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Wound healing is achieved through orchestrated phases that must occur in the proper sequence and time. Many factors impair normal healing by interfering with one or more of its phases. This chapter reviews the most important factors known to negatively affect healing and describes the mechanisms whereby they exert their detrimental effects. The factors discussed include patient-related factors (horse versus pony, age, nutritional status, disease, and tissue perfusion) and wound-related factors (causes and types of wounds, age and location of the wound, involvement of structures other than skin, nature of the wound, previous treatment, neoplastic transformation, and bioburden). A better understanding of the influence of these factors on repair may lead to a therapeutic approach that negates or diminishes their effects, thereby improving healing and resolving non-healing wounds.

The aim of wound management is to optimize healing in an effort to return the horse to its previous function as rapidly as possible, while respecting the financial constraints of the owner. Infection, with its associated excessive or inappropriate inflammation, is the single most likely cause of delayed healing of wounds healing by second intention. Effective wound preparation, exploration, cleansing via irrigation, and debridement are central to reducing the incidence of infection and promoting uncomplicated healing of accidental wounds. Antimicrobial drugs should be used only when there is clinical evidence of infection or when development of an infection would be life-threatening or career-ending for the patient. Although empiric broad-spectrum antimicrobial therapy may be used initially, definitive selection of antimicrobial drugs should be based on the results of bacterial culture and sensitivity testing of isolates. The use of antimicrobial drugs in surgical wounds should never replace aseptic and atraumatic surgical technique. Where there is evidence of formation of biofilm, repeat debridement and topical administration of antimicrobial drugs should be central to any treatment plan.

Summary Ileal bypass by re-section and jejunocaecostomy is a commonly performed surgery in horses, but has a reportedly lower success rate than other small intestinal surgeries. Lower success rates and chronic problems with diarrhoea, weight loss, protein, sugar and fat malabsorption, and Ca/P imbalance occur in man. The purpose of this study was to investigate changes in bodyweight, nutrient digestion and absorption, and serum and urine composition in horses before and 3, 12 and 27 weeks after ileal resection and side-to-side jejunocaecostomy. Four adult, healthy horses had a baseline CBC; serum creatinine, cholesterol, Na, K, Cl, Mg, Ca, P; digestion trial; xylose and fat absorption test; and serum total bile acid test. Digestion of dry matter, crude protein, total plant cell wall, cellulose, hemicellulose, and lignin; and urinary fractional excretions of Na, K, Cl, P and Ca were calculated. A one-way analysis of variance compared baseline values to those obtained after caeliotomy and jejunocaecostomy (P

Numerous topical wound medicants are available today. Very few of these products have been tested in the horse. Due to the unique nature of wound healing in the distal limbs of horses (carpus, tarsus and distad), many beneficial effects of these medicants seen in other species and in vitro have not been reproduced in equine limb wounds. There is an abundance of literature regarding topical wound medicants; however, the findings of these studies are quite variable, in general. Many wound care articles have questioned the routine use of topical medications, preferring the concept of moist wound healing in which the body produces all the substrates necessary for adequate wound healing. This article outlines many of the common products that are available to equine practitioners and provides current information regarding their use in wound healing. Unfortunately no product or substrate has been shown to be superior for equine wound management. That being said, the information provided in this article will attempt to provide the practitioner with information necessary to make educated decisions regarding the selection of topical medicants for wound care.

Currently, there are a variety of wound dressings available ranging from passive adherent/nonadherent to interactive and bioactive products that contribute to the healing process. Many of the newer dressings are designed to create a moist wound healing environment which allows the wound fluids and growth factors to remain in contact with wound, thus promoting autolytic debridement and accelerating wound healing. Even with substantial advancements in wound dressings it appears that no single material can produce the optimum microenvironment for all wounds or for all the stages of the wound healing process. The intent of this report is to provide a review of currently available dressings, their physical characteristics and to describe their best use as it relates to the condition of the wound (clean, contaminated or infected) and the phases of wound healing.

