Long-term survival of equine surgical colic cases. Part 2: modelling postoperative survival

Colic surgery is a frequently performed operation with high postoperative mortality. This study was undertaken to identify variables associated with decreased postoperative survival. We used data from 321 horse years of postoperative survival time to model the probability of survival following recovery from colic surgery. Continuous variables were modelled using a 6 variable, penalised Cox regression model. This demonstrated approximately linear relationships between survival and the following variables: increase in packed cell volume (PCV), intestinal resection length, time to surgery (interval between onset of colic and surgery) and duration of surgery. No significant decrease in survival was demonstrated with increasing age of the patient or with heart rate. The only categorical variable to be significantly associated with decreased survival was epiploic foramen entrapment. The final, fixed effects Cox proportional hazards model of postoperative survival included the variables epiploic foramen entrapment, PCV, resection length and duration of surgery, each variable adjusted for the nonlinear relationship with time to surgery. Residual variation in postoperative survival attributable to professional personnel (referring veterinary surgeon, anaesthetist and surgeon) was explored by fitting each as a random effects term in the model. Little of the residual variation could be attributed to any category of personnel. Model diagnostics indicated little influence by individual outliers on model parameters and little evidence of subjects poorly predicted by the final model. The study highlights factors influencing the long-term survival of horses recovering from colic surgery and proposes a model that can be used to inform prognosis.     

Equine surgical colic: risk factors for postoperative complications

The reason for undertaking this study was that postoperative complications of colic surgery lead to patient discomfort, prolonged hospitalisation and increased cost. Potential risk factors for the 6 most common postoperative complications (jugular thrombosis, ileus, re-laparotomy, wound suppuration, incisional herniation and colic) were evaluated using multivariable models. Jugular thrombosis was associated significantly with heart rate greater than 60 beats/min and with increased packed cell volume (PCV) at admission. The risk of postoperative ileus also increased with increasing PCV at admission and was higher in horses recovering from pedunculated lipoma obstruction. Incisional herniation was strongly associated with wound suppuration and with increasing heart rate at admission. The emergence of cardiovascular parameters as risk factors for several postoperative complications is consistent with the hypothesis that endotoxaemia is important in the development of these complications. Early referral of colic cases, prior to the development of severe endotoxaemic shock, may minimise the risk of some postoperative complications. Horses that have suffered epiploic foramen entrapment, are more than 4 times as likely to undergo re-laparotomy than other horses. Horses that have suffered postoperative ileus have a similarly increased risk of undergoing re-laparotomy. The risk of postoperative colic is significantly associated with horses recovering from large colon torsion (>360 degrees) and with having undergone re-laparotomy. Hazard ratios (with 95% confidence intervals) for these last two effects are 3.1 (1.7, 5.7) and 3.4 (1.9, 6.2), respectively. Knowledge of the risk factors for postoperative complications allows more accurate prognostication postoperatively and suggests ways in which the risk of postoperative complications can be minimised.     

Incarceration of the Small Intestine in the Epiploic Foramen Report of 19 Cases (1983–1992)

The medical records of 19 horses referred for colic and subsequently found (18 confirmed, 1 suspected) to have small intestinal incarceration through the epiploic foramen were reviewed. These horses were of various ages and breeds; they had clinical signs of colic for an average duration of 13.5 hours before examination. Seventeen horses had nasogastric reflux, and 15 had palpable small intestinal distention. Three horses were killed during surgery because of severe intestinal damage. Of the remaining 16 horses, 13 required intestinal resection and anastomosis. The length of incarcerated small intestine varied from 8 cm to 17.6 m. The ileum was involved in 12 cases. In one horse, the mesoduodenum was disrupted before surgery, causing intra-abdominal bleeding; incarceration of bowel was not found during surgery. The short-term (1 month) survival rate was 74% (14 of 19 cases), and the long-term survival rate was 63% (12 of 19 cases). The follow-up period was 3 months to 45 months (mean 17.2 ± 7.2 months).     

