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A Novel Bioelectric Device Enhances Wound Healing: An Equine Case Series
Journal of Equine Veterinary Science 34 (2014) 421–430
Contents lists available at ScienceDirect
Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Case Report
A Novel Bioelectric Device Enhances Wound Healing: An Equine Case Series Janet D. Varhus DVM * Animal Care Center, Poncha Springs, CO, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 March 2013 Received in revised form 22 May 2013 Accepted 23 July 2013 Available online 7 November 2013
The use of low-level microcurrents for accelerated wound healing is well documented. A case series was conducted to assess wound healing outcomes following the application of a wireless, current-generating bioelectric wound care device in 10 equines that presented with traumatic injuries in the lower extremity. Wounds were treated with a bioelectric device held in place with standard bandaging twice a week. At each follow-up visit, wounds were photographed and assessed for signs of epithelialization. All presented wounds were reduced in size or achieved complete wound closure, with an average 1.3% wound healing per day. The results of this case series demonstrate the safety and efficacy of a bioelectric device as a management option for traumatic lower-extremity wounds in equines and hold significant promise in promoting enhanced healing rates and improved aesthetic outcomes. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Equine Wound healing Bioelectric wound device Traumatic wounds
1. Introduction Lower-limb injuries in the equine population are common occurrences but pose a significant challenge to the caretaker because of poor blood supply and increased tension and movement in the horse’s extremities. Implications are far reaching and tragic, with slower healing rates and increased chance of complications from infection, placing the horse at greater risk for euthanasia. Proper wound management and bandaging are vital in preventing contamination and promoting the wound healing process, especially in wounds located over areas with high motion and proximal to critical structures. The current standard of equine wound care entails cleansing the wound, surgery to debride exuberant granulation tissue that often accompanies this type of injury, pressure bandages, and various topical agents. Casts are often applied to stabilize the area
* Corresponding author at: Janet D. Varhus, DVM, Animal Care Center, PO Box 578, Poncha Springs, CO 81242. E-mail address: [email protected]. 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2013.07.011
and are left on for 1 to 2 months, followed by bandages for 1 to 4 months. A wide variety of topical agents are available on the market for the management of wounds. Traditional standard-of-care treatments, ranging from powders to antimicrobials, have often been observed to result in slow healing and unsatisfactory cosmetic outcomes. More advanced wound care options, ranging from use of chitin and collagen to extracellular matrix and platelet-rich plasma [1-4], are efficacious but often cost more and are resource-intensive. Research findings from recent decades point to the benefits of low-level microcurrents in directing cell migration in wound healing [5,6]. Electric stimulation has long been used in the treatment of wounds as a healing modality, with application of direct microcurrents to wounds, resulting in a reduction in pain, inflammation, and time to healing [7-9]. Endogenous electrical activity is naturally present in mammalian skin. Electrical activity in the form of microcurrents is present at the wound site, specifically constrained to the wound perimeter wherein the tissue layer ends are exposed to conductive fluids. With skin injury, physiologic electrical
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potential helps cells migrate throughout the wound site. This electrical signal is essential to the cascade of reactions and processes required to initiate and sustain wound healing, especially cell transport to the injury site [10-12]. Cells are transported along electrical current lines, which are generated in wounds via a process called electrotaxis or galvanotaxis. Keratinocytes, neutrophils, mast cells, and microbes migrate in the presence of low-level microcurrents from the wound perimeter into the wound site near the wound edge [12-14]. Microcurrents applied to wounds have been shown to augment wound healing [15-17]. The roles of both zinc and silver have been widely accepted as beneficial in facilitating wound healing [18,19]. Both zinc and silver are used in antimicrobial formulations and act as important cofactors for wound healing as well as for modulating the markers required for efficacious wound healing. Furthermore, many research studies demonstrate that antimicrobial activity is enhanced by synergistic activity of a bioelectric environment and the element of silver [7,20,21]. A novel, antimicrobial wound device (Procellera bioelectric wound device; Vomaris, Chandler, AZ, USA) has been used for acute, chronic, partial, and full-thickness wounds in humans and animals [22-24]. This device contains elemental silver and zinc, which are applied on the device surface in a dot matrix pattern, creating multiple microbatteries. The device is self-contained and wireless and can be cut to fit a specific wound. No external power supply is required. It is bioelectric by inherent design; in the presence of a conductive fluid, which may come from wound exudate or exogenous fluids, including normal saline, a sustained voltage in the range of 0.3 to 0.9 volts is
generated on the surface of the wireless device. When the device is activated, the presence of adjacent cells of silver and zinc produces a sustained, predetermined depth of current similar to the voltage that occurs at areas of skin injury in normal hosts. Recent findings from human and animal studies point to accelerated wound healing rates and enhanced healing outcomes with the use of the bioelectric device [22-24]. In vivo porcine studies [22,23] demonstrated with statistical significance that compared to controls, in the presence of the bioelectric device partial and full-thickness wounds epithelialized faster (up to 3 times at Day 5) and downregulated interleukin-1a at Day 8, and, over the 8day postwound initiation, the collagen markers COL-1 and COL-3 evolved to indicate a better long-term repair in terms of remodeling and wound strength. Findings from a prospective study of human skin graft donor site wounds showed 34.6% faster wound healing (P ¼ .015) in bioelectric device-treated wounds at 1 week than in controls, with overall improved scar quality (P ¼ .03) [24] at 1 month. The following case series illustrates improved outcomes with the bioelectric device in the management of 10 lower-extremity equine wounds. The device was moistened with a conductive fluid, applied to the cleansed wound site, and secured in place with self-adherent wrap and waterproof tape, with dressing changes every 3 to 4 days. Wounds were observed closely for signs of healing initiation and epithelialization. Wound dimensions, including length and width, were measured and recorded at each dressing change, and digital photographs were taken of the wound. An autoregressive analysis (which allows for correlated measures over time) with a lag 1
Fig. 1. (A) 5 days post-injury; wound area 135.3 cm2. (B) Day 18; wound area 142.8 cm2 Pain greatly decreased. Now able to tolerate full weight bearing. No longer on pain medication or antibiotics. (C) Day 26; wound area 38.8 cm2. Granulation tissue becoming healthier, with evidence of hoof regrowth. (D) Day 62; wound area 24.3 cm2. Granulation tissue red and healthy. Lateral avulsed hoof wall removed exposing new hoof growth. New hair growth present. (E) Day 74; wound area 19.4 cm2. Euthanasia prevented.