Objective—To evaluate the outcome of horses with large fragments of the extensor process of the distal phalanx that were removed by use of arthrotomy. Design—Retrospective study. Animals—14 horses with large fragments of the extensor process of the distal phalanx. Procedure—Medical records for horses with large fragments of the extensor process that were removed by use of arthrotomy were reviewed. Data retrieved from medical records included signalment, use of horse, affected limb, lameness history, lameness examination findings, radiographic findings, surgical technique, and outcome. Follow-up evaluation was obtained by telephone interview. Results—Most affected horses were < 5 years old and had a history of chronic lameness. Lameness grade ranged from 1/5 to 4/5. Fragments involved 20 to 45% of the dorsopalmar articular surface of the distal phalanx. Eight of 14 horses had a successful outcome. Outcome was not associated with age, duration or severity of lameness, or fragment size. Conclusions and Clinical Relevance—Despite involvement of a large portion of the articular surface and use of arthrotomy, joint instability and permanent soft tissue injury was not a problem in most horses. Outcome may be improved by selection of horses with lameness of < 2 years' duration and careful management after surgery. A fair prognosis may be anticipated for removal of large fragments of the extensor process via arthrotomy. (J Am Vet Med Assoc 2000; 217:1351–1355)

In 12 sheep (24 forelimbs), a 12 mm section of flexor digitorum superficialis tendon was removed. The tendons were repaired with (1) suture only (control group, n = 8), (2) suture plus implanted nonwoven polyester fiber (NWF group, n = 8), and (3) suture plus implanted nonwoven fiber and chitin complex (CP group, n = 8). All tendons were immobilized for 6 weeks. Macroscopic and histomorphometric evaluations were performed on two limbs from each treatment group in weeks 1, 3, 6, and 12. Macroscopic findings showed no significant differences among the three groups in any parameters. At the implant area, histomorphometry indicated that immature and intermediate fibroplasia was significantly greater in the CP group compared to the NWF group in week 1 and in weeks 3 and 6, respectively. In the area surrounding the implant, there were no significant differences among the three groups.

Traumatic injuries to the head region of the horse are a common presenting complaint. Because of a copious blood supply, these wounds typically exhibit a tremendous capability for healing. By following the basic principles of wound management and employing a few techniques unique for specific injuries, the healing of these wounds can result in a satisfactory outcome.

An independent validation study was performed to assess the predictive performance of two multivariable logistic regression models which had been developed to evaluate both prognosis and the need for surgery in equine colic patients. The validation study prospectively collected 730 equine colic cases at 16 different locations over a 15-month period. Bayes' theorem was used to generate post-test (posterior) probabilities for each outcome. Likelihood ratios (LR) for death and the need for surgery were calculated for each horse using the two logistic regression equations. The proportion of surgical patients and the case fatality rate of colic cases seen at each institution were used to estimate the pre-test odds of the need for surgery and the pre-test odds of death, respectively. The post-test odds then were generated by calculating the product of the pre-test odds and the LR (test-odds). The post-test odds than were simply converted to the more intuitive post-test or posterior probabilities. Hosmer Lemeshow goodness-of-fit chi square statistics (GOFCS) were calculated using equal-sized deciles of risk for both models. The prognosis model fit the validation data well (χ2 = 11.2, df = 10, 0.3 < P < 0.4), while the need-for-surgery model fit the validation data poorly (χ2 = 39.0, df = 10, P = < 0.001). An additional validation procedure was used in which the post-test probabilities were ranked and then grouped into ten increments based on the following cut-points of post-test probability: 0−

