Evaluation of Carolina Rinse solution as a treatment for ischaemia reperfusion of the equine jejunum.

REASONS FOR PERFORMING STUDY: Ileus and peritoneal adhesions are the most common complications following surgery for small intestinal obstruction. Carolina Rinse (CR) has been shown to decrease reperfusion injury in intestine and other organs. HYPOTHESIS: CR decreases intestinal inflammation and subsequent scarring associated with reperfusion injury. METHODS: CR was infused intra-arterially and applied topically just prior to reperfusion in jejunum exposed to experimental ischemia. Vascular permeability, neutrophil accumulation and serosal scarring were compared in treated and untreated intestine. RESULTS: CR maintained a normal osmotic reflection coefficient and decreased migration of neutrophils into the serosa during reperfusion. After 10 days, treated intestine was normal in appearance with a trend toward less serosal scarring and fibroblast proliferation. There was a significant decrease in fibroplasia at biopsy sites in treated intestine. CONCLUSIONS: Arterial perfusion combined with topical application of CR during jejunal ischaemia decreases immediate reperfusion injury and limits post operative scarring. POTENTIAL RELEVANCE: CR should be used as a local perfusate rather than a systemic treatment; it may best be applied topically and intraluminally to avoid damaging mesenteric arteries. CR should be considered an adjunct treatment as part of overall surgical management and post operative care.

Treatment of ischaemic jejunum with topical and intraluminal Carolina Rinse.

Carolina Rinse Solution (CRS) was applied topically and intraluminally to ischaemic (Group 1; n = 5) and distended equine jejunum (Group 2; n = 5). Mesenteric blood flow, ORC (osmotic reflection coefficient), wet weight to dry weight ratios (WW/DW), serosal thickness, and neutrophil accumulation in the serosa were measured. After 60 min ischaemia followed by reperfusion (Group 1), mesenteric blood flow remained greater than baseline values. The mean ORC was similar to that previously reported in normal bowel or ischaemic intestine treated with CRS by arterial perfusion. The ORC after distention and decompression (Group 2) increased and was similar to that previously reported in a comparable untreated experimental model. The WW/DW after both ischaemia and distention increased compared to specimens collected from noninstrumented jejunum proximal to the experimental segments in the same horses. There was no difference in neutrophil numbers in the serosa of either ischaemic or distended intestine compared to the noninstrumented proximal jejunum. CRS-treated ischaemic intestine maintained microvascular permeability similar to that reported for normal intestine whereas treated distended intestine did not. Combined topical and intraluminal application of CRS to ischaemic intestine may reduce complications due to acute inflammation during reperfusion.

Osteitis of the axial border of the proximal sesamoid bones in horses: eight cases (1993-1999).

OBJECTIVE: To determine clinical, radiographic, and scintigraphic abnormalities in and outcome of horses with septic or nonseptic osteitis of the axial border of the proximal sesamoid bones. DESIGN: Retrospective study. ANIMALS: 8 horses. PROCEDURE: Data collected from medical records included signalment; history; horse use; severity and duration of lameness; results of perineural anesthesia, radiography, ultrasonography, and scintigraphy; and outcome following surgery. RESULTS: Five horses did not have any evidence of sepsis; the other 3 had sepsis of the metacarpophalangeal or metatarsophalangeal joint or the digital synovial sheath. All horses had a history of chronic unilateral lameness. Three of 5 horses improved after diagnostic anesthesia of the metacarpophalangeal or metatarsophalangeal joint; the other 2 improved only after diagnostic anesthesia of the digital synovial sheath. Nuclear scintigraphy was beneficial in localizing the source of the lameness to the proximal sesamoid bones in 4 horses. Arthroscopy of the palmar or plantar pouch of the joint or of the digital synovial sheath revealed intersesamoidean ligament damage and osteomalacia of the axial border of the proximal sesamoid bones in all horses. All 5 horses without sepsis and 1 horse with sepsis returned to their previous uses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that osteitis of the axial border of the proximal sesamoid bones is a distinct entity in horses that typically is associated with inflammation of the associated metacarpointersesamoidean or metatarsointersesamoidean ligament and may be a result of sepsis or nonseptic inflammation. Arthroscopic debridement may allow horses without evidence of sepsis to return to their previous level of performance.

