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.     

Risk Factors for Equine Postoperative Ileus and Effectiveness of Prophylactic Lidocaine

Background: Postoperative ileus (POI) is a frequent and often fatal complication of colic surgery. Reliably effective treatments are not available.
Objectives: To determine risk factors and protective factors associated with POI, and to assess the effect of lidocaine IV on short-term survival.
Animals: One hundred and twenty-six horses that underwent small intestinal colic surgery and that survived for at least 24 hours postoperatively.
Methods: Retrospective cross-sectional study. The association of 31 pre-, intra-, and postoperative variables with POI and the association of lidocaine treatment with short-term survival were investigated. Associations were evaluated with univariable logistic regression models, followed by multivariable analysis.
Results: Significant associations of high heart rate (odds ratio [OR] = 1.05, 95% confidence interval [CI] 1.03–1.08), the presence of more than 8 L of reflux at admission (OR = 3.02, 95% CI 1.13–8.02) and the performance of a small intestinal resection (OR = 2.46, 95% CI 1.15–5.27) with an increased probability of POI were demonstrated. Prophylactic lidocaine treatment was significantly associated with a reduced incidence of POI (OR = 0.25, 95% CI 0.11–0.56). Lidocaine treatment was also significantly associated with enhanced short-term survival (OR = 0.30, 95% CI 0.09–0.98).
Conclusions and Clinical Importance: The variables associated with an increased risk of POI can be useful in identifying horses at risk of POI and in providing a more accurate prognosis. The results are supportive for lidocaine IV as an effective prokinetic treatment after small intestinal colic surgery.     

Risk factors associated with development of postoperative ileus in horses.

OBJECTIVE: To determine risk factors associated with development of postoperative ileus in horses undergoing surgery for colic. DESIGN: Case-control study. ANIMALS: 69 horses that developed ileus after surgery for colic and 307 horses that did not develop postoperative ileus. PROCEDURE: Signalment, history, clinicopathologic data, treatment, lesions, and outcome were obtained from medical records. RESULTS: Variables associated with increased risk of postoperative ileus included age > 10 years, Arabian breed, PCV > or = 45%, high serum concentrations of protein and albumin, anesthesia > 2.5 hours' duration, surgery > 2 hours' duration, resection and anastomosis, and lesions in the small intestine. Enterotomy reduced the risk of postoperative ileus. After multivariate logistic regression, the final model included the variables Arabian breed, PCV > or = 45%, lesion type, duration of surgery (> 2 hours vs < or = 2 hours), and pelvic flexure enterotomy. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that by evaluating certain factors, horses at increased risk of postoperative ileus may be recognized before the condition develops. Preventative treatment and early intervention may be instituted in these horses. Shortening surgery time and performing an enterotomy may decrease the probability of horses developing postoperative ileus.     

Serial venous lactate measurement following gastrointestinal surgery in horses

BackgroundProspective clinical study of blood lactate concentration in horses undergoing colic surgery is needed to determine utility in outcome prediction.ObjectivesTo evaluate venous lactate measurements in horses following colic surgery, including immediately after anesthetic recovery and daily throughout hospitalization, as well as to determine if lactate concentrations were significantly higher in horses that developed postoperative complications or did not survive to hospital discharge.MethodsHorses > 1 year of age undergoing surgery for colic and recovered from general anesthesia were sampled. A portable lactate meter was used to measure venous samples collected immediately following anesthetic recovery and daily throughout hospitalization. Complications arising during hospitalization and survival to hospital discharge were recorded.ResultsFifty one horses were enrolled, ranging in age from 2 to 29 years. Lactate concentration immediately following anesthetic recovery was higher in horses that developed complications during hospitalization (p = 0.046). The odds of developing complications postoperatively were doubled for horses with a venous lactate concentration > 5 mmol/L. Lactate measurements in non-survivors were significantly higher compared to survivors by 96 h postoperatively (p < 0.006).ConclusionsHigher venous lactate concentrations in the postoperative colic period were associated with an increased risk of complications and death. Results suggest horses with higher venous lactate measurements in recovery are more likely to have postoperative complications, with the odds of developing complications doubled for horses with a venous lactate > 5 mmol/L. Evaluation of venous lactate could provide information on prognosis in the postoperative period for horses with surgical colic.     

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.     

