Survival and complication rates in 300 horses undergoing surgical treatment of colic. Part 1: Short-term survival following a single laparotomy

REASONS FOR PERFORMING STUDY: A minority of equine colic cases prove fatal unless treated surgically; however, few studies have considered long-term survival and complication rates, and few have attempted to identify factors that might affect outcomes. Such information is required for owners and veterinary surgeons to make informed decisions about the most appropriate treatment for individual cases. OBJECTIVES: To document short-term survival rates of 300 horses undergoing colic surgery and analyse factors that might have predisposed to short-term death. METHODS: History, clinical and surgical findings, treatments and outcomes of 300 surgical colic cases (1994-2001) were reviewed. Comparisons among groups of discrete data were made using chi-squared or Student's t tests as appropriate. Significance was set at P < 0.05, and 95% confidence intervals were calculated for percentages. RESULTS: The short-term survival rate (to discharge) was 70.3% for all horses and 83.1% for those recovering from anaesthesia; for horses that had a single laparotomy it was 87.2%. The most common reasons for death/euthanasia in the post operative period after a single laparotomy were persistent pain/colic, post operative ileus and grass sickness. Horses with lesions involving the small intestine and caecum had lower survival rates (75.2 and 66.7%, respectively) than those with large colon or small colon lesions (89.9 and 100%, respectively). The survival rate for ischaemic/strangulating lesions (68.9%) was lower than for simple obstructions (90.5%). CONCLUSIONS: Short-term survival of horses undergoing exploratory laparotomy for acute colic is dependent on many factors, including the nature of the underlying disease, cardiovascular status and post operative complications. POTENTIAL RELEVANCE: These retrospective studies may be used as a basis for prospective studies assessing treatments that could ultimately improve survival and decrease complication rates.     

A retrospective study of gastrointestinal disorders in a predominantly Austrian leisure horse referral hospital population

The aim of our retrospective study was to produce and analyse epidemiological data on gastrointestinal (GI) disorders of Austrian leisure horses. Case records of horses referred to the Equine Clinic of the Veterinary University of Vienna were collected from an electronic hospital information system using its search options. All cases reported to have suffered a GI disorder between March 2003 and February 2015 were selected. In this period of 4314 days, data of 1833 GI cases, mostly accompanied by colic signs, were analysed. The vast majority of our GI cases appeared in the abdominal parts of the GI tract 96% (1760/1833) while just 1.3% (24/1833) could be definitively attributed to oesophageal disorders, whereas in 2.7% (49/1833) of the cases a definitive diagnosis could not be made. The highest prevalence of GI disorders was seen in July and October/November. A breakdown of figures for cases clustered under the colic syndrome showed that colon impactions in left ventral large and/or pelvic flexure (35%) were the major problem followed by gastric disorders (18%), spasmodic colic (9%), enteritis (7%), caecal tympany (6%); caecal impaction (4%), colitis (3%), abnormal anatomical positions of large colon including complete and partial strangulation/volvulus, nephrosplenic entrapment of the left ventral and dorsal colon and right dorsal displacement of the large colon (3%) and small intestinal volvulus (2.7%). In 12% of the cases, the cause of the abdominal discomfort was likely idiopathic paralytic ileus. The searching tool of the electronic patient data also brought up cases with malabsorbtion/IBD syndrome and GI ruptures, both these contributed less than 1% of the referred GI cases. Results suggested that the causes of colic are diverse, but the major reasons for referred cases of colic in the east Austrian horse population are large colon impaction or displacements. Seasonal distribution and specific causes of gastrointestinal disorders should be considered essential components of the initial clinical assessment of horses presenting with colic.     