Serosal injury in the equine jejunum and ascending colon after ischemia-reperfusion or intraluminal distention and decompression.

OBJECTIVE: To document morphologic changes that occur in equine intestinal serosa after experimentally induced ischemia and subsequent reperfusion (jejunum, ascending colon) or after intraluminal distention and decompression (jejunum). STUDY DESIGN: Morphologic effects of ischemia-reperfusion or intraluminal distention-decompression determined on the serosal layer of the equine jejunum. The large colon serosa was evaluated after ischemia-reperfusion injury. ANIMALS OR SAMPLE POPULATION: Seven adult horses. METHODS: After induction of general anesthesia and ventral median celiotomy, ischemia was created by arteriovenous (AVO) and lumen occlusion of a 20-cm segment of jejunum and ascending colon for 70 minutes, followed by a 60-minute reperfusion period. Intraluminal distention (25 cm H2O) was created in a second 20-cm jejunal segment and maintained within the abdomen for 120 minutes, followed by a 120-minute decompression period. Seromuscular biopsies were obtained upon entering the abdomen and after the ischemic and reperfusion periods, and after the distention and decompression periods along with corresponding control seromuscular biopsies. Samples were processed and examined by light microscopy, transmission electron, and scanning electron microscopy. RESULTS: Ischemia and reperfusion, and intraluminal distention and decompression, resulted in severe morphologic changes in the seromuscular layer of equine jejunum. A similar period of ischemia-reperfusion caused minimal changes in the ascending colon serosa. CONCLUSION: Adult equine jejunum sustains more serosal damage than the ascending colon after similar periods of ischemia-reperfusion injury. Intraluminal distention and subsequent decompression causes serosal damage in the equine jejunum. CLINICAL RELEVANCE: The small intestine is more susceptible to seromuscular layer damage than the ascending colon.

Effects of intraluminal distention and decompression on microvascular permeability and hemodynamics of the equine jejunum.

OBJECTIVE: To determine whether intraluminal distention and subsequent decompression of the equine jejunum affects intestinal blood flow, hemodynamics, and microvascular permeability. ANIMALS: 5 healthy adu t horses. PROCEDURES: Horses were anesthestized and underwent exploratory laparotomy. Two jejunal segments were identified as sham-operated or instrumented segments. After baseline values were obtained, intraluminal distention was created in the experimental segment to induce an ntraluminal pressure of 18 cm H2O. After 120 minutes of distention, the intestine was decompressed for 120 minutes. Mesenteric blood flow, oxygen delivery, oxygen consumption, microvascular permeability, wet weight-to-dry weight ratio, neutrophil infiltration, and vascular resistance were determined and comparisons made among control, sham-operated, and experimental segments. RESULTS: Mean jejunal blood flow was 21.4 ml/min per kg. There was a significant decrease in mesenteric bood flow to the distended intestine (13.4 ml/min per kg). Blood flow increased significantly during the decompression period (340% of baseline blood flow). Intraluminal distention and subsequent decompression resulted in a significant increase in microvascular permeability, as determined by the osmotic reflection coefficient. Oxygen delivery and oxygen content decreased significantly during the distention period and increased during decompression. Morphologic evaluation revealed a significant increase in edema and neutrophil infiltration after distention and decompression, compared with results for the sham-operated or control segments. CONCLUSIONS AND CLINICAL RELEVANCE: Intraluminal distention and decompression of the equine jejunum results in low-flow ischemia and edema, which may contribute to adhesions and ileus in the postoperative period after surgery for obstructions of the small intestines.