Clinical assessment and outcome of a single-layer technique for anastomosis of the small intestine in horses

In order to assess postoperative outcome in horses undergoing end-to-end anastomosis of the small intestine, performed using a one-layer technique, 15 horses that underwent exploratory coeliotomy, resection of the small intestine and end-to-end anastomosis using a continuous Lembert pattern were studied. Information on the age, breed, sex, diagnosis, treatment, complications and outcome of each case were obtained from medical records. Follow-up information was obtained via telephone conversations with clients and trainers. Five of the horses had short-term postoperative complications: one had postoperative ileus (POI), colic and peritonitis, one had POI and colic, two had POI only and one had diarrhoea only. A second exploratory coeliotomy was recommended in two of the 15 horses (13 per cent). The short-term survival rate, defined as survival up to the time of discharge from the hospital, was 93.3 per cent (14 of 15 horses). The long-term survival rate, defined as survival for at least 12 months after the surgery, was 84.6 per cent (11 of 13 horses followed up).     

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.     

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.     

Plasma arginine vasopressin concentration in horses undergoing surgery for colic

Objective – To determine if horses before undergoing anesthesia for surgical correction of colic would have lower plasma arginine vasopressin (AVP) concentrations than healthy horses undergoing anesthesia for arthroscopic surgery, and would not increase their plasma AVP concentrations in response to anesthesia and surgery. Design – Prospective clinical study. Setting – University teaching hospital. Animals – Fourteen horses with colic and 8 healthy horses. Interventions – Horses with colic underwent anesthesia and surgery for alleviation of colic, and healthy horses underwent anesthesia and surgery for arthroscopy. Measurements and Main Results – Plasma AVP was measured perioperatively in horses with colic and in healthy horses. Before anesthesia, and 30 and 60 minutes after induction, horses with colic had greater median plasma AVP concentrations than control horses (P≤0.001); thereafter during anesthesia differences in AVP concentrations between the 2 groups were not significant. In the control group, plasma AVP concentration increased during 120 minutes of anesthesia; no such increase occurred in colic horses. Conclusions – Compared with healthy horses, horses with colic had higher preanesthesia plasma AVP concentrations that did not increase further in response to anesthesia and surgery. Exogenous AVP is associated with decreased splanchnic perfusion in a variety of animal species and, therefore, could be detrimental to horses with colic. Thus, it may be inappropriate to use exogenous AVP in support of blood pressure in anesthetized horses with colic. Further studies are warranted to define appropriate indications for the use of AVP in horses with colic.     

Bacterial Culturing of Ventral Median Celiotomies for Prediction of Postoperative Incisional Complications in Horses

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.     

Risk factors for reduced postoperative fecal output in horses: 37 cases (1997-1998)

OBJECTIVE: To determine prevalence and risk factors for development of ileus of the large intestine after surgery in horses, identified by reduced postoperative fecal output (RPFO). DESIGN: Retrospective study. ANIMALS: 37 horses that developed RPFO after undergoing general anesthesia for reasons unrelated to the gastrointestinal tract. PROCEDURE: Fecal output was obtained from medical records as number of defecations per 24-hour period after surgery; RPFO was defined as < or = 3 defecations per 24-hour period after surgery. The reference population included 48 horses that defecated > or = 4 times during the same period. Demographic, clinical, and surgical variables were evaluated for their association with development of RPFO by use of logistic regression analysis. RESULTS: Ten (12%) horses, all of which had RPFO, developed signs of colic after surgery. Horses > or = 5 years old that underwent orthopedic procedures of > 60 minutes' duration and that did not receive phenylbutazone after surgery were at significant risk for developing RPFO. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that after surgery unrelated to the gastrointestinal tract in horses, there is an intermediate clinical phase characterized by reduced fecal output preceding overt signs of colic. Recognition of RPFO may reduce morbidity and mortality of such horses.     

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.     

Association between Hyperglycemia and Survival in 228 Horses with Acute Gastrointestinal Disease

Background: Glucose homeostasis is dysregulated in critically ill humans resulting in hyperglycemia and decreased survival. Hyperglycemia is common in horses presenting with abdominal crisis, and this might be associated with a worse prognosis for survival.
Objective: To determine if hyperglycemia in horses with acute abdominal disease is associated with increased odds of failure to survive to hospital discharge.
Animals: Two hundred and twenty-eight adult horses with acute gastrointestinal disease.
Methods: Observational retrospective study. Records of horses > 1 year of age presenting for treatment of colic over a 3-year period were reviewed. Data collected included age, duration of colic, glucose, heart rate, PCV, total protein, anion gap, cost of hospitalization, breed, sex, pain at admission, diagnosis, whether surgery was performed, and life status at hospital discharge. Potential risk factors for nonsurvival were screened by univariable logistic regression and the best-fitting univariable model was used as the basis for multivariable regression modeling.
Results: Mean blood glucose was 155 mg/dL (8.5 mM) with 45% of the population above the reference range; 16.7% (38 of 228) of horses had severe hyperglycemia (>195 mg/dL; 10.7 mM). Factors associated with increased odds of failure to survive included glucose, severity of pain at admission, heart rate, PCV, anion gap, and diagnosis. The best-fitting multivariable model included glucose and diagnosis, with age included as a confounding variable. The model correctly classified outcome for 92.5% of horses.
Conclusions and Clinical Importance: This study has confirmed prior reports that hyperglycemia is common in horses with colic and is associated with a worse prognosis for survival to hospital discharge.     