Summary Fifty-five horses were presented to Colorado State University Veterinary Teaching Hospital between 1st of January 1980 and 31st of December 1989 for treatment of distal limb lacerations involving flexor tendons (n = 35) or extensor tendons (n = 20). Of the 35 flexor tendon lacerations, 11 horses were killed without treatment and 24 horses were treated. Twenty-two horses were included in determining outcome. Four (18 per cent) returned to their original level of use, nine (41 per cent) returned to limited riding, seven (32 per cent) returned to breeding or pasture soundness and two (9 per cent) were killed. Eighteen of the 20 horses with extensor tendon lacerations underwent treatment and 15 had sufficient follow-up to determine outcome. Seven (47 per cent) returned to their original or intended use, five (33 per cent) returned to limited use, one (7 per cent) was used for breeding and two (13 per cent) were killed. Results for horses with extensor tendon lacerations support previous reports that these injuries can be treated successfully. Results for horses having flexor tendon lacerations were better than in previous reports.

A survey of 1965 equine colic cases was conducted from August 1985 to July 1986 ten equine referral hospitals located througout the U.S.A. Two-thirds of the cases were randomly selected for model development (1336), while the remaining cases (629) were used only for subsequent validation of the model. The following outcomes were defined: (1) died or killed prior to discharge from the hospital; or (2) alive at the time of discharge. Only variables which were significant (P

Objective—To determine the clinical applications, short and long-term survival, and complications of using transfixation pin casts for treatment of comminuted phalangeal fractures in adult horses. Design—Retrospective case series. Animals—20 horses. Procedures—Medical records were reviewed to obtain information regarding signalment, fracture location, treatment methods, complications, and short-term survival (discharge from hospital). Long-term follow-up information was obtained via contact with owners or trainers. Results—12 fractures were in a hind limb, and 8 were in a forelimb. Fourteen fractures occurred in a middle phalanx, and 6 occurred in a proximal phalanx. Eleven fractures were treated with internal fixation combined with transfixation pin casts, and 9 fractures were treated with transfixation pin casts alone. Transfixation pin casts were maintained for a mean of 52 days (median, 49 days; range, 1 to 131 days). Fourteen (70%) horses were discharged from the hospital, whereas 6 (30%) were euthanized during the treatment period. Reasons for euthanasia included secondary fracture of the third metacarpal or metatarsal bone, avascularity of the distal aspect of the limb associated with an open fracture, and displacement of the fracture after transfixation pin cast removal. A significantly greater number of horses was discharged from the hospital when the transfixation pin cast was maintained for > 40 days, compared with those in which the transfixation pin cast was maintained for < 40 days. Conclusions and Clinical Relevance—Results suggested that horses should be maintained in a transfixation pin cast for a minimum of 40 days, as this was associated with an increase in short-term survival without an increased risk of catastrophic failure.

The head from three horses euthanized due to diseases unrelated to the head and neck was imaged using computed tomography (CT). Gross cross-sectional slices of equine head #1 and skeleton of equine head #2 were compared with the CT images of the three equine heads to identify normal structures of the cranium, brain, paranasal sinuses, nasal cavity, and teeth. Labeled transverse CT images of the equine head are presented sequentially as a reference for normal anatomy.

Objective— To report the history, clinical findings, and outcome of horses with idiopathic focal eosinophilic enteritis associated with acute small intestinal obstruction. Study Design— Retrospective study. Animals— Six horses with idiopathic focal eosinophilic enteritis. Methods— Retrospective review of medical records of horses with idiopathic focal eosinophilic enteritis, with acute abdominal pain and small intestinal obstruction, associated with a focal region of eosinophilic enteritis of unknown cause. Information retrieved from the medical records included signalment, physical examination, laboratory findings, surgical procedure, histologic diagnosis, and postoperative management. Outcome was determined by telephone communication with owners. Results— Six horses met the selection criteria. Horses had persistent pain, distended small intestine, and nasogastric reflux. Idiopathic focal eosinophilic enteritis lesions associated with a small intestinal obstruction were treated surgically by intestinal resection and anastomosis or wedge resection. There were no observed complications associated with extension of the disease from the lesion site. Five horses were alive at follow-up 5 to 60 months after surgery. Conclusions— Although the cause of these focal eosinophilic enteritis lesions is unknown, the long-term outcome after lesion resection was favorable. Clinical Relevance— Small intestinal obstruction associated with a focal eosinophilic enteritis lesion may be a cause of acute abdominal pain in horses. Horses apparently have a good prognosis after lesion resection.