Equine colic: clinical epidemiology and associated risk factors in and around Debre Zeit

A prospective study was conducted to describe clinical epidemiology of equine colic in the Society for Protection of Animal Abroad and Donkey Sanctuary Project Clinic, at Debre Zeit, Ethiopia, from November 2014 to April 2015. The objectives were to describe clinical epidemiology of equine colic, to characterize the main types of equine colic, and to determine the major risk factors associated with equine colic. The method which was used in the study was attending clinical case of equine and assessing physiological parameters, fecal egg count, abdominal sounds, and rectal examination as well as questioner interviewing of the owners. The data were collected and analyzed using Statistical Package for Social Science. The incidence of colic was 10.3% in the study period. Colicky were typed as unknown, flatulent, impaction, spasmodic, and enterolithiasis. The proportion of case incidence were 63.1 (41/65), 33.8 (22/65), and 3.1% (2/65), in donkey, horse, and mule, respectively. The total mean (±SD) of temperature 37.80 ± 1.003, heart rate 57.54 ± 10.098, fecal egg count 236.922 ± 67.990, respiratory rate 30.92 ± 7.315, and packed cell volume 41.40 ± 10.221 were recorded. The case fatality rate of equine colic was 15.38% (10/65). There were statistically highly significant (p < 0.01) differences in impaction colic in relation to species. Interview with 183 equine owners revealed incidence of equine colic as the sixth major disease condition affecting equine. A long-term epidemiological study of the true representative population should be carried out to determine the incidence rate and associated risk factors of equine colic in the study area.     

Survival and complication rates in 300 horses undergoing surgical treatment of colic. Part 4: Early (acute) relaparotomy

REASONS FOR PERFORMING STUDY: Early (acute) relaparotomy after surgery for equine colic is widely considered to be an acceptable treatment option for management of certain post operative complications. However, there is relatively little published information about resulting complication rates and short- and long-term outcomes. OBJECTIVES: To document the proportions, indications, complication rates and survival rates of horses undergoing acute relaparatomy following colic surgery. METHODS: History, clinical findings, surgical findings and procedures, post operative treatments and outcome of 300 consecutive surgical colic cases (1994-2001) were reviewed. Long-term follow-up information was retrieved from case records and telephone enquiries from owners. RESULTS: Acute relaparotomy was performed in 27/254 horses (10.6%) that recovered from initial general anaesthesia. The indications for relaparotomy included persistent pain, persistent ileus, peritonitis and wound breakdown. Of these 27 horses, 21 (77.8%) recovered from the second surgery, of which 8 (29.6%) died during the immediate post operative period. Thirteen of the 27 horses (48.2%) were discharged. Of these 13 horses, 5 (38.5%) were re-admitted to the hospital for surgical treatment of a subsequent bout of colic. The long-term survival rate for the 27 horses that underwent relaparotomy was 22.2%. Colic following discharge after relaparotomy was recorded in 69.2% of cases. CONCLUSIONS: Relaparotomy is necessary in approximately 10% of horses undergoing surgery for acute colic. Persistent pain and post operative ileus were the most common indications. The short-term survival rate for horses requiring relaparotomy was approximately 50% and the long-term survival rate 22%. Nearly 40% of horses surviving relaparotomy developed episodes of acute colic that necessitated further surgery. POTENTIAL RELEVANCE: Owners of horses requiring early (acute) relaparotomy should be advised of the high complication rates for this procedure.     

Types of colic and frequency of postcolic abortion in pregnant mares: 105 cases (1984-1988)

The records of 105 pregnant mares and 105 nonpregnant horses with colic admitted to an equine hospital were reviewed. The 2 groups had similar types of colic and short-term survivability. Of the 105 pregnant mares, 31 were treated medically and 74 required surgical intervention. Thirty-three of the 105 mares died or were euthanatized. Thirteen (18%) of the 72 remaining mares aborted. Of 4 mares with severe medical cases, 2 died, 1 aborted, and 1 aborted and died. Of 27 horses with medical cases that required less intensive treatment, none died and 2 aborted. Of the 74 horses that required surgery, 45 survived to termination of pregnancy (foaling or abortion); 36 of these mares (80%) had a live foal. The type of surgical lesion had no effect on pregnancy outcome. Stage of gestation at initial examination, duration of anesthesia, or intraoperative hypoxia or hypotension had no effect on pregnancy outcome. However, when hypoxia occurred during colic surgery in the last 60 days of pregnancy, the mares either aborted or delivered severely compromised foals that did not survive.     