A retrospective evaluation of the effect of perianesthetic hydromorphone administration on the incidence of postanesthetic signs of colic in horses

ObjectiveTo describe the incidence of postanesthetic signs of colic (PASC) in horses and determine if perianesthetic administration of hydromorphone was associated with an increased risk of PASC.Study designRetrospective, cohort study.AnimalsA total of 409 horses.MethodsAnesthesia and clinical records of horses admitted for various procedures from July 2018 to September 2019 were reviewed. Signs of colic and interventions were recorded up to 48 hours after anesthesia. A binomial logistic regression model was used to evaluate the association between the type of surgery, administration of hydromorphone, the duration of anesthesia and the incidence of PASC.ResultsOverall, 25 (6.1%) horses developed PASC within 48 hours of general anesthesia. Of 60 horses that underwent colic surgery, 16 (26.7%) developed PASC. Of 349 horses that underwent noncolic procedures, nine (2.6%) developed PASC. Thus, the incidence of PASC was higher in horses that underwent colic surgery than in horses that underwent noncolic procedures [odds ratio (OR) = 13.74 (5.73–32.95)]. No effect of hydromorphone on the incidence of PASC was identified [OR = 1.61 (0.71–3.62)]. Longer procedures (>2 hours) were identified as an independent risk factor for PASC [OR = 4.13 (1.52–11.22)].ConclusionsNo association between hydromorphone and an increase in the incidence of PASC was identified. Anesthesia for colic surgery and duration of anesthesia were associated with an increased risk of PASC.Clinical relevanceHydromorphone did not increase the incidence of PASC in this population.     

Prevalence of and Risk Factors for Postoperative Ileus after Small Intestinal Surgery in Two Hundred and Thirty-Three Horses

Objectives— To determine the incidence of postoperative ileus (POI) in a population of horses after small intestinal surgery and the effect of multiple variables on development of POI.
Study Design— Case series.
Animals— Horses (n=233) aged ≥1 year that had exploratory celiotomy for small intestinal disease that recovered from surgery from 1995 to 2005.
Methods— Sixty-eight variables were collected from medical records (1995–2005) for each horse. POI was defined as nasogastric reflux volume >20 L over 24 hours or >8 L at any single time after surgery.
Results— Twenty-seven percent (64/233) of horses developed POI; 29 of 64 (46%) horses with POI had duodenitis proximal jejunitis (DPJ). When no intestinal resection was required at surgery, excluding horses with DPJ, 15% of horses had POI; 30% horses had POI after intestinal resection. Ten percent of horses had POI for >24 hours. When horses with DPJ were excluded, factors associated with increased risk of POI included high packed cell volume at hospital admission ( P =.024), increasing age ( P =.0004), and length of intestinal resection ( P =.05).
Conclusions— Risk factors for POI in this study were nonspecific although horses with intestinal resection are at higher risk compared with horses without intestinal resection.
Clinical Relevance— Predicting with certainty which cases will develop POI remains elusive.     

Risk factors for colic in horses after general anaesthesia for MRI or nonabdominal surgery: absence of evidence of effect from perianaesthetic morphine

REASON FOR PERFORMING STUDY: Post anaesthetic colic is a recognised risk of general anaesthesia (GA), but causes are poorly understood. OBJECTIVES: To identify risk factors for development of colic following GA for magnetic resonance imaging (MRI) or nonabdominal surgery and to test whether the use of perianaesthetic morphine was associated with an increased risk of post anaesthetic colic. METHODS: A total of 553 anaesthetic and clinical records of 500 horses anaesthetised at the Animal Health Trust were analysed, 342 (62%) involved MRI and 211 (38%) nonabdominal, predominantly orthopaedic surgery. Multivariable logistic regression analysis was used to examine the association between post anaesthetic colic and explanatory variables, including use of perianaesthetic morphine. RESULTS: Twenty horses (3.6%) developed colic within 7 days of GA. A significantly larger (P = 0.001) proportion of the surgical cases developed post anaesthetic colic (7.1%) compared with MRI cases (1.5%). Having controlled for the effect of MRI/surgeon, there was evidence for a significantly increased risk of colic associated with maintenance of anaesthesia with isoflurane and administration of benzyl penicillin and/or ceftiofur. A reduction in risk of colic was associated with premedication with romifidine, longer duration of anaesthesia and sedation within 2 days of GA. Perianaesthetic morphine administration was not associated with increased risk. CONCLUSIONS: This study identified apparently novel risk factors for colic in horses following GA. Use of morphine was not found, after controlling for other MRI and surgery related risk factors, to be associated with an increased risk. The low prevalence of colic after GA and resulting low study power mean that further larger, multicentre collaborative studies are warranted to corroborate findings in this study. POTENTIAL RELEVANCE: Better knowledge of risk factors should lead to achievable measures to reduce frequency of occurrence.     

