited to 1-3 applications maximum.

Biologic Topicals:

  • Platelet rich plasma (PRP) gel has become a popular treatment for wounds, particularly if a practitioner already has access to a commercially available PRP kit and centrifuge. The gel is then easily made using a PRP kit, which activates platelets using thrombin and calcium gluconate to form a gel. Platelets provide growth factors and hydrolytic enzymes that are useful in multiple phases of healing. PRP has been shown to improve angiogenesis, shorten the inflammatory phase, and improve epithelialization and collagen organization in multiple equine studies.5 While this is promising, the price point is considerably higher compared to other topicals mentioned here and needs to be considered.
  • Amnion, the innermost layer of fetal membranes, has increased in popularity over the last few years as a wound healing treatment. Amnion has been shown to contain valuable growth factors, modulate inflammation, recruit stem cells, and promote epithelialization. It is available commercially as a sheet or injectable liquid. If a practitioner has access to fresh, healthy amnion, it is relatively simple to harvest, inexpensive to process, can be cut to size, and can be stored up to 12 months for future use.6 Multiple equine studies showed favorable results, with amnion-treated wounds displaying reduced granulation tissue and more rapid healing time.7

A. A metacarpal wound treated with amnion. B. Healing well 7 weeks later. Photos courtesy of Dr. Holly Roessner, DACVS-LA.

In summary, there are many topical products available. Some should never be used (nitrofurazone), some should be used with caution in certain scenarios only (steroids), and others can be used based on practitioner experience and preference. The topicals presented here have some, though still limited, evidence-based support. Frequent evaluation of wound healing to ensure it is progressing as expected is recommended. Repeat debridement should be performed if infection or exuberant granulation tissue occurs, and underlying metabolic disorders affecting the immune system should be diagnosed and treated if wound healing is still delayed.

References:

  1. Bischofberger AS, Tsang AS, Horadagoda N, et al. Effect of activated protein C in second intention healing of equine distal limb wounds: a preliminary study. Aust Vet J. 2015;93:361–6.
  2. Bischofberger AS, Dart CM, Perkins NR, et al. The effect of short- and long-term treatment with manuka honey on second intention healing of contaminated and noncontaminated wounds on the distal aspect of the forelimbs in horses. Vet Surg. 2013;42:154–60.
  3. De Clercq E, Den Hondt S, De Baere C, et al. Effects of various wound dressings on microbial growth in perfused equine musculocutaneous flaps. Am J Vet Res. 2021;82:189–197.
  4. Chevalier JM, Pearson GB. Amorphous silicate technology produces good results in equine distal limb wound healing. J Am Vet Med Assoc. 2023;261(6):1-5.
  5. Monteiro SO, Lepage OM, Theoret CL. Effects of platelet-rich plasma on the repair of wounds on the distal aspect of the forelimb in horses. Am J Vet Res. 2009;70(2):277-82.
  6. McCoy AM. How to prepare ad store equine amnion for use as a biological wound dressing. AAEP Proceedings 2017. https://www.cabidigitallibrary.org/doi/pdf/10.5555/20193333603
  7. Fowler AW, Gilbertie JM, Watson VE, et al. Effects of acellular equine amniotic allografts on the healing of experimentally induced full thickness distal limb wounds in horses. Vet Surg. 2019; 48: 1416-1428.

 

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