Objective— To describe a tenoscopic approach to the carpal sheath for desmotomy of the accessory ligament of the superficial digital flexor tendon. Study Design— The surgical procedure was developed with use of normal forelimbs from equine cadavers and experimental horses. Animals or Sample Population— Twelve equine cadaveric forelimbs, 4 forelimbs from 2 horses anesthetized for terminal surgical laboratories, and 10 forelimbs from five experimental horses were used. Methods— The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal was made approximately 2 cm proximal to the distal radial physis for arthroscope insertion. An instrument portal was made approximately 0.2 cm proximal to the distal radial physis. After flexion of the limb to 90°, the accessory ligament of the superficial digital flexor tendon was palpated and desmotomy was performed. Cadaveric limbs were dissected to confirm complete desmotomy. Experimental horses were monitored for short- (perioperative) and long- (4 weeks) term postoperative complications. Results— A tenoscopic approach to the carpal sheath provided adequate surgical access to the accessory ligament of the superficial digital flexor tendon for desmotomy. Most of the accessory ligament of the superficial digital flexor tendon could be easily seen within the sheath, except for the proximal 2 cm that could be readily palpated and subsequently transected. Important technical considerations were location of the arthroscope portal, adequate sheath distention, limb flexion to 90°, and desmotomy location. It was beneficial, but apparently not essential, to avoid the proximal perforating vessel. Postoperatively, some horses had swelling but were not lame and had normal range of motion of the carpus. Conclusions— Desmotomy of the accessory ligament of the superficial digital flexor tendon could be performed by using a lateral tenoscopic approach to the carpal sheath. Clinical Relevance— Desmotomy of the accessory ligament of the superficial digital flexor tendon by using a tenoscopic approach to the carpal sheath is an alternative technique to the medial incisional approach.

Objective—To describe the tenoscopic anatomy of the carpal sheath of the flexor tendons (carpal sheath) viewed from a lateral approach. Study Design—Tenoscopic observation of structures within the carpal sheath subsequently confirmed by dissection. Animals or Sample Population—12 equine cadaveric forelimbs. Methods—The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal for the arthroscope was made approximately 3 cm proximal to the distal radial physis and 2.5 cm caudal to the radius between the tendons of the ulnaris lateralis and lateral digital extensor muscles. Results—A lateral tenoscopic approach was adequate to identify all structures within the carpal sheath. From proximal to distal, structures identified using this approach were the radial head of the deep digital flexor muscle, accessory ligament of the tendon of the superficial digital flexor muscle, distal radial physis, tendons of the superficial and deep digital flexor muscles, accessory carpal bone, antebrachiocarpal and middle carpal joints, and vincula of the tendon of the deep digital flexor muscle. Conclusions—A lateral tenoscopic approach offered an easy, repeatable entry into the carpal sheath and allowed good observation of all structures within the sheath except for the medial borders of the tendons of the deep and superficial digital flexor muscles. Clinical Relevance—Applications of a lateral tenoscopic approach to the carpal sheath include diagnostic procedures, lavage and synovial resection for septic tenosynovitis, desmotomy of the accessory ligament of the tendon of the superficial digital flexor muscle for flexural deformity or tendinitis, and removal of osteochondromas from the distal radial metaphysis.