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covariance structure was used to model intra-horse variation over time and to provide an aggregate estimate of healing rate expressed as average percent wound healing per day. The lag 1 covariance structure means that measures closer to one another in time will be more highly correlated than measures that are more distant from one another. Using this structure to model the correlation of measures within one subject over time is intended to avoid violating the assumption of correlated errors, which, if violated, biases the estimate of the standard error (variability) of the measurements, and hence the confidence intervals and P-values. SPSS version 21 software (SPSS Inc, Chicago, Ill.) was used for analysis. 2. Case Report 2.1. Case Report 1: Laceration Treated with Bioelectric Wound Device 2.1.1. Presentation A 10-year-old Quarter Horse gelding presented with a full-thickness injury to the skin, coronary band, and medial heel bulb (Fig. 1). The wound extended from just
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distal to the fetlock on the midline around the medial aspect of the pastern to the caudal heel. Exposure of the coffin bone was present where the hoof wall was avulsed from the lamina. Origin of the injury was unknown. 2.1.2. Management The wound was initially treated with traditional bandages (Telfa pad, Covidien, Mansfield, MA, USA; brown gauze; Gamgee cotton padding roll, Vetrap, 3M, St. Paul, MN, USA; ) and nitrofurazone (Furacin; Neogen, Lexington, KY, USA). Five days after the initial injury, the horse presented with a large amount of granulation tissue, and the bandage was soaked in mucopurulent exudate. At Day 6 postinjury, following wound cleansing, an amorphous hydrogel (Carravet Acemannan wound gel; Carrington Laboratories, Irving, TX, USA) was applied to the wound and covered with the bioelectric device held in place with a gauze roll (Kerlix bandage roll, Covidien), cotton (Gamgee cotton padding roll; 3M), and self-adherent wrap (Vetrap; 3M). Casting material was applied to the hoof to stabilize the avulsed hoof wall to protect the coffin bone and other structures. The device was changed every 4 to 5 days. The patient was started on phenylbutazone (SuperiorBute
Fig. 2. (A) Post-injury day 24, prior to placement of bioelectric dressing. (B) Day 6 application of bioelectric dressing, improved quality of granulation tissue. (C) Day 12; significant stimulation of epithelium. (D) Day 17; 81.1% decrease in wound area. (E) Day 28; wound closed. (F) Day 52; significant decrease in size of scar and regrowth of hair. (G) Day 81; complete hair regrowth and little evidence of wound.
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powder; Superior Equine Pharmaceuticals, Inc, Pleasant Grove, UT), 2 grams daily for 1 week and reduced to 1 gram daily for another week when it was discontinued.
duration (Fig. 2). Origin of the injury was unknown. The former show horse had most recently competed in thirdlevel dressage, jumping.
2.1.3. Outcome At Day 18 from the initial injury, the wound was reepithelialized, with exuberant tissue granulation resolved, without need for debridement or casting of the wound. No antibiotics were given, and the wound did not show signs of infection. The patient was fully weight-bearing and required no pain medication. By Day 26, the wound had contracted to half the original size, and evidence of hoof regrowth was present. At 62 days postinjury, the lateral avulsed hoof wall was removed, exposing new hoof growth underneath. The pastern wound continued to contract with new hair regrowth and minimal scarring. At 74 days from starting treatment, the patient was sent home with minimal bandaging and hoof care, with euthanasia prevented.
2.2.2. Management Previous treatments included nitrofurazone with wound powder (Wonder Dust; Farnam, Phoenix, AZ) and a mild dilution of peroxide solution spray. The bioelectric device was applied 3 weeks postinjury and moistened with hydrogel and covered with a saline-moistened gauze, selfadherent wrap, semiocclusive film (Tegaderm; 3M), and an additional layer of self-adherent wrap and secured in place with waterproof tape (Perma-Type Pink Tape; Permatype, Plainville, CT, USA). Dressings were changed at 3- to 4-day intervals.
2.2. Case Report 2: Traumatic Abrasion Treated with a Bioelectric Wound Device 2.2.1. Presentation A 13-year-old Appaloosa gelding presented with a fullthickness wound to the left dorsal pastern of 24 days’
2.2.3. Outcome A 41.1% reduction in wound area was noted after 6 days of treatment with the bioelectric device, with epithelial tissue evident and granulation tissue observed to be red and healthy. A 63.3% decrease in wound area was noted at Day 12, with significant epithelialization at 24 days. Continued decrease in scar tissue and regrowth of normal skin and hair were observed at Day 24, with improved wound contraction.
Fig. 3. (A) Initial wound at medial aspect of the right hind gaskin (upper site); wound area 13.8 cm2. (B) Initial wound at medial aspect of the right hind gaskin (lower site); wound area 1.7 cm2. (C) Day 3, first dressing change after application of bioelectric dressing; upper site wound area 0.7 cm2, with lower site closed. (D) Day 19; complete hair regrowth in upper and lower wound sites.
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Fig. 4. (A) Post- injury day 20; prior to placement of bioelectric dressing. (B) Day 7; exuberant granulation tissue resolving. (C) Day 14; reduction of wound area with improved granulation tissue. (D) Day 35; 67.2% reduction in wound area with significant wound contraction. (E) Day 42; vibrant granulation tissue and wound contraction with minimal scarring. (F) Day 55; 97% reduction in wound area.
2.3. Case Reports 3 and 4: Traumatic Abrasion Treated with a Bioelectric Wound Device 2.3.1. Presentation Two additional abrasions were observed on the medial aspect of the right gaskin of the horse presented in section 2.2. Case report 2 (Fig. 3).
2.3.2. Management The bioelectric device was applied upon discovery of the injury and secured in the same fashion. The device was left in place for 3 days, and the wound was left open to air and covered with a zinc-based ointment (Secura Extra protective cream; Smith & Nephew, London, UK).
Fig. 5. (A) Post-injury day 20; wound prior to placement of bioelectric dressing. (B) Day 4; 15.2% decrease in wound area in spite of only being exposed to the bioelectric dressing for 24 hours. (C) Day 7; 41.1% decrease in wound area in one week. Exuberant granulation less prominent and is healthy and vibrant in color. (D) Day 14; 74.4% decrease in wound area with significant contraction and regrowth of hair. (E) Day 21; bioelectric dressing treatment concluded at the request of owner.
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Fig. 6. (A) 20 days post-injury; prior to placement of bioelectric dressing. (B) Day 7; beefy red granulation tissue present with rapid epithelialization. (C) Day 14; 58% reduction in wound area with healthy edges and hair regrowth. (D) Day 21; conclusion of treatment at owners request. (E) Day 56; significant hair regrowth.
2.3.3. Outcome Epithelialization of the wounds was observed at Day 3, with complete regrowth of hair noted at day 19.
right and left pasterns following a collision with a metal fence (Figs. 4-7).
