Autologous, split skin transplantation on the lower limbs of horses.

The skin grafting experiments were carried out on the cannon regions of horses to throw light on four matters relating to split skin transplantation. They were: The thickness of donor split skin that would provide good wound cover and still leave adequate tissue to permit uneventful healing at the donor site; whether split skin grafts were more readily accepted on fresh than on granulating wounds; the size of wounds that would benefit from grafting; and the maximum size of graft that would be readily accepted. The findings were: Split skin grafts 0.76 mm thickness gave the best results although grafts 0.63 mm thickness were satisfactory; split skin grafts were accepted more readily on fresh wounds than on granulating tissue; wounds which exceeded 1/10th of the skin area on the cannon region justified grafting; the upper limit in size was not established as the largest grafts used were more readily accepted than smaller grafts.     

Effects of split-thickness and full-thickness skin grafts on secondary graft contraction in horses.

Full-thickness, circular (4-cm diameter) cutaneous wounds were created on the metacarpi and metatarsi of 6 horses. Immediately after wounding, 1 wound on each horse received a meshed, split-thickness skin graft (0.64 mm) obtained from the ventrolateral aspect of the horse's thorax by use of a pneumatic dermatome, whereas a second wound received a meshed, full-thickness skin graft obtained from the pectoral area. In addition, sections of split-thickness and full-thickness grafts were refrigerated in a solution of McCoy's 5A medium, to which equine serum (10%) and gentamicin sulfate solution (16 mg/dl) were added. Ten days after wounding, 1 granulating wound on each horse was grafted with a stored, meshed, split-thickness graft, and 1 granulating wound on each horse was grafted with a stored, meshed, full-thickness graft. Areas of wounds were calculated from photographs taken of wounds on days 1, 5, 10, 15, 20, 25, and 30 after wounding. Time course of contraction was determined by use of a first-order mathematic model of changes in area through time. Rate constants of contraction for fresh or granulating wounds receiving full-thickness grafts did not differ significantly from those for fresh or granulating wounds receiving split-thickness grafts. Rate constants of contraction for grafted fresh wounds, however, were significantly less than those of grafted granulating wounds, regardless of whether a split-thickness or full-thickness graft was applied.     

Effects of hyperbaric oxygen on full-thickness meshed sheet skin grafts applied to fresh and granulating wounds in horses

OBJECTIVE: To determine the effects of hyperbaric oxygen therapy (HBOT) on full-thickness skin grafts applied to fresh and granulating wounds of horses. ANIMALS: 6 horses. PROCEDURES: On day 0, two 4-cm-diameter circular sections of full-thickness skin were removed from each of 2 randomly selected limbs of each horse, and two 4-cm-diameter circular skin grafts were harvested from the pectoral region. A skin graft was applied to 1 randomly selected wound on each limb, leaving the 2 nongrafted wounds to heal by second intention. On day 7, 2 grafts were harvested from the pectoral region and applied to the granulating wounds, and wounds grafted on day 0 were biopsied. On day 14, 1 wound was created on each of the 2 unwounded limbs, and the wounds that were grafted on day 7 were biopsied. All 4 ungrafted wounds (ie, 2 fresh wounds and 2 wounds with 1-week-old granulation beds) were grafted. The horses then received HBOT for 1 hour daily at 23 PSI for 7 days. On day 21, the grafts applied on day 14 were biopsied. RESULTS: Histologic examination of biopsy specimens revealed that grafts treated with HBOT developed less granulation tissue, edema, and neovascularization, but more inflammation. The superficial portion of the graft was also less viable than the superficial portion of those not treated with HBOT. CONCLUSIONS AND CLINICAL RELEVANCE: The use of HBOT after full-thickness skin grafting of uncompromised fresh and granulating wounds of horses is not indicated.     

Paranasal sinus surgery through a frontonasal flap in sedated, standing horses

OBJECTIVE: To report experience with paranasal sinus surgery through a frontonasal flap in sedated, standing horses. STUDY DESIGN: Treatment of 10 horses with naturally occurring paranasal sinus disease through a frontonasal bone flap created with the horses standing. ANIMALS: Ten adult horses. METHODS: After restraint and sedation, local anesthetic was injected subcutaneously along the proposed incision line over the conchofrontal sinus and was instilled into the sinuses through a small hole created in the frontal bone. A 3-sided, rectangular, cutaneous incision that extended through the periosteum was created over the frontal and nasal bones. The incision was extended into the conchofrontal sinus using a bone saw, and the base of the flap, on the midline of the face, was fractured. The sinuses were explored, and the horse was treated for the disease encountered. The flap was repositioned; subcutaneous tissue and skin were sutured separately. RESULTS: The horses had few signs of discomfort during creation of the bone flap and during disease treatment. Diseases encountered included inspissated exudate in the ventral conchal sinus (five horses), feed and exudate throughout the sinuses (one horse), occlusion of the nasomaxillary aperature (one horse), polyp (one horse), osteoma (one horse), and progressive ethmoidal hematoma (one horse). CONCLUSION: In selected cases, surgery of the paranasal sinuses can be performed safely on sedated and standing horses through a frontonasal bone flap. CLINICAL RELEVANCE: Performing surgery through a frontonasal bone flap with the horse standing and sedated, rather than anesthetized, eliminates risks and expense of general anesthesia.     