Objective- The purpose of this study was to determine whether detection of bacterial contamination of ventral midline incisions was predictive of postoperative incisional complications in horses undergoing exploratory celiotomy for colic. Study Design- Prospective study. Animal or Sample Population- Horses that had ventral median celiotomies for colic at Colorado State University between May 1, 1991 and April 30, 1993 were studied prospectively. Complete information was obtained on 66 horses. Methods- Bacterial cultures were obtained from ventral midline incisions at surgery. Information regarding the type of surgery performed (celiotomy vs celiotomy plus enterotomy or enterectomy), preoperative total nucleated cells and presence of a left shift, postoperative fever (>38.5°C), incisional drainage, incisional herniation, and outcome were obtained from medical records. Additional information concerning incisional drainage, herniation, and survival was obtained at a minimum of 18 months after surgery. Results- Examination of odds ratio (ORs) and confidence intervals (CIs) revealed that a celiotomy plus enterotomy or enterectomy was positively, but not significantly, associated (OR > 1) with positive culture results, presence of incisional drainage and incisional herniation. A significant association between incisional drainage and hernia formation was found; odds of incisional herniation were 62.5 times greater in horses that had incisional drainage. Incisional drainage and herniation were negatively associated with patient survival. The later association was significant (OR = 0.18, P=.04). Conclusions- This study indicated that detection of bacterial contamination at incisional closure by the swab culture technique was not beneficial in the prediction of postoperative incisional problems in horses undergoing colic surgery. Incisional drainage or infection appeared to be associated with hernia formation. Clinical Relevance- Immediate treatment of incisional drainage or methods to prevent incisional infections may decrease hernia formation.

In nine horses (18 forelimbs), a 3 cm section of superficial digital flexor tendon was removed and the tendons were repaired with immobilization for 6 weeks and (1) no suture (n = 6); (2) a double locking loop tenorrhaphy with carbon fiber (n = 6); or (3) a double locking loop tenorrhaphy with size 2 nylon suture (n = 6). Clinical assessment, gross evaluation, morphometry, histology, and mechanical testing were performed on two limbs from each treatment group at weeks 6, 12, and 24. At weeks 6 and 12, the unsutured tissue was less mature than the tissue sutured with nylon. By week 24, the carbon fiber repair had breaking stress (mean, 12.5 M Pa) similar to the unsutured repair (mean, 10.6 M Pa). There was necrosis and a granulomatous foreign body reaction around the carbon fiber. The nylon suture repair had significantly greater strength per unit area (mean breaking stress, 20.4 M Pa) because of a smaller area of repair tissue in the gap (mean, 3.6 cm2). At week 24, the nylon suture repair tissue was the most mature with the least inflammation of the three repair methods. A nylon double locking loop suture was the preferred method for equine flexor tenorrhaphy of a tendon gap because of greater breaking stress, histologic maturity, biocompatibility, and the adequate functional and cosmetic outcome.

Thirty-six superficial digital flexor tendons from nine fresh equine cadavers were transected and sutured with size 2 monofilament nylon. Nine tendons were repaired with each of four suture patterns: single-locking loop, double-locking loop, triple-locking loop, or three-loop pulley. The times required for application, tensile strengths, resistance to distraction (gap), and modes of failure were analyzed. The mean times required were: single-locking loop, 3 mins, 15 secs; double-locking loop, 4 mins, 15 secs; triple-locking loop, 10 mins, 50 secs; and three-loop pulley, 4 mins. The double-locking loop, triple-locking loop, and three-loop pulley suture patterns were stronger than the single-locking loop. The triple-locking loop and three-loop pulley patterns were close in strength and only the triple-locking loop was stronger than the double-locking loop. The three-loop pulley had the greatest resistance to gap formation and its mode of failure was different from the others. The three-locking loop suture patterns failed by suture breakage but the three-loop pulley failed first by suture pull-out and then by suture breakage.