2.4. Case Reports 5-8: Traumatic Wounds Treated with a Bioelectric Wound Device
2.4.2. Management Previous treatment included wound spray (Vetericyn; Innovacyn, Rialto, CA) applied daily and phenylbutazone for pain control. The bioelectric wound device was applied 20 days postinjury, covered with a saline-moistened gauze, and self-adherent wrap and secured in place with
2.4.1. Presentation An 11-year-old Appaloosa mare trail horse presented with 4 full-thickness wounds to the palmar aspect of the
Fig. 7. (A) 20 days post-injury; prior to placement of bioelectric dressing. (B) Day 7; 72.6% decrease in wound area with significant epithelium and initiation of hair regrowth. (C) Day 14; 86.3% decrease in wound area, with wound contraction and hair regrowth evident. (D) Day 21; bioelectric dressing treatment concluded at the request of owner. (E) Day 56; continued hair regrowth.
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waterproof tape. Dressings were changed at 3- to 4-day intervals. 2.4.3. Outcome Following initial application of the bioelectric device, all wounds progressed well without complication, and pain medication ceased. Case 5 was significantly reduced by 93.3% at Day 56; case 6 achieved a 74.4% reduction at Day 14; and cases 7 and 8 achieved significant epithelialization and hair regrowth at 3 weeks. 2.5. Case Report 5: Traumatic Laceration Treated with a Bioelectric Wound Device
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was reapplied at Day 4 (Fig. 5). The wound was observed to have a 15.2% decrease in area at Day 4. At the seventh-day dressing change, a 41.1% decrease in wound area was noted, with increased perfusion and flattening of hypergranulation tissue. A 74.4% decrease in wound area was noted at Day 14, and the bioelectric device was discontinued at Day 21 at the request of the owner prior to full closure. 2.7. Case Report 7: Traumatic Abrasion Treated with a Bioelectric Wound Device
Case 5, located on the lateral pastern, decreased 93.3% over the course of 56 days (Fig. 4). Physical examination showed improved perfusion with exuberant granulation tissue resolved.
Case 7, located on the cranial aspect of the right hock, demonstrated significant improvement 4 days after initial application of the bioelectric device, with a 39.3% decrease in wound area (Fig. 6). Early examination showed edema, possibly caused by slippage of the dressing complex. At 1 week, significant improvement in perfusion was observed, followed by epithelialization at 3 weeks.
2.6. Case Report 6: Traumatic Abrasion Treated with a Bioelectric Wound Device
2.8. Case Report 8: Traumatic Abrasion Treated with a Bioelectric Wound Device
The device for case 6, located at the caudal aspect of the cannon bone, slipped postapplication after 24 hours and
Case 8, located on the caudal aspect of the right rear pastern, showed a 72.6% decrease in wound area at the
Fig. 8. (A) Post-injury day 28; prior to placement of bioelectric dressing. (B) Day 3; Significant epithelialization noted at inferior portion of the wound. (C) Day 8; 37.2% decrease in wound area. (D) Day 20; epithelium maturing with hair regrowth. Granulation tissue flattened and healthy. (E) Day 31; 87.1% decrease in wound area. (F) Day 38; granulation tissue vibrant and beefy red. Wound contraction with thick hair growth present. (G) Treatment concluded at owner’s request.
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seventh-day dressing change, with significant improvement and hair regrowth in surrounding scar tissue (Fig. 7). At 2 weeks postapplication of the bioelectric device, the wound had decreased by 86.3% in area, with substantial epithelialization at Day 21.
2.9. Case Report 9: Traumatic Laceration Treated with a Bioelectric Wound Device 2.9.1. Presentation A 10-year-old American Saddlebred dressage and show mare presented with a full-thickness traumatic laceration to the dorsal aspect of the right hind leg following kicking through a fence (Fig. 8). 2.9.2. Management Previous treatment included nitrofurazone, cold hosing, self-adherent wrap, wound powder, and phenylbutazone. The bioelectric device was applied 28 days postinjury and was covered with a saline-moistened gauze, self-adherent wrap, semiocclusive film, and an additional layer of self-adherent wrap and secured in place with elastic adhesive tape (Elastikon; Johnson & Johnson, New Brunswick, NJ, USA). Dressings were changed at 3- to 4-day intervals. 2.9.3. Outcome Phenylbutazone therapy was ceased after initiation of the bioelectric device. At Day 6 postapplication of the bioelectric device, examination of the wound showed a 37.2% decrease in wound area, with significant reepithelialization. New hair growth noted at the inferior portion of the wound at Day 20 assessment, with
significant epithelialization of the wound at Day 43. The bioelectric device was discontinued at this time. 2.10. Case Report 10: Traumatic Laceration Treated with a Bioelectric Wound Device 2.10.1. Presentation A 16-year-old quarter horse gelding used for dressage, eventing, and lessons presented with a laceration to the lateral aspect of the right hind pastern following collision with the stall (Fig. 9). 2.10.2. Management The bioelectric device was applied immediately postinjury and covered with a saline-moistened gauze, semiocclusive film, and self-adherent wrap and secured in place with elastic adhesive tape immediately postinjury. Dressings were changed at 3- to 4-day intervals. 2.10.3. Outcome A 93.8% resolution of the original wound was observed at Day 4 postapplication of the bioelectric device, with a minute residual opening in the center of the wound. A small detached skin flap was removed at evaluation. Improved, healthy pigmentation was observed in the scar tissue, and regrowth of hair was noted at the seventh-day assessment. Substantial ingrowth of hair was observed at 18 days, with improved scar appearance at 25 days. 3. Results and Discussion All wounds in the presented case studies treated with the bioelectric device demonstrated positive healing
Fig. 9. (A) Day 0 post- injury. (B) Day 1 post-application of bioelectric dressing. (C) Day 8; 90.7% decrease in wound area. (D) Day 15; stabilized with two small wounds and hair re-growth at the peri-wound margins. (E) Day 25; upper wound smaller with significant contraction and epithelium present and lower wound closed. Total hair re-growth at the peri-wound areas. Treatment terminated at the request of the owner.