A two year, prospective survey of equine colic in general practice.

The records of 200 colic episodes, collected prospectively, over a two year period, from first opinion cases, were analysed and compared with a control sample selected at random from the same population. Analysis by colic type revealed 72% spasmodic/undiagnosed; 7% surgical; 5.5% flatulent; 5% pelvic flexure impactions; 9.5% other implications and 1% colitis. A possible predisposing cause was identified in 43% of the spasmodic/undiagnosed cases. The total incidence of colic in each age group showed no statistically significant differences from the control population. Stallions were significantly under represented in the colic population. When compared with the control sample the number of spasmodic/undiagnosed colic cases in the 5-10-year-old group and the number of surgical colics in the over 15-year-old group were significantly greater than expected. No statistically significant correlation was found when the seasonal incidence of colic was compared with monthly temperature, change in monthly temperature, monthly rainfall, and rainfall weighted for temperature.     

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.     

Survival and complication rates in 300 horses undergoing surgical treatment of colic. Part 2: Short-term complications

REASONS FOR PERFORMING STUDY: Few studies have assessed short- and long-term complication rates of horses following surgical treatment of colic, a potentially fatal condition. Complications can lead to patient discomfort and increased costs; knowledge of predisposing factors may help to reduce complication rates. OBJECTIVES: To document and analyse short-term complications in 300 horses undergoing colic surgery, and to assess some of the possible predisposing factors. METHODS: History, clinical findings, surgical findings and procedures, and post operative treatments of 300 consecutive surgical colic cases (1994-2001) were reviewed. Comparisons among groups of discrete data were made using chi-squared or Student's t tests as appropriate. RESULTS: Short-term complications in 227 horses following a single laparotomy included colic/pain (28.2%), incisional drainage or infection (26.9%), post operative ileus (13.7%), severe endotoxaemic shock (12.3%), jugular thrombophlebitis (7.5%), septic peritonitis (3.1%) and colitis/diarrhoea (2.2%). Horses with small bowel obstruction had a higher rate of post operative ileus than those with large bowel obstruction. Rates of post operative pain and shock were higher in horses with small colon rather than large colon obstruction, and in those that had an ischaemic rather than a simple obstruction. The rate of wound complications increased with increasing total plasma protein concentration at admission. Horses that had a repeat laparotomy had a higher rate of wound complications compared to those that had a single laparotomy. Application of a stent bandage was associated with a higher rate of wound complications than if no stent was applied; however, application of an incise drape over the wound for recovery was associated with a lower rate of wound complications than for horses that had no protective covering of the wound. CONCLUSIONS: The most common short-term post operative complications following colic surgery were pain, incisional drainage, ileus, endotoxaemiac shock and jugular thrombophlebitis. Some factors that appeared to predispose to these complications were identified. Although many of these factors related to the underlying disease process, a number of factors, including surgical techniques, were identified that might be amenable to modification. POTENTIAL RELEVANCE: Prospective studies to assess the effects of modifying these factors on survival rates should be performed.     

