Development of a laboratory animal model of postoperative small intestinal adhesion formation in the rabbit.

In order to establish a model of postoperative intestinal adhesions that would simulate the problem experienced in horses, New Zealand White rabbits were utilized to compare two models of adhesion formation that had been successful in the horse, an ischemic strangulating obstruction (ISO) model and a serosal scarification model. An untreated control group was compared with animals subjected to 1, 2, 3 and 4 h periods of ISO, and to serosal scarification. At postmortem examination 14 d postoperatively, the number of rabbits in each group with adhesions was recorded. Serosal scarification was significantly more consistent at producing adhesions than ISO (Fisher's exact test, P = 0.0022). The 3 h of ISO group was significantly different from the control group: however, compared to the serosal scarification group, fewer animals had adhesions and one animal died of complications associated with the experimental procedure. Based on these results, serosal scarification was selected as the best model for utilization in further studies of adhesion prevention.

Utilization of the serosal scarification model of postoperative intestinal adhesion formation to investigate potential adhesion-preventing substances in the rabbit.

A rabbit serosal scarification model was utilized to compare the ability of four drugs, previously administered peri-operatively to horses undergoing exploratory celiotomy, to prevent the development of postoperative intestinal adhesions. The substances compared were 32% Dextran 70 (7 mL/kg), 1% sodium carboxymethylcellulose (7 mL/kg), trimethoprim-sulfadiazine (30 mg/kg), and flunixin meglumine (1 mg/kg). The first two were administered intra-abdominally following surgery, while the latter two were administered systemically in the peri-operative period. Fibrous adhesions were evident in all animals in the untreated serosal scarification group. No significant difference in the number of animals with adhesions was found between the untreated control group and any treatment group, nor among the treatment groups. Microscopic examination of adhesions collected at postmortem examination revealed fibers consistent with cotton, surrounded by a giant-cell reaction and ongoing acute inflammation. The source of the fibers was likely the cotton laparotomy sponges used to scarify the intestinal surface, since the pattern in the granuloma and sponge fibers appeared similar under polarized light. Though consistent intestinal adhesion formation was produced in the rabbit, the presence of foreign body granulomas may prevent consideration of this model for future research. The drugs tested were ineffective in preventing the formation of postoperative small intestinal adhesions in this model.

Evaluation of exploratory laparotomy in young horses: 102 cases (1987-1992).

OBJECTIVE: To determine, in a population of young horses, whether a variation exists among neonates, sucklings, weanlings, and yearlings regarding recovery from anesthesia, short- and long-term survival rates, and postoperative adhesion formation following exploratory laparotomy. DESIGN: Retrospective study. ANIMALS: 102 horses < 25 months old that underwent exploratory laparotomy. PROCEDURE: Pre-, intra-, and postoperative information was retrieved from medical records, conversations with referring veterinarians, owners, or trainers, and race records. Survival rates (recovery from anesthesia and short- and long-term survival) were compared with age, lesion type, lesion location, surgical procedure, and development of clinically important postoperative intestinal adhesions. RESULTS: Of the 73 horses that recovered from anesthesia, 69 were available for follow-up. Of the 69 horses, 7 (10%) died of complications associated with formation of intestinal adhesions. Age did not affect incidence of adhesion formation, lesion type, lesion location, or surgical procedure performed. Long-term survival rate after surgery for correction of a small-intestinal lesion was 34%, whereas that after surgery for correction of a large-intestinal lesion was 65%. CLINICAL IMPLICATIONS: Surgical treatment of colic in young horses resulted in survival rates that are similar to those reported for mature horses. The incidence of clinically important postoperative adhesions was greater than that found for young horses in earlier studies. This may be the result of the younger age of our study population. Alternatively, improvements in operative techniques and postoperative management may allow a larger percentage of horses to survive long term and develop complications such as adhesion formation.

Factors affecting incisional complication rates associated with colic surgery in horses: 78 cases (1983-1985).

From May 1, 1983 to April 1, 1985, 142 operations were performed on horses with signs of acute abdominal pain (colic), using a ventral midline incision. Seventy-eight horses lived for at least 15 days after surgery or had acute dehiscence and were included in the study. Seventy horses had surgery once, and 8 horses had surgery 2 or more times. Six-month follow-up evaluation was obtained for 66 horses that had 1 surgery and for 6 horses that had multiple surgeries. Incisional complications included drainage (including infection), acute dehiscence, hernia, and suture sinus formation. The effects of preoperative peritoneal fluid presence, enterotomy or resection, suture material and pattern used in the linea alba, type of skin closure and use of a sutured-on stent bandage on the incidence of incisional complications were investigated. The complication of incisional infection rate associated with a near-far-far-near suture pattern vs simple interrupted pattern in the linea alba was the only statistically significant (P less than 0.05) difference observed.