J.D. Varhus / Journal of Equine Veterinary Science 34 (2014) 421–430 Table 1 Average percent wound healing per day Case
No. of Days of Treatment
Initial Wound Area (cm2)
Ending Wound Area (cm2)
Percent Reduction in Wound Area/Day
BD BD BD BD BD BD BD BD BD BD
68 24 3 3 56 14 14 14 38 26
135.5 9 13.8 1.68 40.25 15.75 7 8.75 77 16.5
19.3 0 0.7 0 1.17 3.8 2.94 1.2 9.24 0.5
1.2 4.1 31.6 33.3 1.8 5.6 3.7 5.2 2.3 3.7
1 2 3 4 5 6 7 8 9 10
BD, bioelectric wound device.
improvement, with no apparent patient discomfort or adverse effects observed. Of the 10 wounds presented in the case series, 6 of the wounds were at least 3 weeks old; only 1 of the 10 wounds was treated with the bioelectric device immediately after injury. In two of the cases, owners chose to discontinue use of the dressing after most of the wound had closed, prior to completion of reepithelialization, so the horse could return to training and activity. It is worthwhile to note, of the three patients that required analgesics prior to initiation of bioelectric therapy, two no longer required any analgesics after starting therapy (cases 5-9), and use of analgesics had decreased (case 1). As electrical stimulation has been widely used as a modality for the management of pain [25,26], the apparent abatement of pain in the aforementioned cases may have been attributed to the analgesic effect of low-level microcurrent stimulation from the bioelectric device. Variable healing rates were observed in the cases treated with the bioelectric device, ranging from 1.2% wound healing per day (case 1) to 33.3% wound healing per day (case 4) (Table 1). The average percent wound healing per day, according to the autoregressive model for all 10 wounds treated with the bioelectric device was 1.3% (95% confidence interval: 0.8%-1.9%) (Fig. 10). The variability of the healing rates may have been attributed to the range in depths of the wounds, compliance of the patient, sufficient
Fig. 10. 1.3 Average percent wound healing per day based on auto-regressive model for bioelectric wound device treated wounds
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moisture levels under the secondary dressings used to keep the bioelectric device activated, and sufficiently secured secondary dressings. While encouraging findings of enhanced re-epithelialization, decreased inflammation, reduced pain reduced eschar formation, hair regrowth, and favorable cosmetic outcome were observed in the 10 presented cases, there are a number of limitations to this case series. A relatively small population of cases were prospectively observed (n ¼ 10) in a nonrandomized, observational nature, with variable interim wound healing measurements. Lower extremity wounds have been known to be life threatening and crippling to horses. Factors including increased risk of bacterial contamination and infections, decreased blood supply, reduced soft tissue support, and wounds over areas of high motion all contribute to prolonged healing, unsatisfactory cosmetic outcomes, and poor functional outcomes. In 8 of the 10 cases that achieved complete wound closure in the present case series, mean healing time was 30 days. Average healing times for lowerleg wounds treated with standard dressings, as well as advanced wound care approaches, typically range from several weeks to months [27-31]. In an analysis of 33 equines in four wound healing studies of the distal limb, Dart et al [27] observed greater and more prolonged wound retraction and presence of excessive granulation tissue following standard bandaging than with unbandaged controls. No differences in healing rates (cm2/day) or healing times were observed in the studies between the two groups (P ¼ .43), with a mean total of 75 days to healing of bandaged wounds versus 66 days for unbandaged wounds [27]. Bello [28], in a case series of 10 equines with traumatic wounds and lacerations of the lower extremities and bodies, determined a mean 86.3 % reduction in wound healing at 3 months of treatment, based upon initial measurements. Wounds were treated with a combination of standard cleansing agents, ointments, collagen dressings, standard bandages, and a cyanoacrylate spray. In a randomized controlled trial of six healthy adult horses with surgically created wounds of the lower limb, Morgan et al [29] observed a mean healing time of 76 days following treatment with extracorporeal shock wave therapy compared to 90 days in untreated wounds. Taking into consideration standard wound healing rates and below-satisfactory healing outcomes with traditional wound management techniques, modalities that enhance the wound healing environment and expedite the rate and quality of healing play an invaluable role in reducing risk for loss of function and euthanasia and in restoring the horse to performance. Also of significant importance to the horse owner are wound care approaches that reduce the horse’s pain and facilitate improved aesthetic outcomes through minimized scar appearance and foster hair regrowth. Positive findings of the use of the bioelectric device in this case series warrants further exploration in subsequent randomized and controlled studies as well as in wound models in other species. Based on its results, it appears that the application of an antimicrobial, closeproximity electrically active wound device may be considered safe and effective in facilitating the healing of
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acute and chronic equine wounds. Additionally, the bioelectric wound device may serve as a viable wound management approach in improving overall healing outcomes and possibly provide a new option for the standard of equine wound care. Acknowledgments I thank Eryn Wolfwalker and Penny Campbell, PT, CWS, for technical advising and Prof. Curt Bay, PhD, AT Still University, for providing expertise and assistance in the descriptive analysis of the data. References [1] Alford CG, Caldwell FJ, Hanson RH. Equine distal limb wounds: new and emerging treatments. Compend Contin Educ Vet 2012;34: E1–6. [2] Caston SS. Wound care in horses. Vet Clin North Am Equine Pract 2012;28:83–100. [3] Madison JB, Hamir AN, Ehrlich HP, et al. Effects of a proprietary topical medication on wound healing and collagen deposition in horses. Am J Vet Res 1991;52:1128–31. [4] Berry II DB, Sullins KE. Effects of topical application of antimicrobials and bandaging on healing and granulation tissue formation in wounds of the distal aspect of the limbs in horses. Am J Vet Res 2003;64:88–92. [5] Nishimura KY, Isseroff RR, Nuccitelli R. Human keratinocytes migrate to the negative pole in direct current electric fields comparable to those measured in mammalian wounds. J Cell Sci 1996;109:199–207. [6] Zhao M. Electrical fields in wound healingdan overriding signal that directs cell migration. Semin Cell Dev Biol 2009;20:674–82. [7] Huckfeldt R, Flick AB, Mikkelson D, Lowe C, Finley PJ. Wound closure after split-thickness skin grafting is accelerated with the use of continuous direct anodal micro current applied to silver nylon wound contact dressings. J Burn Care Res 2007;28:703–7. [8] Carley PJ, Wainapel SF. Electrotherapy for acceleration of wound healing: low intensity direct current. Arch Phys Med Rehabil 1985; 66:443–6. [9] Kloth LC, Feedar J. Acceleration of wound healing with high voltage, monophasic pulsed electrical current. Phys Ther 1988;68:503–8. [10] Foulds IS, Barker AT. Human skin battery potentials and their possible role in wound healing. Brit J Dermatol 1983;109:515–22. [11] Sheridan DM, Isseroff RR, Nucitelli R. Imposition of a physiologic DC electric current alters the migratory response of human keratinocytes on extracellular matrix molecules. J Invest Dermatol 1996; 106:642–6. [12] Vanable Jr JW. Integumentary potentials and wound healing. In: Borgens RB, Robinson KR, Vanable Jr JW, McGinnis ME, editors. Electric fields in vertebrate repair. New York: Alan R. Liss; 1989. p. 171–224. [13] Nishimura KYIR, Nuccitelli R. Human keratinocytes migrate to the negative pole in direct current electric fields comparable to those measured in mammalian wounds. J Cell Sci 1996;109:199–207.