Correlation of epiploic foramen length to height,weight, breed,gender and age in horses

Epiploic foramen entrapment (EFE) is one of the most common causes of small intestinal strangulation in horses. Cribbing and previous episodes of colic are suggested as risk factors for its occurrence. The aim of this study was to correlate the height, weight, breed, gender and age to the epiploic foramen (EF) length. Forty-three horses were submitted to post-mortem measurement of epiploic foramen with abdominal and thoracic organs positioned in situ. After data collection, linear regression between EF length and the explanatory variables was performed. None of the post-mortem physical variables was associated with EF length, supporting the hypothesis that there is no association between EF length and age, and that increased intra-abdominal pressure is the most important factor predisposing to EFE recurrence.     

Entrapment of the small intestine in the epiploic foramen in horses: a retrospective analysis of 71 cases recorded between 1991 and 2001

The clinical features of 71 cases in 70 horses in which part of the small intestine became entrapped in the epiploic foramen are described. The horses' sex, age and breed, the month during which they were affected, and whether they exhibited stereotypic behaviour were compared with the same variables in 1279 horses which suffered other types of surgical colic during the same period. Thoroughbred and thoroughbred cross horses were over-represented among the 70 affected horses. There was no age or sex predilection. Fifty-five (77.5 per cent) of the cases occurred between October and March and 15 (21.1 per cent) occurred in January. The cases were significantly more likely to have a history of crib-biting/windsucking than the control group (odds ratio 7.9, 95 per cent confidence interval 4.1 to 15.3). The condition had recurred in two of the horses. Fifty-eight (81.7 per cent) recovered from surgery and 49 (69 per cent) survived until they were discharged from hospital. The median survival time of 31 of the affected horses discharged from the hospital was 700 days, whereas 417 horses with other types of surgical colic had a median survival time in excess of 1931 days.     

A cross-sectional study of colic in horses on thoroughbred training premises in the British Isles in 1997

The aim of this study was to estimate the incidence of colic in horses in Thoroughbred training premises in 1997 in the British Isles. The seasonal pattern and outcome of colic episodes were also investigated, together with any association between premises level variables and colic. Data were collected by a postal questionnaire. The results showed a colic incidence density of 7.19/100 horse years (s.e. 0.42) and a cumulative incidence of colic of 5.80% (s.e. 0.30). Premises were grouped according to whether they had more Flat than National Hunt horses (Flat premises) or more National Hunt than Flat horses (NH premises). A similar rate of colic episodes was found in each group. However, significantly higher cumulative incidences of one episode of colic were found in the Flat premises and of multiple episodes in the NH premises, respectively. The outcome of each episode of colic showed spontaneous recovery in 28.7%, medical recovery in 63.1%, surgical recovery in 2.0% and death in 6.2% of cases. This indicated an overall mortality rate from colic of 0.45 deaths/100 horse years. The seasonal pattern of episodes of colic showed a spring and autumn peak, with significant differences in the seasonal pattern between the Flat and NH premises. Relative risk analysis and logistic regression modelling with random effects showed significant associations between the number of episodes of colic and the number of horses on the premises (allowing for the number of horses on each premises, the larger premises had a decreased risk of colic). After adjusting for the number of horses, 3 other variables were associated with colic; Flat premises (with an increased risk), the owner being the sole person looking after the horses (a decreased risk) and the premises being a combined training and breeding establishment (a decreased risk).     