Congenital malformation of the large colon causing colic in a horse.

An abnormal mesocolic attachment which resulted in a stellate malformation of the left colon adjacent to the pelvic flexure was suspected to be the cause of intermittent episodes of colic in a horse. Resection and side-to-side anastomosis of the large colon at the level of the sternal and diaphragmatic flexures was performed and the horse made an uneventful recovery from surgery. Only minor serum biochemical changes were observed in the initial postoperative period. The abnormal mesocolic attachment was probably a congenital anomaly.

Severe Synovitis in Two Horses due to the Use of Irrigating Solutions Containing Methanol and Formaldehyde.

Two horses were examined because of chronic lameness, which followed arthroscopy in one case, and tendon sheath lavage in a second case. Clinical investigations linked both cases to the use of irrigating fluids containing preservatives. The clinical signs were reproduced in a Shetland pony by injection and lavage of the carpal joints with the same fluid. Lameness was slow in onset and accompanied by profound periarticular fibrosis. Postmortem examination confirmed the presence of a severe, erosive, noninfectious arthritis that may have an immune-mediated component. Clinicians should read product labels carefully and be aware of the dangers of exposing synovial tissues to solutions containing preservatives.

Immune-mediated hemolytic anemia associated with trimethoprim-sulphamethoxazole administration in a horse.

A 10-year-old, thoroughbred gelding was administered sulphonamide drugs during surgical treatment of guttural pouch mycosis. The horse became anemic and a diagnosis of immune-mediated hemolytic anemia was made after other causes of anemia had been ruled out. The anemia resolved after the drugs were withdrawn.

An abnormal digital flexor tendon sheath in the metacarpal region in a horse.

An abnormal digital flexor tendon sheath was present in the mid to lower metacarpal region in a horse. Positive contrast radiography showed that it communicated with the carpal synovial sheath but not with the digital synovial sheath. Cytological and physical analysis of fluid from the abnormal tendon sheath revealed that it was compatible with normal synovial fluid. This abnormal tendon sheath was probably a congenital anomaly.

Extension large colon resection in 12 horses.

Extensive resection (50-75%) of the large colon was performed in 12 horses. Indications for resection were: loss of viability due to large colon volvulus (seven), thromboembolic episode (three), impairment of flow of ingesta due to adhesions (one), or congenital abnormalities (one). The time required to correct the primary cause of abdominal pain and complete the resection ranged from 2.5 to 4.75 hours. Three horses had severe musculoskeletal problems postoperatively and were euthanized in the recovery stall. Four other horses were euthanized early in the postoperative period because of: further large colon infarction (two), ileus (one), or small intestinal problems (one). Five horses survived with no apparent nutritional or metabolic problems during two to three weeks of hospitalization. Clinical data were obtained from these horses from nine months to eighteen months postoperatively and revealed no clinical or clinicopathological abnormalities in four of them; the fifth horse exhibited diarrhea and weight loss four months postoperatively but responded to diet change.

Multiple aneurysmal bone cysts in a foal.

Multiple aneurysmal bone cysts (ABCs) are previously unreported in horses. An ABC was diagnosed in the left 3rd metacarpal of a Thoroughbred foal, which partially resolved following surgical curettage. A 2nd ABC developed in the left tibia, 7 wk postoperatively, and the foal was euthanized.

Equine Colic: Seventy-six Cases Resulting from Incarceration of the Large Colon by the Suspensory Ligament of the Spleen.

Incarceration of the large colon by the suspensory ligament of the spleen was diagnosed and surgically corrected on exploratory celiotomy in 76 horses exhibiting abdominal pain. The condition was diagnosed most frequently during the winter months in mature males of mean age 4.7 years. Clinical signs progressed slowly and included mild to moderate abdominal pain and distension with moderate tachycardia. The mean duration of colic prior to surgical intervention was 20.7 hours. The mild nature of the colic, the findings on palpation per rectum, and the continued passage of feces in 40% of horses, frequently led to the diagnosis and treatment of colonic impaction prior to admission. The condition was correctly diagnosed prior to exploratory celiotomy, by palpation per rectum, in only 18% of cases. Two types of displacement were identified. Sixty-six (86.8%) animals survived and were discharged from the hospital; the longterm survival rate was 78.9%.