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Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Case Report
A Novel Bioelectric Device Enhances Wound Healing: An Equine Case Series Janet D. Varhus DVM * Animal Care Center, Poncha Springs, CO, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 5 March 2013 Received in revised form 22 May 2013 Accepted 23 July 2013 Available online 7 November 2013
The use of low-level microcurrents for accelerated wound healing is well documented. A case series was conducted to assess wound healing outcomes following the application of a wireless, current-generating bioelectric wound care device in 10 equines that presented with traumatic injuries in the lower extremity. Wounds were treated with a bioelectric device held in place with standard bandaging twice a week. At each follow-up visit, wounds were photographed and assessed for signs of epithelialization. All presented wounds were reduced in size or achieved complete wound closure, with an average 1.3% wound healing per day. The results of this case series demonstrate the safety and efficacy of a bioelectric device as a management option for traumatic lower-extremity wounds in equines and hold significant promise in promoting enhanced healing rates and improved aesthetic outcomes. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Equine Wound healing Bioelectric wound device Traumatic wounds
1. Introduction Lower-limb injuries in the equine population are common occurrences but pose a significant challenge to the caretaker because of poor blood supply and increased tension and movement in the horse’s extremities. Implications are far reaching and tragic, with slower healing rates and increased chance of complications from infection, placing the horse at greater risk for euthanasia. Proper wound management and bandaging are vital in preventing contamination and promoting the wound healing process, especially in wounds located over areas with high motion and proximal to critical structures. The current standard of equine wound care entails cleansing the wound, surgery to debride exuberant granulation tissue that often accompanies this type of injury, pressure bandages, and various topical agents. Casts are often applied to stabilize the area
* Corresponding author at: Janet D. Varhus, DVM, Animal Care Center, PO Box 578, Poncha Springs, CO 81242. E-mail address: [email protected]. 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2013.07.011
and are left on for 1 to 2 months, followed by bandages for 1 to 4 months. A wide variety of topical agents are available on the market for the management of wounds. Traditional standard-of-care treatments, ranging from powders to antimicrobials, have often been observed to result in slow healing and unsatisfactory cosmetic outcomes. More advanced wound care options, ranging from use of chitin and collagen to extracellular matrix and platelet-rich plasma [1-4], are efficacious but often cost more and are resource-intensive. Research findings from recent decades point to the benefits of low-level microcurrents in directing cell migration in wound healing [5,6]. Electric stimulation has long been used in the treatment of wounds as a healing modality, with application of direct microcurrents to wounds, resulting in a reduction in pain, inflammation, and time to healing [7-9]. Endogenous electrical activity is naturally present in mammalian skin. Electrical activity in the form of microcurrents is present at the wound site, specifically constrained to the wound perimeter wherein the tissue layer ends are exposed to conductive fluids. With skin injury, physiologic electrical
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potential helps cells migrate throughout the wound site. This electrical signal is essential to the cascade of reactions and processes required to initiate and sustain wound healing, especially cell transport to the injury site [10-12]. Cells are transported along electrical current lines, which are generated in wounds via a process called electrotaxis or galvanotaxis. Keratinocytes, neutrophils, mast cells, and microbes migrate in the presence of low-level microcurrents from the wound perimeter into the wound site near the wound edge [12-14]. Microcurrents applied to wounds have been shown to augment wound healing [15-17]. The roles of both zinc and silver have been widely accepted as beneficial in facilitating wound healing [18,19]. Both zinc and silver are used in antimicrobial formulations and act as important cofactors for wound healing as well as for modulating the markers required for efficacious wound healing. Furthermore, many research studies demonstrate that antimicrobial activity is enhanced by synergistic activity of a bioelectric environment and the element of silver [7,20,21]. A novel, antimicrobial wound device (Procellera bioelectric wound device; Vomaris, Chandler, AZ, USA) has been used for acute, chronic, partial, and full-thickness wounds in humans and animals [22-24]. This device contains elemental silver and zinc, which are applied on the device surface in a dot matrix pattern, creating multiple microbatteries. The device is self-contained and wireless and can be cut to fit a specific wound. No external power supply is required. It is bioelectric by inherent design; in the presence of a conductive fluid, which may come from wound exudate or exogenous fluids, including normal saline, a sustained voltage in the range of 0.3 to 0.9 volts is
generated on the surface of the wireless device. When the device is activated, the presence of adjacent cells of silver and zinc produces a sustained, predetermined depth of current similar to the voltage that occurs at areas of skin injury in normal hosts. Recent findings from human and animal studies point to accelerated wound healing rates and enhanced healing outcomes with the use of the bioelectric device [22-24]. In vivo porcine studies [22,23] demonstrated with statistical significance that compared to controls, in the presence of the bioelectric device partial and full-thickness wounds epithelialized faster (up to 3 times at Day 5) and downregulated interleukin-1a at Day 8, and, over the 8day postwound initiation, the collagen markers COL-1 and COL-3 evolved to indicate a better long-term repair in terms of remodeling and wound strength. Findings from a prospective study of human skin graft donor site wounds showed 34.6% faster wound healing (P ¼ .015) in bioelectric device-treated wounds at 1 week than in controls, with overall improved scar quality (P ¼ .03) [24] at 1 month. The following case series illustrates improved outcomes with the bioelectric device in the management of 10 lower-extremity equine wounds. The device was moistened with a conductive fluid, applied to the cleansed wound site, and secured in place with self-adherent wrap and waterproof tape, with dressing changes every 3 to 4 days. Wounds were observed closely for signs of healing initiation and epithelialization. Wound dimensions, including length and width, were measured and recorded at each dressing change, and digital photographs were taken of the wound. An autoregressive analysis (which allows for correlated measures over time) with a lag 1
Fig. 1. (A) 5 days post-injury; wound area 135.3 cm2. (B) Day 18; wound area 142.8 cm2 Pain greatly decreased. Now able to tolerate full weight bearing. No longer on pain medication or antibiotics. (C) Day 26; wound area 38.8 cm2. Granulation tissue becoming healthier, with evidence of hoof regrowth. (D) Day 62; wound area 24.3 cm2. Granulation tissue red and healthy. Lateral avulsed hoof wall removed exposing new hoof growth. New hair growth present. (E) Day 74; wound area 19.4 cm2. Euthanasia prevented.