Pulmonary gas exchange and plasma lactate in horses with gastrointestinal disease undergoing emergency exploratory laparotomy: a comparison with an elective surgery horse population

Objective: To characterize pulmonary gas exchange and arterial lactate in horses with gastrointestinal disease undergoing anesthesia, compared with elective surgical horses, and to correlate these variables with postoperative complications and mortality. Study Design: Prospective clinical study. Animals: Horses undergoing emergency laparotomy for acute intestinal disease (n=50) and healthy horses undergoing elective surgery in dorsal recumbency (n=20). Methods: Arterial blood gas analysis was performed at predetermined intervals on horses undergoing a standardized anesthetic protocol. Alveolar–arterial oxygen gradient was calculated. Predictive factors for postoperative complications and death in colic horses were determined. Results: Arterial oxygen tension (P_aO₂) varied widely among horses in both groups. P_aO₂ significantly increased in the colic group after exteriorization of the ascending colon. P_aO₂ and alveolar–arterial oxygen gradient were not significantly different between groups, and neither were correlated with horse outcome. Arterial lactate in recovery ≥5 mmol/L was associated with a 2.25 times greater relative risk of complications and lactate ≥7 mmol/L was associated with a 10.5 times higher relative risk of death. Conclusion: Colic horses in this population were not more likely to be hypoxemic than elective horses, nor was gas exchange impaired to a greater degree in colic horses relative to controls. Arterial lactate sampled immediately after anesthetic recovery was predictive for postoperative complications and death.     

The effect of inotropic and/or vasopressor support on postoperative survival following equine colic surgery

OBJECTIVE: To determine the effects of dobutamine and phenylephrine on intra- and postoperative survival in horses undergoing emergency abdominal surgery. STUDY DESIGN: Retrospective case analysis. ANIMALS: A total of 637 client-owned horses undergoing colic surgery. METHODS: Clinical details of horses admitted for colic surgery were recorded on a computer database. Information collected included history, clinical variables observed before surgery, anaesthesia and surgical details, and postoperative survival and morbidity rates. Details of specific importance for this study were those recorded during anaesthesia, in particular the duration of dobutamine and phenylephrine administration, separately and combined, and total anaesthesia time. Two outcomes were considered: 1) intra-operative death, i.e. death between time of pre-anaesthetic medication and recovery from anaesthesia (defined as horse walking from recovery box); and 2) all deaths, i.e. death at any time after induction of anaesthesia. The definition of 'death' included euthanasia. Univariable and multivariable statistical analyses were performed to evaluate the associations between dobutamine and/or phenylephrine use and these two outcomes. RESULTS: Results from univariable analyses suggested that dobutamine administration was not significantly associated with increased intra- or postoperative mortality. Phenylephrine administration showed univariable association with intra- and postoperative death. However, in multivariable models adjusted for the effects of heart rate and packed cell volume at admission, the phenylephrine effect was not significantly associated with intra-operative, or other types of death. CONCLUSION: This study provides no evidence to suggest that dobutamine or phenylephrine administration is associated with altered survival rates during or after colic surgery. CLINICAL RELEVANCE: Our study supports previous work, suggesting that pre-existing cardiovascular status is an important prognostic determinant in equine colic cases. It provides no evidence that dobutamine or phenylephrine administration is associated with survival.     

Analysis of Sodium Carboxymethylcellulose Administration and Related Factors Associated with Postoperative Colic and Survival in Horses with Small Intestinal Disease

Objective— To analyze the effect of the intraoperative use of sodium carboxymethylcellulose (CBMC) and related perioperative factors on postoperative colic and survival in horses that had abdominal surgery for colic.
Study Design— Retrospective study.
Animals— Horses (n=203) that had surgery for small intestinal disease; 33 horses had intraoperative administration of CBMC.
Methods— Information was obtained from medical records for 170 horses that had surgery for colic before use of CBMC and 33 horses that had intraoperative CBMC. Kaplan–Meier survival curves were used to estimate median survival time and a Cox proportional hazards model was used to estimate the hazard ratio for the effect of CBMC and other perioperative variables on survival.
Results— Seventy-five percent of horses administered CBMC survived to 180 days, whereas 75% of untreated horses survived 8 days (median survival time=18 days). Horses not administered CBMC were twice as likely to die compared with horses administered CBMC. Horses that had postoperative ileus (POI) were 1.4 times more likely to die than horses without ileus. Similarly, horses with signs of colic after surgery were 1.3 times more likely to die than horses without postoperative signs of colic.
Conclusions— CBMC administration is seemingly protective against death and prolongs survival when used intraoperatively in horses with small intestine disease, particularly horses with postoperative colic or POI. Both POI and colic increased risk of death after surgery.
Clinical Relevance— Intraoperative administration of CBMC in horses that have surgery for small intestinal disease may improve survival, possibly by reducing early adhesion formation.     

