Scientiﬁc Communication The value of veterinary wound management for human wounds and wound care THE FIRST IN A SERIES: There remains much to learn about the science of wound healing in humans. It may be possible to improve our understanding of wound healing by looking to other disciplines. Veterinary wound healing research has something to offer and this article Wound healing and management is a challenge not only in human medicine but also in veterinary medicine. The struggles to heal complicated wounds in companion animal species are strikingly similar to those in human patients despite major differences between species. A comparison of the similarities in healing between species may identify new mammalian wound models with a much higher concordance rate, and a critical analysis of the differences may contribute to the common good. Sharing clinical problems, treatments, research, models, and ideas between human and veterinary experts can therefore beneﬁt both human and veterinary wound healing and management, which speaks for an intensiﬁed collaboration between human and veterinary wound healing associations. Animal wound models Although the majority of animal models in wound healing resear ch are based on rodents, the concordance rate between rodents and humans is only 53%, which suggests that results from rodent models are not likely to translate into improved clinical outcomes. A lack of concordance is not surprising given the anatomical, physiological, and immunological differences between rodents and humans1. For example; EWMA JOURNAL 2014 VOL 14 NO 2 adrid · Spain EWMA 䡲 GNEAUPP 2014 Submitted to the EWMA Journal, based on a presentation given a EWMA symposium (VWHA/EWMA Symposium on Veterinary Wound Management and Antimicrobial Resistance: Animal Wound Care - Best practice and new knowledge) at the EWMA · GNEAUPP 2014, Madrid. appears in the EWMA Journal as the ﬁrst in a series of articles that looks outside of the traditional topics covered. We hope that you enjoy learning about wound healing in another species and will gain a better understanding of the similarities that exist. the contribution of wound contraction and epithelialisation to second intention healing of cutaneous wounds varies signiﬁcantly across species due to differences in the gross and histologic structure of the skin. Rapid contraction is a common feature of loose skin, which is present in the body/trunk of most companion animals, including horses, dogs, and cats. In contrast, extremity wounds in these animals heal in a manner more similar to wounds in tight-skinned species (e.g., humans and porcines), primarily as the result of re-epithelialisation2. Limb wounds in horses and human leg wounds heal in a similar way: healing in both species occurs mainly through epithelialisation with only limited wound contraction (Table 1, Fig. 1). 䊳 Jacintha M. Wilmink DVM, PhD, Diplomate RNVA Veterinary Wound Healing Association (VWHA) Past President and Council Member Correspondence: [email protected] Conﬂicts of interest: None. Table 1: Comparative cutaneous wound healing across species. !") &) %$) "&) !) #&) !) 39 Scientiﬁc Communication Figure 1: An example of a horse limb wound that has healed almost completely by epithelialisation. Figure 2: An example of a horse limb wound with unhealthy granulation tissue, necrotic parts, and bioﬁlm formation, which most likely is subject to chronic inﬂammation. Some excess granulation tissue has already formed. EQUINE WOUNDS AS A MODEL FOR HUMAN WOUNDS AND WOUND CARE: DIFFERENCES AND SIMILARITIES Differences between human and equine patients and wounds At ﬁrst glance, human and equine patients do not seem to have much in common, and their wounds seem very different. Human patients are often elderly and sometimes obese or with nutritional deﬁciencies. Many human patients suffer from systemic diseases that lead to vascular, diabetic, or pressure ulcers. These ulcers occur gradually with the progression of the disease, must heal by second intention, and often develop into chronic, difﬁcult to heal wounds. In contrast, equine patients are usually less than 3 years of age and in normal nutritional condition. Their wounds are the result of sudden trauma, and the aim of treatment is primary intention healing. Not all wounds can be sutured, however, and wound dehiscence occurs frequently, which means that many wounds must heal by second intention and can develop into chronic, difﬁcult to heal wounds. Similarities between human and equine wounds Although human and equine patients and wounds are 40 Figure 3: Fibroproliferative disorders in the horse. This horse exhibits EGT in the central part of the wound, hypertrophic scarring along the wound margins, congestion, edema, and ﬁbrosis in the tissues around the wound and distal limb. initially very different, both species can suffer strikingly similar problems with second intention healing. It is close to normal for the limb wounds of horses to form unhealthy granulation tissue that is covered in bioﬁlm and subject to chronic inﬂammation (Fig. 2). In contrast to human wounds, that often have a lack of granulation tissue, exuberant granulation tissue (EGT) is a regular complication in horse wounds (Fig. 3). The clinical presentation of EGT is similar to that of human keloids, except that equine EGT is not epithelialised. Horse limb wounds sometimes develop scars that look like keloids, but histology shows that these are hypertrophic scars rather than true keloids. Horses, but not ponies, have a genetic predisposition for developing EGT and hypertrophic scars. Likewise, a genetic susceptibility to keloid formation has been observed in humans. Similarities in the histological appearance and dysregulated cytokine proﬁles of these ﬁbroproliferative disorders in horses and humans have been shown3. Another similarity between humans and equines is the