Viability of split-thickness skin grafts attached with fibrin glue.

Full-thickness, circular, cutaneous wounds (4 cm diameter) were created on metacarpi and metatarsi of 5 horses. On day 6, all 4 wounds on each horse received a stored autogenous split-thickness sheet graft. Grafts were obtained from the horse's ventrolateral thorax with a pneumatic dermatome at the time the cutaneous wounds were created. Grafts were coapted to the granulation bed of 2 wounds of each horse with fibrin glue. Grafts were coapted to the cutaneous margin of all 4 wounds of each horse with cyanoacrylate glue. Bandages were changed daily until the study ended at 14 d. When the bandages were changed, ointment containing neomycin, polymyxin B, and bacitracin was applied to all wounds. The viable area of graft was measured on post-grafting d 14 and calculated with a micro-processor. Split-thickness sheet-grafts attached to granulation beds on the metacarpi and metatarsi with fibrin glue had no greater survival than did grafts attached without fibrin glue (P > 0.05).     

The Effects of Skin Graft Thickness on Graft Viability and Change in Original Graft Area in Dogs

The viability and change in original graft area of full thickness grafts (FTG) and split thickness skin grafts (STG) placed on fresh and granulating recipient beds were evaluated. Two 6 × 6 cm skin grafts were placed on each side of the trunk in ten dogs. Grafting procedures included FTG and STG on fresh and granulating wounds. Graft viability was determined on the 10th postoperative day by visual inspection. The change in original graft area was evaluated by comparing the original surface area of the grafts with the surface areas of the grafts at 10, 30, 60, and 90 days after surgery. The means graft viability for FTG and STG on fresh beds was 81% and 55%, respectively. FTG and STG on granulating beds had a mean graft viability of 58% and 47%, respectively. The mean percentage of original graft area at 90 days for FTG and STG on fresh beds was 82% and 97%, respectively. FTG and STG on granulating beds had an overall percentage of original graft area of 105% and 130%, respectively. There were no statistical differences found when comparing FTG with STG placed on fresh beds or granulating beds. However, the general trend indicated that FTG had a greater percentage of viability and contracted more than STG in dogs. This is contrary to previous findings.     

Tunnel grafting for wound repair in horses: a novel technique in graft production and placement

There are several skin grafting methods described in the human and animal literature. Currently, there are five types of free grafts used in horses: pinch and punch grafts, split and full-thickness sheet or mesh grafts and tunnel grafts. Published methods of tunnel grafting describe the use of alligator forceps. The alligator forceps create a poor tunnel and are excessively traumatic to the granulation bed. This technique utilised a 13G Jamshidi needle that was placed across the granulation bed and created a uniform tunnel. The Jamshidi needle was atraumatic to the granulation bed increasing the opportunity for graft survival. A twin bladed scalpel allowed for the quick creation of uniform width grafts. Removal of the overlying tunnel ‘roof’ took place 5–14 days later to allow graft expansion. This case series included five horses with distal limb wounds and one with a wither injury. Four horses required general anaesthesia for graft placement and three required general anaesthesia for the removal of the tunnel roof. The acceptance of the grafts varied from 70% to 100%. Graft expansion to cover the granulation tissue took 2–5 months. This case series demonstrates that this technique of graft production and placement is an easy method for achieving successful skin grafting. Compared to other graft types, tunnel grafts are more readily accepted. Cosmetic and functional results achieved are better than those with pinch and punch grafts. Tunnel grafting does not require expensive equipment or advanced training, and in some cases can be performed under standing sedation.     