Detachable latex balloon occlusion of an internal carotid artery with an aberrant branch in a horse with guttural pouch (auditory tube diverticulum) mycosis.

An aberrant branch of the internal carotid artery was detected by angiography in a horse with guttural pouch (auditory tube diverticulum) mycosis after the distal portion of the artery had been occluded by use of a detachable latex balloon. A second balloon was placed to eliminate retrograde hemorrhage from the aberrant branch. The horse recovered and returned to its previous activity. Vascular anomalies of the internal carotid artery my be more common than expected, and have resulted in fatal complications during and after surgical treatment in guttural pouch mycosis. Intraoperative identification of vascular anomalies by use of angiography may avoid these fatal complications.

Surgical repair of a diaphragmatic hernia in a racehorse.

A 9-year-old Thoroughbred was evaluated for clinical signs of acute abdominal pain. During laparotomy, a rent in the diaphragm and herniation of the small intestine into the thoracic cavity were detected. Because edges of the rent were smooth and fibrous, which suggested the defect was chronic, the abdomen was closed without repairing the rent. After recurrence of clinical signs, a second laparotomy was performed, during which the intestines were found to have reherniated. The diaphragmatic rent was repaired, using a polypropylene mesh secured with stainless steel staples. The horse recovered and subsequently returned to racing and jumping. A diaphragmatic hernia should be suspected in horses that have moderate to severe signs of abdominal pain for which a definitive cause can not be identified. Thoracic ultrasonography or radiography can be used to confirm the hernia. Diaphragmatic hernias in horses can be successfully repaired using mesh implants secured with staples.

Treatment of impaction colics.

Impactions have been reported in the stomach and all segments of the intestine. Impactions predominately occur just oral to sites of intestinal narrowing or active pacemakers. The most common sites of impaction are in the ileum, the cecum, and the large colon pelvic flexure. The treatment of gastrointestinal impactions depends on the segment affected and the amount of bowel damage which has occurred from distension. Many impactions respond to appropriate administration of analgesics, cathartics, and oral or intravenous fluids. The prognosis for impactions treated medically is better than for those which require surgery.

Diseases and surgery of the cecum.

The cecum is an important site of water and electrolyte absorption, as well as microbial digestion of soluble and insoluble carbohydrates. These functions of the cecum and ascending colon require that ingesta be mixed constantly and retained long enough to complete the digestion of cellulose. Parasites, changes in regional blood flow, diet, and various pharmacologic agents are associated with alterations in normal cecal motility patterns.

Metacarpophalangeal joint synovial pad fibrotic proliferation in 63 horses.

Medical records, radiographs, and sonograms of 63 horses with metacarpophalangeal joint synovial pad proliferation were examined retrospectively. All horses had lameness, joint effusion, or both signs associated with one or both metacarpophalangeal joints. Bony remodeling and concavity of the distodorsal aspect of the third metacarpal bone (Mc3) just proximal to the metacarpal condyles was identified by radiography in 71 joints (93%); 24 joints (32%) had radiographic evidence of a chip fracture located at the proximal dorsal aspect of the proximal phalanx. Fifty-four joints (71%) were examined by ultrasound. The mean +/- SD sagittal thickness of the synovial pad was 11.3 +/- 2.8 mm. Seventy-nine percent of the horses had single joint involvement with equal distribution, between the right and left forelimbs. Sixty-eight joints in 55 horses were treated by arthroscopic surgery. Sixty joints (88%) had debridement of chondral or osteochondral fragmentation from the dorsal surface of Mc3 beneath the synovial pad and 30 joints (44%) had a bone chip fracture removed from the medial or lateral proximal dorsal eminence of the proximal phalanx. Complete or partial excision of both medial and lateral synovial pads was completed in 42 joints. Only the medial synovial pad was excised or trimmed in 21 joints, and 5 joints had only the lateral pad removed. Eight joints in eight horses were treated by stall rest, administration of intra-articular medication and systemic nonsteroidal anti-inflammatory drugs. Follow-up information was obtained for 50 horses treated surgically and for eight horses treated medically. Forty-three (86%) that had surgery returned to racing; 34 (68%) raced at an equivalent or better level than before surgery. Three (38%) of the medically treated horses returned to racing; only one horse raced better than the preinjury level. Horses that returned to racing at a similar or equal level of performance were significantly younger in age than horses returning at a lower level or not racing (P < or = .05). Overall, horses with synovial pad proliferation treated by arthroscopic surgery had a good prognosis for return to racing at a level equal or better than before injury.

