QUARTERLY BEAT / OCTOBER 2025
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 species. 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
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.
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 bush. 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.
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
A tarsal wound with infection and exuberant granulation tissue (Photo courtesy of Dr. Holly Roessner, DACVS-LA)
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
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