Survival and Complications After Large Colon Resection and End‐to‐End Anastomosis for Strangulating Large Colon Volvulus in Seventy‐Three Horses

Objective— To report complications and survival after large colon resection and end‐to‐end anastomosis in horses with strangulating large colon volvulus. Study Design— Retrospective case series. Animals— Horses (n=73) with strangulating large colon volvulus. Methods— Records (January 1995 to December 2005) of horses that had large colon resection and anastomosis for strangulating large colon volvulus were reviewed for complications. Follow‐up data were obtained by telephone questionnaire at least 1 year postoperatively. Cox proportional hazards model was used for multivariate association with survival time. Variables included admission date, age, temperature, heart rate, packed cell volume, total plasma protein concentration, white blood cell count, breed, and sex. Significance was set at P<.05. Results— The most common postoperative complication was diarrhea. None of the 9 variables of interest were significant for survival. Short‐term survival rate (to discharge) was 74%. Overall survival rates at 1, 2, and 3 years postoperatively were 67.8%, 66.0%, and 63.5%, respectively. Four horses died of colic in the first year after surgery. All horses surviving long‐term (>1 year) returned to their intended use (37 brood mares, 2 racehorses, and 1 show horse) with no chronic problems related to the surgical procedure. Conclusion— None of the variables examined were associated with survival. Outcomes were similar to other large studies of surgical colic in the horse. Self‐limiting diarrhea is common after large colon resection and the prognosis for survival after hospital discharge is favorable. Clinical Relevance— Horses that survive the early postoperative period and are discharged after large colon resection and anastomosis have a good chance for long‐term survival with minimal negative impact on quality of life and use.     

Clinical comparison between a continuous Lembert pattern wrapped in a carboxymethylcellulose and hyaluronate membrane with an interrupted Lembert pattern for one-layer jejunojejunostomy in horses

Reasons for performing study: Although experimental studies have demonstrated differences in performance between methods for handsewn jejunojejunostomy in horses, information on clinical results after different methods of anastomosis are rare. Hypothesis: A continuous Lembert pattern wrapped in a carboxymethylcellulose and hyaluronate membrane would perform better than an interrupted Lembert pattern for jejunojejunostomy in horses. Methods: Data was reviewed on 32 horses that underwent jejunojejunostomy from 1993–2002. Kaplan‐Meier analyses and rates for post operative colic and death were used to compare outcomes after an interrupted Lembert pattern (15 horses with strangulating lesions and 5 horses with nonstrangulating lesions) and a continuous Lembert pattern with membrane (12 horses with strangulating diseases). Results: None of the 32 horses had post operative ileus or post operative endotoxaemia. One horse with a continuous pattern required a repeat celiotomy for anastomotic impaction. Short‐term survivals for the interrupted Lembert were 100% (nonstrangulating lesions) and 93% (strangulating lesions) and for the continuous pattern 92% (all strangulating). Long‐term rates for mortality and colic episodes were less for the continuous Lembert pattern with membrane compared with the interrupted Lembert for strangulating lesions (P<0.05) and were less for strangulating lesions than for nonstrangulating lesions (P<0.05). For strangulating lesions, Kaplan‐Meier analyses yielded a survival probability of 70% for up to 9 years after the interrupted Lembert pattern and 80% for up to 5 years for the continuous Lembert pattern. Conclusions and relevance: Both Lembert patterns performed well in clinical use, although the continuous pattern with the carboxymethylcellulose and hyaluronate membrane had superior long‐term outcomes with less colic and mortality from colic.     