Radiographic and arthroscopic findings associated with subchondral lucency of the distal radial carpal bone in 71 horses.

Case records and radiographs of 71 horses with subchondral lucency, without radiographic evidence of fracture, located on the distal radial carpal bone were examined retrospectively. All horses had lameness and/or joint effusion referable to the carpus. Distal radial carpal bone subchondral lucency was found as a solitary lesion or as a lesion concurrent and symmetric to a contralateral distal radial carpal bone chip fracture. The lesion appeared radiographically as a lucency or shadow on the distal dorsal margin of the radial carpal bone and was most evident on the flexed lateromedial and dorsolateral-palmaromedial oblique projections. Sixty-four joints in 55 horses underwent arthroscopic surgery. Surgical findings included osteochondral fragmentation in 44 joints, cartilage fragmentation with subchondral bone softening in 17 joints and cartilage fraying in 3 joints. Corresponding third carpal bone lesions were observed in 18 joints and moderate to severe synovitis was present in 24 joints. Carpal bone subchondral radiolucency without a fracture fragment observed on radiographs indicated cartilage and bone damage. In some cases, small chip fractures (1-2 mm) were present within the cartilage debris examined at surgery, yet were not radiographically visible. Follow-up information was obtained on 50 of the operated horses and 14 nonoperated horses. Forty (80%) of the surgically treated horses returned to racing, with 34 (68%) of these horses (20 of 26 with subchondral lucency as a solitary lesion) racing at a level of competition equal to or better than the pre-injury level. Of the 14 horses which were not operated, 6 (42%) returned to racing of which only 2 (14%) raced at the same pre-injury level of competition. Radiographic evidence of radial or intermediate carpal bone subchondral lucency is an indication of cartilage and bone damage which is best treated with arthroscopic surgery.

Large colon resection for treatment of lymphosarcoma in two horses.

With the exception of lipoma, neoplasia of the gastrointestinal tract is rare in horses. Lymphosarcoma is the most common neoplasm of the hematopoietic system in horses. In horses with lymphosarcoma of the large colon, clinical signs may include intermittent signs of mild abdominal pain, weight loss, pyrexia, and pelvic flexure impaction caused by impingement of the colonic lumen by the mass. Peritoneal fluid analysis may be normal or have a high total protein concentration. If signs of metastasis are not evident, resection of the large colon affected by the mass may prolong survival.

Microvascular permeability and endothelial cell morphology associated with low-flow ischemia/reperfusion injury in the equine jejunum.

Microvascular permeability of the jejunum of clinically normal equids and microvascular permeability associated with 60 minutes of ischemia (25% baseline blood flow) and subsequent reperfusion were investigated. Eight adult horses were randomly allotted to 2 equal groups: normal and ischemic/reperfusion injury. Lymphatic flow rates, mesenteric blood flow, and lymph and plasma protein concentrations were determined at 15-minute intervals throughout the study. Microvascular permeability was determined by estimates of the osmotic reflection coefficient, which was determined when the ratio of lymphatic protein to plasma protein concentration reached a constant minimal value as lymph flow rate increased (filtration-independent lymph flow rate), which occurred at venous pressure of 30 mm of Hg. Full-thickness jejunal biopsy specimens were obtained at the beginning and end of each experiment, and were prepared for light microscopy to estimate tissue volume (edema) and for transmission electron microscopy to evaluate capillary endothelial cell morphology. The osmotic reflection coefficient for normal equine jejunum was 0.19 +/- 0.06, and increased significantly (P < or = 0.0001) to 0.48 +/- 0.05 after the ischemia/reperfusion period. Microscopic evaluation revealed a significant increase (P < or = 0.0001) in submucosal and serosal volume and capillary endothelial cell damage in horses that underwent ischemia/reperfusion injury. Results indicate that ischemia/reperfusion of the equine jejunum caused a significant increase in microvascular permeability.