Summary A study was undertaken to evaluate the significance and mechanism of reperfusion injury in the equine large colon following 1 h of haemorrhagic strangulation obstruction (HSO) or ischaemic strangulation obstruction (ISO) and to assess the effect of treatment with dimethyl sulphoxide (DMSO). ISO or HSO were created 40 cm from the pelvic flexure and maintained for 60 mins under general anaesthesia. Normal saline or 20 per cent DMSO (1g/kg bodyweight) was administered intravenously 10 mins prior to the end of the ischaemic period. Four groups of four horses in a 2 times 2 factorial design were used. Treatments of HSO or ISO and DMSO given (yes or no) were utilised. Intestinal wall biopsies and right colic arterial and venous blood samples were taken at 0, 60, 90 and 120 mins following initiation of the obstructions. Histological evaluation of the intestine using haematoxylin and eosin stained sections and immunohistochemical staining for albumin were performed. Mucosal and serum reduced glutathione (GSH) and oxidised glutathione (GSSG) levels and the amount of lymphatic dilatation with albumin and submucosal pooling of albumin were used as indirect measures of oxygen free radical production. Histopathological changes were minimal after 1 h of either type of ischaemia. Progressive changes during the post ischaemic period were minimal for ISO and moderate for HSO. Serum GSH and GSSG levels were not detectable. There was no demonstrable benefit of DMSO treatment as assessed by histology, immunohistochemistry or preservation of GSH levels in the mucosa. In conclusion, a reperfusion injury following 60 mins of ischaemia could not be detected in this study.

Subtotal dorsal cervical laminectomy was used to relieve spinal cord compression due to cervical vertebral malformation in 16 horses. The majority were Thoroughbred or Quarter Horse males, 1 to 4 years old. The caudal cervical vertebrae were involved in all but two instances. A Funkquist type B laminectomy was performed and the defect filled with a free autogenous nuchal fat graft. All horses recovered from surgery without complication or deterioration in neurological status. Neurological improvement occurred in 12 cases, including six that became sound. Three horses fractured a vertebral articular process and were euthanized. A modification to the shape of the laminectomy was adopted to reduce this complication.

Lateral or medial luxation of the metacarpophalangeal or metatarsophalangeal (fetlock) joint in 10 horses is presented. Closed and open fetlock luxation each occurred in five horses. Horses were treated by cast immobilisation after debridement of soft tissue and joint lavage in cases of open luxations. Suture apposition of a ruptured collateral ligament was attempted in three cases. Antibiotic therapy was used in all cases of open fetlock luxation but non-steroidal anti-inflammatory medication was used inconsistently. Whether closed or open, fetlock luxations had a good prognosis for return to breeding status. After treatment, seven horses were used for breeding, one horse was ridden for nine years, one horse remained lame and was destroyed and one horse was lost to follow up.

Equine cervical vertebral malformation may result in spinal cord compression that, until recently, has been treated medically. Two descriptions of dorsal laminectomy in the horse indicated the technique could be disastrous, even in the normal horse, and postoperative improvement was variable. In the technique described here, the horse is placed in an oblique lateral position with the neck ventroflexed. A dorsal midline incision is used to expose the cervical vertebrae. Following removal of the soft tissues overlying the dorsal laminae, a Funkquist type B laminectomy is performed. Ligamentum flavum scar tissue, articular facets, and joint capsule are trimmed if they are contributing to the spinal cord compression. The bony defect is filled with a nuchal fat graft, and the surgical site is drained for 4 to 5 days by a suction drainage apparatus. The technique is evaluated in two accompanying articles.

A muscle separating approach with tenotomy of the teres minor was used to expose osteochondritis dissecans lesions in the shoulder joints of five horses. Horses selected for surgery were severely lame or had a long history of lameness. Adequate surgical access allowed removal of cartilage flaps, curettage of the subchondral bone, and in one horse, the removal of an osteocartilaginous free body. Surgical wounds healed by primary intention; one horse developed a seroma that was drained. Three of the five horses were clinically sound 3 months following surgery. Two other horses were pasture sound but lame after extensive athletic activity.

The selection of a suture material, in the past, was based primarily on habit, guesswork and physical properties. This is understandable because there was a limited number of materials to select from and the interaction of suture material with tissues was not understood.