Survival rates and post-operative complications after equine colic surgery

SUMMARY A retrospective analysis of 74 cases that underwent surgery for colic was undertaken to determine short and long term survival rates and the incidence of postoperative complications. In 28 cases colic was related to small intestinal lesions and in 46 cases to large intestinal lesions. Pre-operative packed cell volume and heart rate were found to be inversely related to short-term survival. Twenty-five horses (34%) recovered from surgery and were discharged. Of 18 of these cases with available histories, 6 subsequently had one or more episodes of colic since surgery of which 5 eventually died or were euthanased due to further colic; the remaining 12 have remained free from recurrence of colic for longer than 6 months.     

Factors affecting long-term survival of horses recovering from surgery of the small intestine

REASONS FOR PERFORMING STUDY: Epiploic foramen entrapment (EFE) has been associated with a particularly poor post operative prognosis for equine colic cases, but the reasons for this are unknown. OBJECTIVES: To identify variables associated with post operative survival following surgery for small intestinal disease; develop a model describing long-term post operative survival; and identify reasons for the poor prognosis associated with EFE. METHODS: Data from 382 horses undergoing surgery were used to identify variables associated with survival. A multivariable Cox proportional hazards model for post operative survival was developed and model fit evaluated. RESULTS: The final model included the variables total plasma protein (TP) and packed cell volume (PCV) at admission, duration of surgery and the dichotomous variable relaparotomy (yes/no). Risk of death was positively associated with increasing PCV, but negatively associated with increasing TP (which decreased the probability of death). In a univariable model, EFE cases had a significantly higher death rate than other types of small intestinal disease (hazard ratio = 1.7, P = 0.035). Multivariable modelling indicated that some of the increased risk associated with EFE cases was due to lower TP values and longer duration of surgery. CONCLUSIONS: Preoperative TP is associated negatively with the risk of post operative death in horses recovering from small intestinal surgery. Other variables associated with the probability of survival are preoperative PCV, duration of surgery and relaparotomy. The increased post operative death rate of EFE cases can be explained in part by lower TP and longer surgery times of these cases. POTENTIAL RELEVANCE: Total plasma protein may be not simply a measure of hydration status in small intestinal colic cases, but an important determinant of survival. Further investigation of this relationship is warranted. Our model for post operative survival highlights the importance of preoperative TP, PCV and duration of surgery as prognostic indicators. This information should allow a more accurate post operative prognosis following small intestinal surgery.     

Outcome and long‐term follow‐up of 20 horses undergoing surgery for caecal impaction: A retrospective study (2000–2008)

Reasons for performing study: If untreated, caecal impaction may progress to rupture of the caecum and reports of long‐term outcome for horses undergoing surgery for caecal impaction are required. Objectives: To describe short‐ and long‐term complication rates for horses undergoing surgery for caecal impaction in an otherwise life‐threatening gastrointestinal condition. Methods: Case records were reviewed for horses undergoing surgery for caecal impaction. Horses were included in the study if an abnormally large, fluid‐distended or feed‐impacted caecum was the primary diagnosis at surgery and excluded if the caecum had already ruptured upon opening the abdomen, necessitating euthanasia. Short‐term follow‐up data were obtained from clinical records; and included complications, repeat celiotomy and survival to discharge. Long‐term survival was defined as survival for >1 year post operatively. Long‐term follow‐up data were obtained through telephone interviews with owners and referring veterinary surgeons. Survival, occurrence of post operative colic and subsequent use of the horse were recorded. Results: Twenty horses underwent surgery for caecal impaction: 16 horses underwent caecal bypass (typhlotomy and removal of caecal contents, ileal transection followed by ileocolostomy); 3 underwent typhlotomy alone; and one horse underwent typhlotomy followed by a second procedure where caecal bypass was performed. Five horses (25%) were admitted for colic evaluation with primary caecal impactions, in 10/20 (50%) of cases the impaction was secondary to previous orthopaedic surgery and in 5/20 (25%) caecal impaction was identified at repeat celiotomy following a previous colic surgery. Sixty‐five percent (13/20) of horses survived to discharge; 11/13 (85%) of horses discharged survived long term; 100% (3/3) horses that received typhlotomy alone were discharged and survived long term. Conclusions: The prognosis following caecal impaction surgery is fair, if the horse survives to discharge then prognosis for long‐term survival is good. Potential relevance: Surgery for caecal impaction carries a fair prognosis for a potentially life threatening disease, in particular where caecal dysfunction is suspected.     

