Healing time of experimentally induced distal limb wounds in horses is not reduced by local injection of equine-origin liquid amnion allograft

Abstract

OBJECTIVE To assess the efficacy of an equine-origin liquid amnion allograft (ELAA) derived from both amniotic fluid and amniotic membrane on the healing time of experimentally induced distal limb wounds in horses. ANIMALS 8 adult horses. PROCEDURES On day 0, horses were anesthetized and a 2.5 X 2.5-cm, full-thickness skin wound was created on the dorsal aspect of each metacarpus and bandaged. On day 9, wound margins were injected with ELAA (treatment) or 0.9% NaCl (control). Bandages were changed at specific intervals through day 91 and, on each occasion, wounds were photographed to allow calculation of wound area. Exuberant granulation tissue was resected, if present. Wounds were deemed healed when completely epithelialized. Mean wound area was compared between groups throughout the study period. RESULTS Only 1 wound (control) remained unhealed at day 91. No difference was found between the treatment and control groups in either wound area over time (P = 1.0) or time for wounds to reduce in size by 95% (P = .2) Exuberant granulation tissue required resection twice (1 control wound and 1 treatment wound). CLINICAL RELEVANCE In this model, a single treatment with ELAA administered locally by SC injection did not accelerate distal limb wound healing in horses. However, it is possible that naturally occurring, chronic, or nonhealing wounds would respond differently.

Review of skin grafting in equine wounds: Indications and techniques

“…Allografts involve using skin from another horse, which carries a higher risk of host site rejection. Recently, the efficacy of an injectable allogeneic amnion product has been of interest with regard to wound healing, although one study indicated that there is no significant difference in experimental wound model healing compared to controls (Duddy et al., 2022). Finally, use of xenografts, such as porcine or fish skin, that do not integrate into the recipient animal wound bed but are instead used as biological bandages have been described.…”

“…Allografts involve using skin from another horse, which carries a higher risk of host site rejection. Recently, the efficacy of an injectable allogeneic amnion product has been of interest with regard to wound healing, although one study indicated that there is no significant difference in experimental wound model healing compared to controls (Duddy et al, 2022).…”

The effects of a synthetic epidermis spray on secondary intention wound healing in adult horses

“…In a retrospective study including 500 injured horses and ponies, only 26% of the wounds in horses were successfully treated with primary closure [7]. Horses often live in highly contaminated environments and secondary intention wound healing is usually predominant [8][9][10]. However, wounds on the limbs can lead to complications and additional treatment is often required [2,11].…”

Antinociceptive and wound healing effects of a commercial formulation of lidocaine, bupivacaine, adrenaline and cetrimide applied topically to superficial skin wounds in horses

“…There is considerable interest in developing novel approaches to improve the healing rate of lower limb wounds in horses, 1 with, histori-cally, a strong focus on optimising the wound bed microclimate. 2 The effect of treatment has been investigated in experimental models of surgically created wounds 2,3 and in clinical trials of naturally occurring wounds 4 ; however, such studies have focused heavily on wound healing without considering analgesia.…”