Invasive teat surgery in dairy cattle: part I - surgical procedures and classification of lesions.

A prospective study was performed to identify the nature and management of teat abnormalities in cows presented to a referral teaching hospital during a three year period. All cattle (n = 60) admitted to the Ontario Veterinary College for teat problems were evaluated by physical examination; in 53 teats, contrast radiography or xeroradiography were obtained. Surgery was performed on 52 teats from 51 cows and a prosthesis was implanted in 27 teats. Short term (under two weeks) complications included intraoperative bleeding (n = 6), milk leakage through the incision (n = 4), and failure to milk by machine in 26 cases. Histopathological diagnosis of sections taken from obstructive lesions included fibrous tissue (n = 8), normal mammary tissue (n = 3), fibropapilloma, mammary polyps, and inflamed mucosa (one each). The lesion could be classified into five types: 1) focal teat cistern obstruction, 2) diffuse teat cistern obstruction, 3) membranous obstruction, 4) diffuse teat and gland cistern obstruction, or 5) leakage of milk through an abnormal route (i.e. teat fistula, webbed teat, or lacerations).

Invasive Teat Surgery in Dairy Cattle: II - Long-term Follow-up and complications.

A prospective study was performed on 52 teats that were operated upon at the Ontario Veterinary College over a three year period for various problems. Long-term postsurgical follow-ups were obtained to assess milking ability. Sixty-three percent of all the cows that had surgery were classified by the Canadian Holstein Association as "good" or better. The implantation of a prosthesis was required in 32 teats and was found to be associated with: a higher prevalence of chronic mastitis, a lower long-term milking success rate, and an increased prevalence of abnormal milking times. Of the five types of teat lesions encountered, Type I (<30% of teat cistern involved) and Type V (lacerations, webbed teats, fistulae) had the best short and long-term prognosis for lactation. Overall, 60% of the operated teats were milking one month after surgery, and 41% at the end of the lactation.

Postcastration eventration in 18 horses: the prognostic indicators for long-term survival (1985-1995).

Castration of horses is considered a common and routine surgical procedure, but the potential for complications is high. By far the most serious of these is eventration. The objectives of this study were to determine the long-term survival of horses undergoing surgical treatment of indirect (1) inguinal eventration of the small intestine following castration, and to identify prognostic indicators for survival. The case records of 18 horses undergoing surgical treatment of postcastration eventration (PCE) between 1985 and 1995 were reviewed. Follow-up information was obtained by telephone interviews 2 to 13 y postoperatively. A Cox proportional hazard regression model was fitted to determine which clinical features were of significant influence to survival. Clinical features with a significant negative influence on survival were an inguinal surgical approach for correction, an increased length of prolapsed bowel, and performance of bowel resection and anastomosis. Significant postoperative complications developed in 89% of cases; 44% of cases in the "inguinal" surgical approach group developed peritonitis, compared with 10% in the "midline" approach group. Of all horses in this study, 72% were discharged from the hospital; however, only 40% of horses in the inguinal approach group were discharged. The long term survival rate (> 1 y) for all horses in this study was 44%, with a median survival time of 3-1/2 mo.

Colonic atresia in cattle: A prospective study of 43 cases.

This prospective study was initiated to document the success rate obtained in the treatment of colonic atresia in calves, identify factors that influence survival rate, and to report the histopathological appearance of the proximal blind end of the ascending colon. Forty-three calves with intestinal obstruction due to colonic atresia were admitted to the Ontario Veterinary College between September 1982 and May 1986. Parameters recorded prospectively in this study included age, breed, sex, history, vital signs, acid-base and electrolyte status, location of intestinal atresia, medical and surgical management, and outcome. The typical history and clinical signs included failure to pass meconium or feces, decreased appetite, and progressive depression and abdominal distension. The most common site of colonic atresia was the midportion of the spiral loop of the ascending colon (n = 25). Of the 43 calves, three (7%) were euthanized at surgery, 21 (49%) died in the hospital, and 19 (44%) survived and were discharged from the hospital. Four of the surviving calves died subsequent to discharge giving an overall long-term (mean 15.9 months) survival rate of 35%. No significant risk factors were identified, although experienced surgeons showed a trend towards increased survival rate.