Incorporation of Fresh and Cryopreserved Bone in Osteochondral Autografts in the Horse

The structural integrity of subchondral bone in fresh and frozen osteochondral autografts was investigated at month 3 in 10 horses. Two osteochondral autografts were harvested from the lateral aspect of the lateral trochlear ridge of the left talus in each of 10 anesthetized horses. Grafts were frozen in 7.5% DMSO. After 14 days, the thawed grafts were press-fitted into drill holes in the trochlear ridges of the right stifles. A fresh graft from the right hock was implanted in each left stifle. To control for the effects of surgery, a fresh graft was transferred from the right stifle to the left stifle. The end result was two grafts in each femoropatellar joint. Fresh and frozen bone grafts maintained a structurally intact support for the cartilage surface. Graft stability and surface congruency were determining factors in the outcome of the grafts. Incorporation of both types of graft was complete at month 3, but remodeling of the fresh grafts was more active.     

Endoscope-guided, transoral axial division of an entrapping epiglottic fold in fifteen standing horses

Objectives— To describe and evaluate the use of a transoral, endoscope-guided technique for transection of an entrapping epiglottic fold in sedated standing horses.
Study Design— Retrospective study.
Animals— Horses (n=16) with epiglottic fold entrapment (EFE).
Methods— Medical records (2005–2006) of 16 horses with EFE were reviewed to determine history, physical and endoscopic examination findings, postoperative complications, and outcome after axial division of EFE using a hooked bistoury, under an endoscopic-guided, transoral approach.
Results— EFE was confirmed by endoscopy. Axial division was successfully performed in 15 sedated, standing horses. One horse had to be anesthetized to complete the procedure. None of the horses made abnormal respiratory noise after surgery and all returned to their intended use. After surgery, 1 horse had a short, deformed epiglottis.
Conclusions— EFE can be axially divided safely and effectively using an endoscope-guided, transoral approach, with the horse sedated and standing.
Clinical Relevance— Endoscopic-guided, transoral axial division of EFE in sedated standing horses is an alternative choice to performing this procedure under general anesthesia.     

Subtotal ostectomy of dorsal spinous processes performed in nine standing horses

OBJECTIVE: To describe and evaluate subtotal ostectomy of dorsal spinous processes (DSP) performed in standing horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Nine adult horses. METHODS: The diseased portions of the DSP were removed with the horses standing and sedated after infiltrating a local anesthetic agent around the affected DSP. Medical records of affected horses were reviewed to determine history, findings of physical and radiographic examination, surgical technique, postoperative complications, and outcome. RESULTS: Five horses had subtotal ostectomy of DSP because of osteomyelitis, and 4 because of impingement and/or fracture of DSP. Affected portions of DSP were removed safely and effectively, with no apparent discomfort to the horses; hemorrhage was minimal. CONCLUSIONS: Subtotal ostectomy of DSP can be performed safely in standing, conscious horses and the risks associated with general anesthesia are eliminated. Hemorrhage is minimal compared to that which occurs when the procedure is performed with horses anesthetized and in lateral recumbency. CLINICAL RELEVANCE: Access and visibility are better when subtotal ostectomy of the DSP is performed with the horse standing rather than anesthetized and in lateral recumbency. Performing subtotal ostectomy of diseased DSP with the horse standing avoids the expense and risks of general anesthesia.     

Small intestinal biopsy and resection in standing sedated horses

Diagnostic laparotomy and laparoscopy are surgical techniques commonly used for the investigation of chronic abdominal disease and weight loss. They can both be usefully carried out in the standing sedated horse, allowing a thorough examination of the dorsal abdominal cavity and biopsies to be harvested. Small intestinal disease is an important cause of weight loss and recurrent colic. Inflammatory or neoplastic bowel disease may not always be apparent grossly and histopathological assessment of full thickness biopsies may be required to provide a definitive diagnosis. Details of cases of 15 horses that underwent small intestinal biopsy or enterectomy while sedated and standing are presented. Three incisional infections occurred causing delayed wound healing. Three horses were subjected to euthanasia before hospital discharge: two had persistent gastric reflux and one had colitis. A further six were subjected to euthanasia in the first 4 months due to their underlying inflammatory bowel condition. One horse was subjected to euthanasia for severe laminitis that was presumed to be caused by treatment with a corticosteroid 4 years later, and one died of acute colic 2.3 years after successful resection and anastomosis. Five horses were alive at the time of review, median 2.7, range 1.2–4.3 years. Overall therefore, 3 (20%) horses died during hospitalisation and 5 (33%) were still alive at the end of the study. Results from this series suggest that minimising the number of intestinal biopsies may reduce morbidity, but the underlying pathological process appears to be the most important prognostic factor for survival. Resection and anastomosis in the standing sedated horse proved feasible.     