Incarceration of the small intestine through a rent in the gastrosplenic ligament was diagnosed in five horses. Three affected horses were mature males and two were mature females. Persistent moderate to severe abdominal pain, elevated heart rate, congested mucous membranes, serosanguineous peritoneal fluid, and distended small intestine on rectal examination were consistent findings. Exploratory celiotomy or gross necropsy examination showed the incarcerated intestine to be distal jejunum or ileum. In all horses, the intestine had herniated cranially through the rent in the gastrosplenic ligament. The incarcerated intestine was situated lateral to the stomach and craniolateral to the spleen. Three horses underwent exploratory celiotomy, and the incarcerated small intestine was reduced by gentle traction and then resected. Two of these horses were alive more than 2 years postoperatively without recurrence of signs of abdominal pain, and one was euthanized because of dehiscence of the abdominal incision. Two horses were euthanized without surgical intervention, and necropsy examination revealed a recent rent in the gastrosplenic ligament. This condition should be considered in the differential diagnosis of causes of small intestinal strangulation and obstruction in the horse.

Osteochondritis dissecans (OCD) and subchondral cyst-like lesions in 13 shoulders of 11 horses were treated arthroscopically by curettage and lavage. Lameness decreased in all 11 horses. Nine horses were sound, five of them athletically sound, after 5 to 20 months. Complications included the development of subchondral cyst-like lesions and signs of degenerative joint disease. Arthroscopic surgery of the equine shoulder can be done through two portals, one for the arthroscope and one for an instrument. A few hand instruments such as a probe, Ferris-Smith rongeurs, and small, large, and right-angled curettes are needed to debride most lesions. Motorized equipment can expedite the process.

A Hansen type ll intervertebral disk protrusion was diagnosed in an 18-year-old horse with signs of progressive ataxia and paresis. A soft tissue mass dorsal to the C6-C7 intervertebral disk space was identified at myelogram and found to be an intervertebral disk protrusion with enlarged dorsal annulus fibrosis at surgery. Surgical decompression was achieved using a ventral approach to the caudal cervical vertebrae, an approach limited in its application by the vertebral venous sinuses. Neurological signs remained unchanged for 3 days and then deteriorated. The horse was euthanized.

Segments of jejunum that had been subjected to ischemia 1 month previously were resected en bloc in six horses. Everted end-to-end anastomoses were performed by application of double rows of stainless steel staples. The anastomotic sites were examined at 3 weeks, 3 months, 6 months, and 8 months postoperatively. All but one of the horses experienced colic at some point after the second postoperative week. At 3 weeks, there was extensive adhesion and stricture formation associated with the anastomoses. With increasing time postoperatively, there were progressively less severe adhesions and strictures. At 6 and 8 months, there was separation of the muscularis with noticeable thinning at the anastomotic site.

Ten normal horses had approximately 95% of the length of the large colon resected with a side-to-side anastomosis between right ventral and right dorsal colon performed with surgical stapling equipment. Four horses died shortly after surgery of colitis (1 horse) or failure of the TA 90 transection staple line (3 horses). Another horse died 4 months after surgery from disseminated streptococcal infection but had recovered well from the colon resection. Five horses survived long term (18 months) with no clinical evidence of adverse effects of the resection. Surviving horses had weight loss and soft fecal consistency for 3 to 12 weeks after surgery but returned to preoperative values within 12 months. At a second surgery 1 year later (5 horses) or at necropsy 4 months later (1 horse), fibrous omental adhesions were present over the transection staple line in four horses and over the anastomotic staple line in two horses. Omental adhesions to the everted staple line were moderate but not associated with any clinical sequellae. An incisional hernia was present in one horse. The anastomotic stomata measured between 8 and 9 cm, which was 60% of the size of the original surgically created stomata. Failure of the transection staple line occurred in the first three of five horses in which the procedure was attempted due to improper configuration of the staples or crushing of the tissue between the staples. Experience corrected this complication.