hypoxia of wounds. In horses, wound hypoxia is caused by the anatomy of the limbs, which have only 2 main arteries running to the distal limb and limited collateral alternatives. When a horse limb is injured, the perfusion of the wound and the distal part of the limb can be dam- EWMA JOURNAL 2014 VOL 14 NO 2 aged, both by vessels that are cut and/or obstructed by clots or by the swelling of the tissues as a reaction to the traumatic incident. Equine wounds can therefore suffer from impaired oxygenation as well as problems with the venous return, which can lead to congestion, oedema, and ﬁnally to ﬁbrosis (Fig. 3). The ﬁnal similarity between human and equine wounds is the susceptibility of limb wounds to the development of pressure sores. Equine pressure sores occur due to treatment with bandages or casts. The causes are the same as those that are known in humans: the amount of pressure, the duration of time in which the pressure is present, and shearing forces. A similar division in the severity and depth of pressure sores or ulcers can be made in equine and humans. Comparative physiology It has been shown that within the equine species horses heal much slower and with more complications than ponies. By comparing many aspects of the physiology of wound healing between these sub-species, it has been determined that most of the differences in clinical healing can be explained by the course of the inﬂammatory response and the capacity of leucocytes to produce inﬂammatory mediators. This knowledge has resulted in enormous improvement in clinical treatment strategies. THE EWMA EWMA 2015 UNIVERSITY LONDON · UK CONFERENCE MODEL (UCM) 13 -15 MAY 2015 in London The EWMA UCM programme offers students of wound management from institutes of higher education across Europe the opportunity to take part of their academic studies whilst participating in the EWMA Conference. The opportunity of participating in the EWMA UCM is available to all teaching institutions with wound management courses for health professionals. The UCM programme at the EWMA 2015 Conference in London will offer networking opportunities between the students from various UCM groups, UCM Lectures as well as assignments and workshops arranged speciﬁcally for the UCM students. EWMA strongly encourages teaching institutions and students from all countries to beneﬁt from the possibilities of international networking and access to lectures by many of the most experienced wound management experts in the world. Yours sincerely Comparing the (patho)physiology of human and equine wounds may also reveal new elements of wound healing and wound management. The similarities in the epithelialisation/contraction ratio, the development of ﬁbroproliferative disorders, bioﬁlm formation, chronic inﬂammation, dysregulated cytokine proﬁles, hypoxia, and problems with pressure may introduce some promising modeling alternatives to consider. In addition, naturally occurring horse wounds may be useful for clinical trials because neither equine nor human wounds can be easily mimicked in experimental set-ups. The correlation between human and equine wounds may lead to the development of new insights and treatments for both species. We conclude that further collaborations between human and veterinary experts in wound healing and management 䡵 will be of beneﬁt to both ﬁelds. Dubravko Huljev Chair of the Education Committee Participating institutions: Donau Universität Krems Austria Haute École de Santé Geneva, Switzerland HUB Brussels Belgium Lithuanian University of Health Sciences Lithuania University of Hertfordshire United Kingdom Universidade Católica Portuguesa Porto, Portugal References 1. Special Section Wound Repair and Regeneration: Wound healing in Veterinary Medicine; Asking the right questions to ﬁnd the keys to wound healing. WRR 2013;21:363. 2. Volk SW and Bohling MW. Comparative wound healing- Are the small animal veterinarian’s clinical patients an improved translational model for human wound healing research? WRR. 2013;21:372-81 3. Theoret CL and Wilmink JM. Aberrant wound healing in the horse: naturally occurring conditions reminiscent of those observed in man. WRR. 2013;21:365-71. For further information about the EWMA UCM, please visit the Education section of the EWMA website www.ewma.org or contact the EWMA Secretariat at [email protected] EWMA JOURNAL 2014 VOL 14 NO 2 41 INNOVATIVE SOLUTIONS VeraFlo Therapy ™ NO ONE IMAGINED WOUND THERAPY COULD GET ANY BETTER… WE DID V.A.C.Ulta™ Negative Pressure Wound Therapy System: more granulation In a porcine study comparing V.A.C.® Therapy to VeraFlo™ Therapy with saline, there was 43%* more granulation after 7 days of therapy. TWO THERAPIES, ONE SYSTEM. VeraFlo™ Therapy can help Cleanse, Treat and Heal by combining the beneﬁts of V.A.C.® Therapy with automated solution distribution, dwell and removal. Cellulose acetate mesh, coated with soft tack silicone ® ADAPTIC TOUCH NON-ADHERING SILICONE DRESSING ALL YOU COULD WISH FOR IN A WOUND CONTACT LAYER It is also suitable for use, under medical supervision, with NEGATIVE PRESSURE WOUND THERAPY (NPWT). 4326/ACE/GLO/0914/PRB3613 x20 magniﬁcation www.kci-medical.com www.systagenix.com * Results have not yet been conﬁrmed in humans. Lessing MC, et al. Negative Pressure Wound Therapy With Controlled Saline Instillation (NPWTi): Dressing Properties and Granulation Response In Vivo. Wounds 2011; 23:309-319. NOTE: Speciﬁc indications, contraindications, warnings, precautions and safety information exist for KCI and Systagenix products and therapies. Please consult a physician and product instructions for use prior to application. This material is intended for healthcare professionals. © 2014 KCI Licensing, Inc. All rights reserved. All trademarks designated herein are proprietary to KCI Licensing, Inc., its afﬁliates and/or licensors. DSL#14-0456.SYX4326.EWMA (9/14)