Determination of lactate concentrations in blood plasma and peritoneal fluid in horses with colic by an Accusport analyzer

BACKGROUND: Intestinal hypoperfusion can lead to increased lactate concentrations in plasma and peritoneal fluid of horses with colic. HYPOTHESIS: The purposes of this study were to (1) evaluate the reliability of the Accusport analyzer to assess peritoneal fluid lactate (PFL) concentrations in healthy horses and those with colic, (2) identify clinical features associated with abnormal blood plasma lactate (BPL) and PFL concentrations, and (3) evaluate the prognostic value of BPL and PFL. ANIMALS: BPL and PFL were determined in 20 healthy horses and in 106 horses with colic. RESULTS: The Accusport was reliable for determining BPL concentrations < 13 mM and PFL concentrations < 20 mM. Multivariate analysis indicated that PCV and the need for intestinal resection were independently associated with the BPL; pulse, PCV, venous pO2, the presence of necrotic intestine, an increased amount of peritoneal fluid, and fluid total protein content were independently associated with PFL. With a 1 mM increase in BPL or PFL, the respective odds ratios for required abdominal surgery increase to 1.23 (BPL) and 1.58 (PFL), odds ratios for a required intestinal resection increase to 1.20 (BPL) and 1.41 (PFL), and odds ratios for developing ileus increase by 1.33 (BPL) and 1.36 (PFL). PFL concentrations of 1, 6, 12, and 16 mM correspond to a probability of death of 11, 29, 63, and 82%, respectively, in horses without strangulating obstruction and of 25, 52, 82, and 92%, respectively, in horses with strangulating obstruction. CONCLUSION: PFL is more useful and sensitive than BPL for prognostic purposes in horses with colic.     

Prevalence of Electrolyte Disturbances and Perianesthetic Death Risk Factors in 120 Horses Undergoing Colic Surgery

The objective of this study was to determine the prevalence of intraoperative electrolyte disturbances and risk factors associated with perianesthetic death in horses undergoing colic surgery. The files of 120 horses meeting the inclusion criteria were reviewed. Data retrieved from the medical records, including demographic data and the occurrence of electrolyte disturbances and other intraoperative complications, were analyzed with a two step-approach by univariate and multivariate logistic regression models. Hypocalcemia was the most represented electrolyte disturbance (52.5%), followed by hypokalemia (30.0%) that was associated with intraoperative administration of salbutamol (P = .045). Perianesthetic death occurred in 46 horses, accounting for an overall mortality rate of 38.3%. Risk factors associated with death were anesthetic duration (P = .001), body weight (P = .020), presence of gastric reflux before anesthesia (P = .021), and intraoperative tachycardia (P = .043) and acidosis (P = .025). The mortality in the study population was comparable to previously reported findings. Based on the study findings, it is advisable to optimize hemodynamics prior to anesthesia, in order to prevent intraoperative tachycardia that is associated with increased risk of death. Heavier horses and those with gastric reflux may have a higher risk of fatalities, and intraoperative salbutamol administration may contribute to hypokalemia.     

Orthopedic Infections in Equine Long Bone Fractures and Arthrodeses Treated by Internal Fixation: 192 Cases (1990–2006)

Objective: To determine the rate of postoperative infection (POI) for internal fixation repaired equine long bone fractures and arthrodeses and identify associated risk factors. Study Design: Case series. Animals: Horses (n=192) with fracture repair of the third metacarpal and metatarsal bones, radius, ulna, humerus, tibia, and femur, or arthrodesis with internal fixation. Methods: Medical records (1990–2006) were reviewed for signalment, anatomic location, fracture classification and method of repair, technique and surgical duration, bacterial species isolated, postoperative care, onset of POI, and outcome. Results: Of 192 horses (171 [89%] closed, 21 [11%] open fractures), 157 (82%) were discharged from the hospital. Infection occurred in 53 (28% horses), of which 31 (59%) were discharged. Repairs without POI were 7.25 times more likely to be discharged from the hospital. Closed fractures were 4.23 times more likely to remain uninfected and 4.59 times more likely to be discharged from the hospital compared with open fractures. Closed reduction and internal fixation was associated with a 2.5‐fold reduction in rate of POI and a 5.9 times greater chance for discharge from the hospital compared with open reduction and internal fixation. Females had a strong trend for increased POI when compared with colts and stallion but not geldings. Conclusions: Overall rate of POI was 28%. Fracture classification, method of repair, gender, and surgical duration were significant risk factors.