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covariance structure was used to model intra-horse variation over time and to provide an aggregate estimate of healing rate expressed as average percent wound healing per day. The lag 1 covariance structure means that measures closer to one another in time will be more highly correlated than measures that are more distant from one another. Using this structure to model the correlation of measures within one subject over time is intended to avoid violating the assumption of correlated errors, which, if violated, biases the estimate of the standard error (variability) of the measurements, and hence the confidence intervals and P-values. SPSS version 21 software (SPSS Inc, Chicago, Ill.) was used for analysis. 2. Case Report 2.1. Case Report 1: Laceration Treated with Bioelectric Wound Device 2.1.1. Presentation A 10-year-old Quarter Horse gelding presented with a full-thickness injury to the skin, coronary band, and medial heel bulb (Fig. 1). The wound extended from just
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distal to the fetlock on the midline around the medial aspect of the pastern to the caudal heel. Exposure of the coffin bone was present where the hoof wall was avulsed from the lamina. Origin of the injury was unknown. 2.1.2. Management The wound was initially treated with traditional bandages (Telfa pad, Covidien, Mansfield, MA, USA; brown gauze; Gamgee cotton padding roll, Vetrap, 3M, St. Paul, MN, USA; ) and nitrofurazone (Furacin; Neogen, Lexington, KY, USA). Five days after the initial injury, the horse presented with a large amount of granulation tissue, and the bandage was soaked in mucopurulent exudate. At Day 6 postinjury, following wound cleansing, an amorphous hydrogel (Carravet Acemannan wound gel; Carrington Laboratories, Irving, TX, USA) was applied to the wound and covered with the bioelectric device held in place with a gauze roll (Kerlix bandage roll, Covidien), cotton (Gamgee cotton padding roll; 3M), and self-adherent wrap (Vetrap; 3M). Casting material was applied to the hoof to stabilize the avulsed hoof wall to protect the coffin bone and other structures. The device was changed every 4 to 5 days. The patient was started on phenylbutazone (SuperiorBute
Fig. 2. (A) Post-injury day 24, prior to placement of bioelectric dressing. (B) Day 6 application of bioelectric dressing, improved quality of granulation tissue. (C) Day 12; significant stimulation of epithelium. (D) Day 17; 81.1% decrease in wound area. (E) Day 28; wound closed. (F) Day 52; significant decrease in size of scar and regrowth of hair. (G) Day 81; complete hair regrowth and little evidence of wound.
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powder; Superior Equine Pharmaceuticals, Inc, Pleasant Grove, UT), 2 grams daily for 1 week and reduced to 1 gram daily for another week when it was discontinued.
duration (Fig. 2). Origin of the injury was unknown. The former show horse had most recently competed in thirdlevel dressage, jumping.
2.1.3. Outcome At Day 18 from the initial injury, the wound was reepithelialized, with exuberant tissue granulation resolved, without need for debridement or casting of the wound. No antibiotics were given, and the wound did not show signs of infection. The patient was fully weight-bearing and required no pain medication. By Day 26, the wound had contracted to half the original size, and evidence of hoof regrowth was present. At 62 days postinjury, the lateral avulsed hoof wall was removed, exposing new hoof growth underneath. The pastern wound continued to contract with new hair regrowth and minimal scarring. At 74 days from starting treatment, the patient was sent home with minimal bandaging and hoof care, with euthanasia prevented.
2.2.2. Management Previous treatments included nitrofurazone with wound powder (Wonder Dust; Farnam, Phoenix, AZ) and a mild dilution of peroxide solution spray. The bioelectric device was applied 3 weeks postinjury and moistened with hydrogel and covered with a saline-moistened gauze, selfadherent wrap, semiocclusive film (Tegaderm; 3M), and an additional layer of self-adherent wrap and secured in place with waterproof tape (Perma-Type Pink Tape; Permatype, Plainville, CT, USA). Dressings were changed at 3- to 4-day intervals.
2.2. Case Report 2: Traumatic Abrasion Treated with a Bioelectric Wound Device 2.2.1. Presentation A 13-year-old Appaloosa gelding presented with a fullthickness wound to the left dorsal pastern of 24 days’
2.2.3. Outcome A 41.1% reduction in wound area was noted after 6 days of treatment with the bioelectric device, with epithelial tissue evident and granulation tissue observed to be red and healthy. A 63.3% decrease in wound area was noted at Day 12, with significant epithelialization at 24 days. Continued decrease in scar tissue and regrowth of normal skin and hair were observed at Day 24, with improved wound contraction.
Fig. 3. (A) Initial wound at medial aspect of the right hind gaskin (upper site); wound area 13.8 cm2. (B) Initial wound at medial aspect of the right hind gaskin (lower site); wound area 1.7 cm2. (C) Day 3, first dressing change after application of bioelectric dressing; upper site wound area 0.7 cm2, with lower site closed. (D) Day 19; complete hair regrowth in upper and lower wound sites.
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Fig. 4. (A) Post- injury day 20; prior to placement of bioelectric dressing. (B) Day 7; exuberant granulation tissue resolving. (C) Day 14; reduction of wound area with improved granulation tissue. (D) Day 35; 67.2% reduction in wound area with significant wound contraction. (E) Day 42; vibrant granulation tissue and wound contraction with minimal scarring. (F) Day 55; 97% reduction in wound area.
2.3. Case Reports 3 and 4: Traumatic Abrasion Treated with a Bioelectric Wound Device 2.3.1. Presentation Two additional abrasions were observed on the medial aspect of the right gaskin of the horse presented in section 2.2. Case report 2 (Fig. 3).
2.3.2. Management The bioelectric device was applied upon discovery of the injury and secured in the same fashion. The device was left in place for 3 days, and the wound was left open to air and covered with a zinc-based ointment (Secura Extra protective cream; Smith & Nephew, London, UK).
Fig. 5. (A) Post-injury day 20; wound prior to placement of bioelectric dressing. (B) Day 4; 15.2% decrease in wound area in spite of only being exposed to the bioelectric dressing for 24 hours. (C) Day 7; 41.1% decrease in wound area in one week. Exuberant granulation less prominent and is healthy and vibrant in color. (D) Day 14; 74.4% decrease in wound area with significant contraction and regrowth of hair. (E) Day 21; bioelectric dressing treatment concluded at the request of owner.
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Fig. 6. (A) 20 days post-injury; prior to placement of bioelectric dressing. (B) Day 7; beefy red granulation tissue present with rapid epithelialization. (C) Day 14; 58% reduction in wound area with healthy edges and hair regrowth. (D) Day 21; conclusion of treatment at owners request. (E) Day 56; significant hair regrowth.
2.3.3. Outcome Epithelialization of the wounds was observed at Day 3, with complete regrowth of hair noted at day 19.
right and left pasterns following a collision with a metal fence (Figs. 4-7).