Cutaneous habronemiasis in a 9‐year‐old Arab gelding in the United Kingdom

Cutaneous habronemiasis causes ulcerative granulating lesions in the skin of equids. Dramatic exuberant tissue may be seen, which becomes traumatised by the horse. To the authors' knowledge, cutaneous habronemiasis has not previously been documented on the distal limb of horses in the UK. Cutaneous habronemiasis should be considered as a potential differential diagnosis for ulcerative granulating skin lesions on the distal limb of the horse.     

Transpalpebral eye enucleation in 40 standing horses

Objective— To report a technique for eye enucleation in standing sedated horses and to report outcome in 40 horses.
Study Design— Retrospective study.
Animals— Horses (n=40) requiring eye enucleation.
Methods— The eye was enucleated using a transpalpebral technique in 40 horses restrained in stocks and sedated. Anesthesia of orbital structures was provided by local nerve blocks and infiltration of the surgical site with local anesthetic solution.
Results— Affected eyes were successfully enucleated with the horse standing. Short-term complications included moderate swelling (5 horses) and wound discharge (1). Long-term complications were not observed.
Conclusions— A diseased eye can be safely enucleated with a horse standing.
Clinical Relevance— Enucleating an equine eye in the standing position eliminates the risks and costs of general anesthesia.     

Fixation of skin grafts in the horse using stainless steel staples.

Three horses with a chronic wound on the distal part of a leg were treated successfully by grafting. Small split skin grafts were fixed onto pieces of adhesive tape. The tape pieces were spread over and fixed to the granulation surface with stainless steel staples. A tight pressure bandage including strongly compressed cellular rubber was then applied over the wound. The combination of staple fixation and strong pressure proved effective in immobilising the skin graft. It was stressed that a firm covering of granulation tissue was a prerequisite for success and therefore the technique should not be used for fresh wounds.     

Sternal bone biopsy in standing horses

OBJECTIVE: To develop a technique for sternal bone biopsy in standing horses. STUDY DESIGN: Experimental study. ANIMALS: Five adult horses. METHODS: Horses were restrained in a standing stocks and sedated. The sternal biopsy site, identified by ultrasonographic examination, was clipped and prepared for aseptic surgery and infiltrated with local anesthetic. An electric bone biopsy drill (Osteocore; Institut Straumann AG, CH-4437, Waldenburg, Switzerland)), which yielded 4-mm-diameter bone specimens, was used to obtain sternal biopsies through a small skin incision. Sections (7 microm) of the bone specimens were stained with toluidine blue and Goldner's green trichrome and observed microscopically to determine suitability for histological and histomorphometric evaluation. RESULTS: The most suitable sternal biopsy site was at the 4th or 5th sternebra. The surgical procedure was easy to perform and well tolerated by the horses, and adequate samples were obtained on the first attempt. The only complications were incisional edema in all horses and wound drainage in 1 horse. CONCLUSIONS: Sternal bone biopsy may be successfully performed in standing horses, and the technique described in this report yields architecturally intact bone specimens. CLINICAL RELEVANCE: The sternum is an accessible site for cancellous bone biopsy specimens in standing horses.     

The modified Meek technique as a novel method for skin grafting in horses: evaluation of acceptance, wound contraction and closure in chronic wounds

REASONS FOR PERFORMING STUDY: The acceptance of skin grafts in horses is unpredictable and the final cosmetic result can be disappointing. Besides movement and infection, graft failure is often caused by chronic inflammation, inherently present during second intention healing of limb wounds in horses. In human burns affected by infection and inflammation, the acceptance of the island skin grafts of the modified Meek technique appeared to be better than meshed sheet skin grafts. HYPOTHESIS: The percentage take of Meek micrografts is higher than of other techniques; and rates of both wound contraction and epithelialisation are increased. METHODS: Large traumatic limb wounds of 13 horses healing by second intention were grafted using the modified Meek technique. Photographs of the wounds were taken at set intervals. Wound areas, and areas of acceptance and rejection were determined using a digital image post processor (Scion Image). The percentages of take, wound contraction and epithelialisation were calculated. RESULTS: The initial mean wound area was 7500 mm2. Graft acceptance was mean +/- s.d. 93.7 +/- 5.9%. Wound closure was due to contraction (55.2 +/- 11.1%) and epithelialisation (44.8 +/- 11.1%) and resulted in a 96.7 +/- 3.6% reduction of the initial wound area 29.1 +/- 6 days after grafting. All wounds showed functional and cosmetic healing. CONCLUSIONS: The method for skin grafting in horses achieved higher percentages of take than reported previously and consistent cosmetic and functional results. The grafts increased not only the rate of epithelialisation but also had a strong positive effect on wound contraction, resulting in rapid closure and smaller scars. POTENTIAL RELEVANCE: The modified Meek technique proved to be a novel technique for skin grafting equine wounds in clinical practice, which can be performed easily. The molecular background of the increase of wound contraction by the grafts may provide a clue in the search for medicinal stimulation of wound contraction during second intention healing.     