Large colon impaction in horses: 147 cases (1985-1991)

Medical records from all horses with large colon impaction admitted between 1985 and 1991 were examined. Large colon impaction was diagnosed in 147 of 1,100 (13.4%) horses with colic. One hundred thirty horses were admitted for further evaluation of acute onset of abdominal pain after having been examined and treated by referring veterinarians, and 17 horses that were hospitalized for unrelated medical problems developed large colon impaction. Female horses (92/147; 62.6%) were more commonly affected than males. The age ranged from 1 to 29 years (median, 7.1 years). Mean duration of clinical signs of abdominal pain prior to referral was 32 hours. At admittance, signs of abdominal pain were not detectable in 70/147 (48%) horses, and were mild in 50 (34%), moderate in 16 (11%), and severe in 11 (7%). Heart rate ranged from 30 to 86 beats/min (median, 44 beats/min), and most horses had a decrease in gastrointestinal sounds. Transrectal palpation was used to identify the impaction location as being the pelvic flexure in 103 (70.1%) horses, colon on the left side in 30 (20.4%) horses, and colon on the right side in 14 (9.5%) horses. All 147 horses received fluids i.v. and nonsteroidal anti-inflammatory medications or sedatives, including flunixin meglumine (124 horses, 84.3%) xylazine hydrochloride (81, 55%), butorphanol (6, 0.04%), and detomidine hydrochloride (9, 0.04%). Duration of medical treatment required to resolve the impaction ranged from 1 to 6 days (mean, 2 days). In addition to medical treatment, 24 (16.3%) horses also required surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Progression of femoropatellar osteochondrosis in nine young horses. Clinical, radiographic and arthroscopic findings.

The clinical and radiographic progression, and arthroscopic findings for nine young horses (< 1 year of age) with femoropatellar osteochondrosis (OCD) are presented. Horses had a 2 to 12 week history of bilateral (8 horses) or unilateral (1 horse) hindlimb lameness. The most consistent clinical signs included femoropatellar joint distention and bilateral hindlimb lameness. At the onset of clinical signs, radiographic lesions were not present (4 horses) or subtle (5 horses), but were easily identified on radiographs taken 4 to 24 weeks later. Arthroscopic surgery was delayed until radiographic changes became obvious. Surgical findings in 20 femoropatellar joints were most commonly osteochondral "flaps" located on the proximal lateral trochlear ridge of the femur and were larger than had been indicated by the radiographs. Eight horses were being used for their intended purpose, which was racing (3 horses were racing and 3 were in race training), dressage (1 horse) or pleasure riding (1 horse). One horse required a second surgery when similar lesions developed on the opposite stifle, and was euthanatized 2 months later because of persistent lameness. One clinical signs are observed, osteochondrosis lesions of the distal femur can progress in foals younger than 9 months of age and the full extent of the radiographic lesion may take several weeks to develop.

Evaluation of the microcirculation of the equine small intestine after intraluminal distention and subsequent decompression.