Six normal adult horses had large colon resections at the sternal and diaphragmatic flexures. Stainless steel staples were used to close the stumps of the dorsal and ventral colons in all six. Intestinal continuity was restored with a side-to-side anastomosis of the dorsal and ventral colons. Three of these anastomoses were performed with staples, and three with a double inverting suture pattern. After one month, the horses were surgically reevaluated, and the anastomotic sites were examined. There was no significant difference between the stoma sizes in the two groups. No complications were observed with either of the methods. However, the stapling procedure was faster to perform and resulted in less contamination of the surgical field. For these reasons, the authors preferred the stapling technique. No adverse effects from large colon resection were observed. Although the results described are quite good, resection of more extensive portions of the large colon can be more demanding and more problematic.

Subtotal dorsal cervical laminectomy was performed on nine normal horses to evaluate positioning, refine the surgical technique, and assess the immediate and long-term effects of this procedure in the horse. Funkquist type B laminectomies were performed at various levels from C3-C4 to C6-C7. Absorbable gelatin sponge or autogenous nuchal fat was placed over the exposed dura mater. Surgery times varied from 2 to 3 hours, and all horses recovered without complication. Rapid primary intention wound healing occurred, with two horses showing neck pain. All remained neurologically normal. The horses were euthanized 6 weeks, 3 months, or 6 months postoperatively. Myelograms performed just prior to euthanasia demonstrated normal or expanded dye column widths. Necropsy revealed that all surgical sites had healed well. The laminectomy membrane was soft and pliable and could be easily separated from the underlying dura mater when fat was used as interpositional material. When gelatin sponge was used, the laminectomy membrane was firmly bonded to the dura. Spinal cords at the level of laminectomy appeared normal and moved freely within the vertebral canal. Histological evaluation of the laminectomy sites and associated spinal cord revealed no abnormalities attributable to the surgery. It was concluded that dorsal cervical laminectomy can be performed in horses without untoward sequelae. The procedure may be useful for the treatment of equine cervical compressive myelopathies.

Specimens of ligamentum flavum, joint capsule, and dorsal lamina were collected at surgery or necropsy from 25 horses with cervical static stenosis. All horses had myelographic evidence of dorsal compression of the spinal cord caused by soft tissue and/or bone in the caudal cervical area, primarily at C6-7. Most horses also had radiographic evidence of degenerative joint disease of articular facets. Histologically 19 horses had osteosclerosis and cartilage retention in the dorsal lamina, and 24 horses had increased fibrocartilage at the ligamentum flavum attachment to dorsal lamina. The ligamentum flavum and joint capsule had fibrovascular tissue in 20 horses. Fibrocartilaginous tissue, old hemorrhage, and fat necrosis were not unusual. One horse each had a synovial cyst, eosinophilic granulomas in the joint capsule, and osteochondrosis of articular facets. These findings indicate that abnormal biomechanical forces or instability of articulations result in stretching and tearing of the ligamentum flavum and joint capsule with subsequent fibrovascular and fibrocartilaginous proliferation, osteosclerosis of the dorsal lamina, and osteophyte formation on the articular facets.

Summary Carbon fibre-polylactic acid composites and monofilament non-absorbable suture material were compared for the repair of surgically transected superficial digital flexor tendons in 10 horses. All surgical wounds healed by first intention. The repaired tendons were enlarged, the carbon implanted tendons being larger than those sutured. The horses were killed at six, eight, 12, 20 or 24 weeks. Greater fibrous thickening occurred in tendons repaired with carbon fibre, especially at 12 weeks postoperatively. Carbon fibre incited a greater histological response with macrophages, lymphocytes, plasma cells, eosinophils and fibroblasts. The fibrous tissue in the repair sites appeared to mature and the collagen to align at a similar rate irrespective of the method of repair. Only that tissue within and immediately surrounding the carbon bundles was immature at six months. There was minimal tendency for carbon filaments to separate and those that did were often surrounded by epithelioid macrophages forming a granuloma. Massive eosinophil concentrations were present between each granuloma. With each sequential test period the sutured tendons became increasingly stronger than the carbon implanted tendons. This may have been because of the immature core of tissue associated with the carbon bundles. No carbon particles were detected in draining lymph nodes.