Prevalence and risk factors associated with outcome of surgical removal of pedunculated lipomas in horses: 102 cases (1987-2002)

OBJECTIVE: To determine the prevalence of pedunculated lipomas and identify risk factors affecting postoperative complications and survival in horses at a veterinary teaching hospital undergoing surgery for colic caused by pedunculated lipomas. DESIGN: Retrospective study. ANIMALS: 102 horses with a diagnosis of pedunculated lipoma. PROCEDURE: Age, breed, weight, and sex of horses with pedunculated lipomas were compared with the total equine hospital population and the population of horses admitted for abdominal surgery during the same period. Follow-up information was obtained by reevaluation or contact with owners via telephone or written request. RESULTS: Prevalence of pedunculated lipomas as a reason for abdominal surgery in horses, compared with the population of horses with and without lipomas admitted for abdominal surgery, was 10%. Castrated male Saddlebred and Arabian horses > 14 years old were identified as being at risk for developing pedunculated lipomas. Postoperative complications were detected in 72% of horses with pedunculated lipomas. Variables associated with low survival rates included surgery before 1992, heart rate > 80 beats/min, abnormal color of abdominal fluid, pale mucous membranes, surgery requiring intestinal resection, and inability to attain a mean arterial pressure > or = 100 mm Hg. Horses undergoing surgery from 1992 to 1996, weighing < 409 kg (900 lb), or requiring jejunojejunal anastomosis had a high survival rate. CONCLUSIONS AND CLINICAL RELEVANCE: Although many of the variables reflected the health of the horse at the time of surgery, results may help veterinarians recognize risk factors associated with development of pedunculated lipomas and better predict the outcome of horses undergoing surgery for colic caused by pedunculated lipomas.     

Partial Equine Lung Resection Using a Stapling Instrument

Four horses (aged 1 to 18 years) with no apparent respiratory or cardiovascular abnormalities underwent thoracotomy and partial resection of a cranial lung lobe. A stapling instrument was used. Pulmonary function testing prior to and 30 days following surgery showed no significant change in inspiratory or expiratory resistance, compliance, or work of breathing. Postoperative complications consisted of a mild pneumothorax in all horses and localized incisional infection in two horses. All horses displayed a temporary decrease in forward motion of the forelimb on the operated side. Postmortem examination was performed 30 days after surgery; pleural thickening and adhesions between the lung and thoracotomy site were found. The excisionai margin of each cranial lobe was straight with slight puckering due to multiple surgical wire staples. Adjacent tissue collapse and compression were confined to an area no greater than 1 cm from the staples. Beyond this compression, the remaining lung at the surgical site was histologically normal. Subsequently, one horse suffering from recurrent episodes of clinical signs attributed to pleuropneumonia underwent left thoracotomy and partial lung resection followed by a right thoracotomy 48 days later. The horse's condition improved postoperatively, and he was able to undergo normal conditioning and racing.     

Are horses that undergo an exploratory laparotomy for correction of a right dorsal displacement of the large colon predisposed to post operative colic,compared to other forms of large colon displacement?