2.4. Case Reports 5-8: Traumatic Wounds Treated with a Bioelectric Wound Device
2.4.2. Management Previous treatment included wound spray (Vetericyn; Innovacyn, Rialto, CA) applied daily and phenylbutazone for pain control. The bioelectric wound device was applied 20 days postinjury, covered with a saline-moistened gauze, and self-adherent wrap and secured in place with
2.4.1. Presentation An 11-year-old Appaloosa mare trail horse presented with 4 full-thickness wounds to the palmar aspect of the
Fig. 7. (A) 20 days post-injury; prior to placement of bioelectric dressing. (B) Day 7; 72.6% decrease in wound area with significant epithelium and initiation of hair regrowth. (C) Day 14; 86.3% decrease in wound area, with wound contraction and hair regrowth evident. (D) Day 21; bioelectric dressing treatment concluded at the request of owner. (E) Day 56; continued hair regrowth.
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waterproof tape. Dressings were changed at 3- to 4-day intervals. 2.4.3. Outcome Following initial application of the bioelectric device, all wounds progressed well without complication, and pain medication ceased. Case 5 was significantly reduced by 93.3% at Day 56; case 6 achieved a 74.4% reduction at Day 14; and cases 7 and 8 achieved significant epithelialization and hair regrowth at 3 weeks. 2.5. Case Report 5: Traumatic Laceration Treated with a Bioelectric Wound Device
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was reapplied at Day 4 (Fig. 5). The wound was observed to have a 15.2% decrease in area at Day 4. At the seventh-day dressing change, a 41.1% decrease in wound area was noted, with increased perfusion and flattening of hypergranulation tissue. A 74.4% decrease in wound area was noted at Day 14, and the bioelectric device was discontinued at Day 21 at the request of the owner prior to full closure. 2.7. Case Report 7: Traumatic Abrasion Treated with a Bioelectric Wound Device
Case 5, located on the lateral pastern, decreased 93.3% over the course of 56 days (Fig. 4). Physical examination showed improved perfusion with exuberant granulation tissue resolved.
Case 7, located on the cranial aspect of the right hock, demonstrated significant improvement 4 days after initial application of the bioelectric device, with a 39.3% decrease in wound area (Fig. 6). Early examination showed edema, possibly caused by slippage of the dressing complex. At 1 week, significant improvement in perfusion was observed, followed by epithelialization at 3 weeks.
2.6. Case Report 6: Traumatic Abrasion Treated with a Bioelectric Wound Device
2.8. Case Report 8: Traumatic Abrasion Treated with a Bioelectric Wound Device
The device for case 6, located at the caudal aspect of the cannon bone, slipped postapplication after 24 hours and
Case 8, located on the caudal aspect of the right rear pastern, showed a 72.6% decrease in wound area at the
Fig. 8. (A) Post-injury day 28; prior to placement of bioelectric dressing. (B) Day 3; Significant epithelialization noted at inferior portion of the wound. (C) Day 8; 37.2% decrease in wound area. (D) Day 20; epithelium maturing with hair regrowth. Granulation tissue flattened and healthy. (E) Day 31; 87.1% decrease in wound area. (F) Day 38; granulation tissue vibrant and beefy red. Wound contraction with thick hair growth present. (G) Treatment concluded at owner’s request.
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seventh-day dressing change, with significant improvement and hair regrowth in surrounding scar tissue (Fig. 7). At 2 weeks postapplication of the bioelectric device, the wound had decreased by 86.3% in area, with substantial epithelialization at Day 21.
2.9. Case Report 9: Traumatic Laceration Treated with a Bioelectric Wound Device 2.9.1. Presentation A 10-year-old American Saddlebred dressage and show mare presented with a full-thickness traumatic laceration to the dorsal aspect of the right hind leg following kicking through a fence (Fig. 8). 2.9.2. Management Previous treatment included nitrofurazone, cold hosing, self-adherent wrap, wound powder, and phenylbutazone. The bioelectric device was applied 28 days postinjury and was covered with a saline-moistened gauze, self-adherent wrap, semiocclusive film, and an additional layer of self-adherent wrap and secured in place with elastic adhesive tape (Elastikon; Johnson & Johnson, New Brunswick, NJ, USA). Dressings were changed at 3- to 4-day intervals. 2.9.3. Outcome Phenylbutazone therapy was ceased after initiation of the bioelectric device. At Day 6 postapplication of the bioelectric device, examination of the wound showed a 37.2% decrease in wound area, with significant reepithelialization. New hair growth noted at the inferior portion of the wound at Day 20 assessment, with
significant epithelialization of the wound at Day 43. The bioelectric device was discontinued at this time. 2.10. Case Report 10: Traumatic Laceration Treated with a Bioelectric Wound Device 2.10.1. Presentation A 16-year-old quarter horse gelding used for dressage, eventing, and lessons presented with a laceration to the lateral aspect of the right hind pastern following collision with the stall (Fig. 9). 2.10.2. Management The bioelectric device was applied immediately postinjury and covered with a saline-moistened gauze, semiocclusive film, and self-adherent wrap and secured in place with elastic adhesive tape immediately postinjury. Dressings were changed at 3- to 4-day intervals. 2.10.3. Outcome A 93.8% resolution of the original wound was observed at Day 4 postapplication of the bioelectric device, with a minute residual opening in the center of the wound. A small detached skin flap was removed at evaluation. Improved, healthy pigmentation was observed in the scar tissue, and regrowth of hair was noted at the seventh-day assessment. Substantial ingrowth of hair was observed at 18 days, with improved scar appearance at 25 days. 3. Results and Discussion All wounds in the presented case studies treated with the bioelectric device demonstrated positive healing
Fig. 9. (A) Day 0 post- injury. (B) Day 1 post-application of bioelectric dressing. (C) Day 8; 90.7% decrease in wound area. (D) Day 15; stabilized with two small wounds and hair re-growth at the peri-wound margins. (E) Day 25; upper wound smaller with significant contraction and epithelium present and lower wound closed. Total hair re-growth at the peri-wound areas. Treatment terminated at the request of the owner.