Effects of intraluminal distention (25 cm of H2O, 120 minutes) and subsequent decompression (60 minutes) on intramural vascular patterns of the small intestine was evaluated in 7 anesthetized horses. Intraluminal distention (25 cm of H2O, 120 minutes) was created in 2 jejunal segments in each horse. Experimental and control segments were removed either immediately after the experimental period or after 60 minutes of decompression. The vascular system of experimental and control jejunal segments was lavaged with NaCl, then was injected with a blue-colored radiopaque medium for microangiography or with a diluted methyl methacrylate for scanning electron microscopy of microcorrosion vascular casts. After angiographic evaluation, tissue sections were prepared for light microscopic evaluation to assess vascular filling and tissue morphology. The distended segments had short villi, which were separated by expanded crypts, and had mesothelial cell loss, neutrophil infiltration, and edema in the seromuscular layer. The number of perfused vessels was significantly (P < 0.05) decreased in the seromuscular layer and, to a lesser extent, in the mucosal layer of the distended segments, compared with controls. After decompression, the morphologic lesions progressed in mucosal and serosal layers and the number of observed vessels increased in all intramural layers; however, vascular density did not return to the predistention state. These results identify altered intramural vascular patterns in the equine jejunum during luminal distention and subsequent decompression.

Evaluation of the microcirculation of the equine jejunum and ascending colon after ischemia and reperfusion.

Intramural vascular patterns of the jejunum and colon were evaluated during ischemic strangulation obstruction (ISO, 70 minutes) and subsequent reperfusion (60 minutes) in 7 adult anesthetized horses. Microvasculature of experimental and control segments was described by comparison of results from microangiography, light microscopy, and scanning electron microscopy of vascular replicas. Experimental and control segments with isolated vascular arcades were removed either immediately after the experimental period or after 60 minutes of reperfusion. Blood was flushed from the vascular system by use of isotonic NaCl, and the segments were divided. Half of each segment was perfused with a modified radiopaque medium for microangiographic evaluation, and half was perfused with dilute methyl-methacrylate to create a vascular replica to be studied by scanning electron microscopy. Microangiographic section also were evaluated for histologic changes. Microvasculature of jejunal control segments and all colon segments was similar to described normal microvasculature of the equine jejunum and ascending colon. In jejunal ISO segments, intramural perfusion was redistributed away from the mucosa. In the villi, the central arteriole was short and convoluted and the subepithelial capillaries were not filled. The submucosal vessels and crypt capillaries were congested, compared with those of controls, and the serosal vessels were not filled in the ischemic segments. Histologic grade II-III mucosal lesion was seen in jejunal ISO segments. Reperfused jejunal segments had a transmural hyperemic response, and previously unfilled capillaries were observed in all intestinal layers. After reperfusion, the mucosal lesion progressed to grade III-IV and a cellular infiltrate and edema formation were observed in the serosa. The intramural vasculature of the ischemic and reperfused colon remain unchanged. Minimal histologic damage was observed in the colon after 70 minutes of ISO or after 60 minutes of reperfusion.

Removal of a fracture fragment from the palmar aspect of the intermediate carpal bone in a horse.

A 10-year-old Dutch Warmblood gelding sustained a fracture of the palmar tuberosity of the intermediate carpal bone 2 weeks prior to admission. The dorsolateral-palmaromedial oblique and flexed lateromedial radiographic views revealed the fracture line. The palmar fracture fragment from the intermediate carpal bone was removed by arthrotomy of the palmar intercarpal joint, which was approached through the carpal canal. Twenty months after surgery, the horse was show jumping without evidence of lameness.

Left dorsal displacement of the colon with splenic adhesions in three horses.

Three horses underwent exploratory celiotomy because of signs of acute abdominal pain. At surgery, all horses were diagnosed as having left dorsal displacement of the large colon. Each surgery was complicated by fibrous adhesions of the spleen to the body wall. All horses had previously undergone abdominal surgery for colic. In these cases, it appeared that the left large colon displaced cranially and then entered the renosplenic space from a cranial to caudal direction. Adhesions of the spleen to the body wall would prevent correction of left dorsal displacement of the large colon by the rolling technique.