Tissue Engineering in Wound Repair: The three “R”s—Repair,Replace, Regenerate

Horses are predisposed to traumatic wounds that can be labor intensive and expensive to manage. Skin has a considerable potential for efficient and functional repair however, while cutaneous repair is a regenerative process in the fetus, this capability declines in late gestation as inflammation and scarring alter the outcome of healing. The historical gold standard for replacement of lost skin is the autologous skin graft. However, the horse's lack of redundant donor skin limits the practicality of full‐thickness grafting to smaller wounds; moreover, graft failure is relatively common in equine patients as a result of infection, inflammation, fluid accumulation beneath the graft, and motion. Tissue engineering has emerged as an interdisciplinary field with the aim to regenerate new biological material for replacing diseased or damaged tissues or organs. In the case of skin, the ultimate goal is to rapidly create a construct that effects the complete regeneration of functional skin, including all its layers and appendages. Moreover, an operational vascular and nervous network, with scar‐free integration within the surrounding host tissue, is desirable. For this to be achieved, not only is an appropriate source of cells required, but also a scaffold designed from natural or synthetic polymers. The newly created tissue might finally meet the numerous needs and expectations of practitioners and surgeons managing a catastrophic wound in a horse     

Management of exuberant granulation tissue

Exuberant granulation tissue is common in large, lower limb wounds of horses, particularly horses of large body size. Methods of control include chemical cautery, cryogenic surgery, and surgical resection. Surgical resection is preferred because it is easy to perform, provides tissue for histologic evaluation, and preserves the epithelial margin. Effective treatments to prevent the formation of granulation tissue include leaving granulating wounds open to the air or, possibly, bandaging with topical steroids. Bandaging or casting may promote exuberant granulation tissue in wounds in which it has already formed, but bandaging and casting are still important in the early management of lower limb or hock wounds in horses. The use of skin grafts or delayed secondary wound closure is frequently necessary to prevent the recurrence of exuberant granulation tissue.     

Standing Lateral Thoracotomy in Horses: Indications,Complications, and Outcomes

Objective: To describe the indications for, complications arising from, and outcome of horses that had standing lateral thoracotomy for pleural or pericardial disease. Study Design: Case series. Animals: Horses (n=16). Methods: Medical records (January 1990–December 2008) of sedated standing horses that had lateral thoracotomy were reviewed. Clinical and surgical findings, perioperative and short‐term complications were recorded. Long‐term (>6 months) outcome was determined through telephone conversations with owners and veterinarians. Results: Mean (±SD) horse age was 6.6±5.3 years (range, 1–15 years). Thoracotomy was most commonly for treatment of recurrent or chronic pleural infection (94%). Anaerobic bacteria were frequently isolated from pleural effusion associated with pleuropneumonia (63%). Right lateral intercostal thoracotomy was performed in 13 horses (82%); intercostal muscle myectomy in 5 horses; and rib resection in 1. Perioperative complications were hemipneumothorax (2 horses) and short‐term complications included cellulitis and abscessation of the thoracotomy site (6 horses). Fourteen (88%) horses survived to discharge and 46% of horses that survived returned to their previous level of athletic activity. Conclusions: Lateral thoracotomy is well tolerated by standing sedated horses with minimal perioperative and short‐term complications. Clinical Relevance: Standing lateral thoracotomy should be considered for the treatment of complicated pleuropneumonia in horses.     

Kinetics of healing of grafted and nongrafted wounds on the distal portion of the forelimbs of horses.

Full-thickness, circular, cutaneous wounds (5 cm in diameter) were created on the distal portion of the forelimbs of 6 horses. One wound on each horse was treated with 6 full-thickness punch grafts that were obtained from the horse's neck with a 6-mm skin biopsy punch and inserted in the graft sites on day 14 after wounding. The wound on the contralateral limb was not grafted. A combination of ticarcillin disodium and clavulanate potassium was applied to the wounds when bandages were changed to control bacterial infection. Areas of each wound were measured on days 1, 7, 9, 11, 13 through 15, 17 through 22, 24, 26, 29, and 32 after wounding. Three distinguishable phases of healing were observed (expansion, contraction, and epithelialization), and the time course of each phase was evaluated, using formulas of first-order processes. Rate constants of each phase were not significantly (P less than 0.05) affected by punch grafts.