Reason for performing study: It is a clinical impression that horses diagnosed with a right dorsal displacement (RDD) of the large colon, are more likely to suffer from recurrent episodes of colic post operatively, compared to other forms of nonstrangulating large colon displacement. Objectives: To investigate whether the type of nonstrangulating large colon displacement identified at exploratory laparotomy would influence long‐term outcome. Hypothesis: Horses identified with a RDD of the large colon at exploratory laparotomy would be more likely to experience recurrent episodes of post operative colic than other types of displacement. Materials and methods: Medical records for horses undergoing an exploratory laparotomy, from 2000–2008, for a nonstrangulating large colon displacement were reviewed. Data retrieved included: subject details, previous medical history, details of current episodes of colic, results of preoperative examination, surgical findings and procedures, post operative management and complications. Follow‐up information was obtained by reference to computerised clinical records and by telephone questionnaire administered to the horse's owner or carer, and included details of any colic episodes exhibited by the horse after discharge and whether a repeat celiotomy had been required to resolve the colic episodes. Results: There were 165 surgeries identified, in 154 horses. It was found that those horses with RDD were significantly more likely to experience recurrent episodes of colic requiring veterinary intervention post operatively compared to other types of displacement. Clinical relevance: Long‐term prognosis and likelihood of post operative complications is an important consideration for both owners and veterinarians.     

Retrospective study of the risk factors and prevalence of colic in horses after orthopaedic surgery

The records of 496 orthopaedic operations on 428 horses were reviewed to estimate the prevalence of, and identify the risk factors for, the development of colic in horses after surgery. Colic was defined as any recognised sign of abdominal pain that could not be attributed to a concurrent disease. Fourteen of the horses developed colic; eight of them were undiagnosed, three were classified as impactions, one as tympanic colic of the colon, one as incarceration of the small intestine in the epiploic foramen, and one as left dorsal displacement of the colon in the nephrosplenic space. Morphine was associated with a four-fold increased risk of colic compared with the use of no opioid or butorphanol, and out-of-hours surgery was also associated with an increased risk.     

Hypoglycemia and hepatic ischemic necrosis after small intestinal incarceration through the epiploic foramen in a horse.

A 16-year-old stallion was presented to the Louisiana State University Veterinary Teaching Hospital for evaluation of acute abdominal pain. Physical examination and diagnostic procedures indicated a strangulating obstruction of the small intestine. At exploratory celiotomy, a strangulating incarceration of the jejunum through the epiploic foramen was found. The incarcerated small intestine was reduced, then resection of the nonviable bowel and anastomosis performed. After surgery, the horse exhibited clinical signs and laboratory findings associated with hypoglycemia and died in spite of emergency treatment. On post-mortem examination, a large thrombus was present in the portal vein at the level of the epiploic foramen and the liver had multiple large infarcted areas. The post-operative signs of hypoglycemia and necropsy findings of widespread hepatic ischemic necrosis are complications of epiploic foramen incarceration of the small intestine not previously reported and may in part explain the high mortality rate described for this lesion.     

Modelling long-term survival of horses following surgery for large intestinal disease

REASONS FOR PERFORMING STUDY: Large intestinal diseases are an important cause of equine colic that require surgical management, but there is little published information about long-term survival of such cases. OBJECTIVES: To identify variables associated with post operative mortality and to develop a model for post operative survival following surgery for large intestinal disease. METHODS: Clinical data and long-term follow-up information from 275 horses undergoing surgery for large intestinal disease were used. A multivariable, Cox proportional hazards model for post operative death was developed and the fit of the model evaluated. RESULTS: The continuous variables age, heart rate and packed cell volume (PCV) were associated positively with the risk of post operative death, as were the categorical variables resection (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.2-5.1) and relaparotomy (OR 3.5, 95% CI 1.4-8.4). CONCLUSIONS: In the population studied, the probability of post operative survival following surgery for large intestinal disease was associated with the cardiovascular parameters heart rate and PCV on admission, age of the horse and whether it underwent resection or relaparotomy. POTENTIAL RELEVANCE: The prognosis for post operative survival for horses with large intestinal disease may be improved by early surgery, prior to the development of cardiovascular compromise. Surgeons should be aware that increasing age, resection of large colon and relaparotomy are all associated with a worsening prognosis for survival.