J.D. Varhus / Journal of Equine Veterinary Science 34 (2014) 421–430 Table 1 Average percent wound healing per day Case
No. of Days of Treatment
Initial Wound Area (cm2)
Ending Wound Area (cm2)
Percent Reduction in Wound Area/Day
BD BD BD BD BD BD BD BD BD BD
68 24 3 3 56 14 14 14 38 26
135.5 9 13.8 1.68 40.25 15.75 7 8.75 77 16.5
19.3 0 0.7 0 1.17 3.8 2.94 1.2 9.24 0.5
1.2 4.1 31.6 33.3 1.8 5.6 3.7 5.2 2.3 3.7
1 2 3 4 5 6 7 8 9 10
BD, bioelectric wound device.
improvement, with no apparent patient discomfort or adverse effects observed. Of the 10 wounds presented in the case series, 6 of the wounds were at least 3 weeks old; only 1 of the 10 wounds was treated with the bioelectric device immediately after injury. In two of the cases, owners chose to discontinue use of the dressing after most of the wound had closed, prior to completion of reepithelialization, so the horse could return to training and activity. It is worthwhile to note, of the three patients that required analgesics prior to initiation of bioelectric therapy, two no longer required any analgesics after starting therapy (cases 5-9), and use of analgesics had decreased (case 1). As electrical stimulation has been widely used as a modality for the management of pain [25,26], the apparent abatement of pain in the aforementioned cases may have been attributed to the analgesic effect of low-level microcurrent stimulation from the bioelectric device. Variable healing rates were observed in the cases treated with the bioelectric device, ranging from 1.2% wound healing per day (case 1) to 33.3% wound healing per day (case 4) (Table 1). The average percent wound healing per day, according to the autoregressive model for all 10 wounds treated with the bioelectric device was 1.3% (95% confidence interval: 0.8%-1.9%) (Fig. 10). The variability of the healing rates may have been attributed to the range in depths of the wounds, compliance of the patient, sufficient
Fig. 10. 1.3 Average percent wound healing per day based on auto-regressive model for bioelectric wound device treated wounds
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moisture levels under the secondary dressings used to keep the bioelectric device activated, and sufficiently secured secondary dressings. While encouraging findings of enhanced re-epithelialization, decreased inflammation, reduced pain reduced eschar formation, hair regrowth, and favorable cosmetic outcome were observed in the 10 presented cases, there are a number of limitations to this case series. A relatively small population of cases were prospectively observed (n ¼ 10) in a nonrandomized, observational nature, with variable interim wound healing measurements. Lower extremity wounds have been known to be life threatening and crippling to horses. Factors including increased risk of bacterial contamination and infections, decreased blood supply, reduced soft tissue support, and wounds over areas of high motion all contribute to prolonged healing, unsatisfactory cosmetic outcomes, and poor functional outcomes. In 8 of the 10 cases that achieved complete wound closure in the present case series, mean healing time was 30 days. Average healing times for lowerleg wounds treated with standard dressings, as well as advanced wound care approaches, typically range from several weeks to months [27-31]. In an analysis of 33 equines in four wound healing studies of the distal limb, Dart et al [27] observed greater and more prolonged wound retraction and presence of excessive granulation tissue following standard bandaging than with unbandaged controls. No differences in healing rates (cm2/day) or healing times were observed in the studies between the two groups (P ¼ .43), with a mean total of 75 days to healing of bandaged wounds versus 66 days for unbandaged wounds [27]. Bello [28], in a case series of 10 equines with traumatic wounds and lacerations of the lower extremities and bodies, determined a mean 86.3 % reduction in wound healing at 3 months of treatment, based upon initial measurements. Wounds were treated with a combination of standard cleansing agents, ointments, collagen dressings, standard bandages, and a cyanoacrylate spray. In a randomized controlled trial of six healthy adult horses with surgically created wounds of the lower limb, Morgan et al [29] observed a mean healing time of 76 days following treatment with extracorporeal shock wave therapy compared to 90 days in untreated wounds. Taking into consideration standard wound healing rates and below-satisfactory healing outcomes with traditional wound management techniques, modalities that enhance the wound healing environment and expedite the rate and quality of healing play an invaluable role in reducing risk for loss of function and euthanasia and in restoring the horse to performance. Also of significant importance to the horse owner are wound care approaches that reduce the horse’s pain and facilitate improved aesthetic outcomes through minimized scar appearance and foster hair regrowth. Positive findings of the use of the bioelectric device in this case series warrants further exploration in subsequent randomized and controlled studies as well as in wound models in other species. Based on its results, it appears that the application of an antimicrobial, closeproximity electrically active wound device may be considered safe and effective in facilitating the healing of
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acute and chronic equine wounds. Additionally, the bioelectric wound device may serve as a viable wound management approach in improving overall healing outcomes and possibly provide a new option for the standard of equine wound care. Acknowledgments I thank Eryn Wolfwalker and Penny Campbell, PT, CWS, for technical advising and Prof. Curt Bay, PhD, AT Still University, for providing expertise and assistance in the descriptive analysis of the data. References [1] Alford CG, Caldwell FJ, Hanson RH. Equine distal limb wounds: new and emerging treatments. Compend Contin Educ Vet 2012;34: E1–6. [2] Caston SS. Wound care in horses. Vet Clin North Am Equine Pract 2012;28:83–100. [3] Madison JB, Hamir AN, Ehrlich HP, et al. Effects of a proprietary topical medication on wound healing and collagen deposition in horses. Am J Vet Res 1991;52:1128–31. [4] Berry II DB, Sullins KE. Effects of topical application of antimicrobials and bandaging on healing and granulation tissue formation in wounds of the distal aspect of the limbs in horses. Am J Vet Res 2003;64:88–92. [5] Nishimura KY, Isseroff RR, Nuccitelli R. Human keratinocytes migrate to the negative pole in direct current electric fields comparable to those measured in mammalian wounds. J Cell Sci 1996;109:199–207. [6] Zhao M. Electrical fields in wound healingdan overriding signal that directs cell migration. Semin Cell Dev Biol 2009;20:674–82. [7] Huckfeldt R, Flick AB, Mikkelson D, Lowe C, Finley PJ. Wound closure after split-thickness skin grafting is accelerated with the use of continuous direct anodal micro current applied to silver nylon wound contact dressings. J Burn Care Res 2007;28:703–7. [8] Carley PJ, Wainapel SF. Electrotherapy for acceleration of wound healing: low intensity direct current. Arch Phys Med Rehabil 1985; 66:443–6. [9] Kloth LC, Feedar J. Acceleration of wound healing with high voltage, monophasic pulsed electrical current. Phys Ther 1988;68:503–8. [10] Foulds IS, Barker AT. Human skin battery potentials and their possible role in wound healing. Brit J Dermatol 1983;109:515–22. [11] Sheridan DM, Isseroff RR, Nucitelli R. Imposition of a physiologic DC electric current alters the migratory response of human keratinocytes on extracellular matrix molecules. J Invest Dermatol 1996; 106:642–6. [12] Vanable Jr JW. Integumentary potentials and wound healing. In: Borgens RB, Robinson KR, Vanable Jr JW, McGinnis ME, editors. Electric fields in vertebrate repair. New York: Alan R. Liss; 1989. p. 171–224. [13] Nishimura KYIR, Nuccitelli R. Human keratinocytes migrate to the negative pole in direct current electric fields comparable to those measured in mammalian wounds. J Cell Sci 1996;109:199–207.
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