Ultrasonographic visualization of colonic mesenteric vasculature as an indicator of large colon right dorsal displacement or 180�� volvulus (or both) in horses

Visualization of colonic mesenteric vasculature during transabdominal ultrasonographic examination of horses with colic can be a predictor of right dorsal displacement of the large colon or 180° large colon volvulus, or both. Medical records of 82 horses having had surgical treatment of colic and having received a transabdominal ultrasonographic examination on admission were reviewed. Colonic mesenteric vessels were sonographically identified coursing laterally on the right side of the abdomen in 24 of the 82 cases. Horses with colonic vessels identified on ultrasound were 32.5 times more likely to be diagnosed at surgery with either large colon right dorsal displacement or 180° large colon volvulus than those in which vessels were not seen (P < 0.001). Visualization of colonic mesenteric vessels on ultrasound provided a sensitivity of 67.7%, specificity of 97.9%, positive predictive value of 95.8%, and negative predictive value of 81% for large colon right dorsal displacement or 180° large colon volvulus, or both.     

Surgical treatment of colic in American miniature horses: 15 cases (1980-1987).

A study of 15 American miniature horses (AMH) that underwent surgical treatment for colic was performed. Information obtained from the medical records included signalment, clinical signs, type and location of gastrointestinal lesion, and postoperative complications. All 15 AMH had intraluminal obstructions, attributable to feed impactions (11 horses), enteroliths (2), and sand (2). The most common location of obstruction was the small colon, which was involved in 9 of the 15 cases. All 15 AMH survived and were discharged from the hospital. Six of the 15 AMH underwent subsequent surgical treatment for abdominal disorders. Elapsed time between the first and second operations ranged from 1 month to 5 years. Intestinal adhesions were observed in all AMH that were surgically treated twice. Thus, despite the fact that most of the AMH had a simple intraluminal obstruction, 40% (n = 6) developed adhesions that required or complicated a second surgery. Of the 15 AMH, 87% (n = 13) survived at least 12 months after the initial exploratory celiotomy. These findings suggest that most surgical abdominal conditions in AMH can be corrected; however, precautions should be taken to avoid or minimize adhesion formation.     

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%.     

Initial investigation of mortality rates and prognostic indicators in horses with colic in Israel: A retrospective study

Reasons for performing study: Initial assessment of the mortality rates and prognostic indicators in horses with colic presented to a referral hospital in Israel. Objectives: To determine mortality rates and to identify potential prognostic indicators in horses undergoing treatment for colic. Methods: The medical records of 208 colic cases were reviewed and mortality rates calculated including 95% confidence intervals. Mortality rates in surgical cases were calculated separately for strangulating and nonstrangulating lesions as well as for lesions of the large and small intestines. Potential prognostic indicators were identified and evaluated by Student's t test or X² test, where appropriate. Those found to be significant (P<0.05) were evaluated in 2 logistic regression models; one including all horses with colic and one for surgical cases only. Results: The overall mortality rate was 51/208 (25%); 5/72 (7%) in medically treated cases, 46/136 (34%) in surgical cases, 30/50 (60%) in strangulating lesions and 15/85 (18%) in nonstrangulating lesions, 17/27 (63%) in cases involving small intestinal lesions and 28/108 (26%) in cases with large intestinal lesions. Clinical parameters found to be significantly associated with death by univariate analysis were medical/surgical treatment, location of lesion, severity of lesion, mucous membrane colour (MM), capillary refill time (CRT) and heart rate. Using a multivariate logistic regression model, including all cases, medical/surgical treatment, CRT and MM were found to be prognostic indicators and when using the surgical cases alone, only CRT and lesion severity remained related to mortality. Conclusions: Mortality rates were similar or better than those previously reported in most cases, however, studies from the USA and the UK published better success rates for small intestinal surgeries. Cultural attitudes toward euthanasia may be associated with mortality rates. Potential relevance: These results assist clinicians in providing an immediate prognosis based on clinical findings at presentation and contribute to an international database that may aid future research in improving treatment of colic.     

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.     

Transrectal decompression as a new approach for treatment of large intestinal tympany in horses with colic: Preliminary results

A common feature of colic in horses is tympany in the large intestine and medical treatment of this condition can be unsuccessful. In this article we describe and evaluate a new approach for decompression of large intestinal tympany in equine colic patients using transrectal puncture. We evaluated horses showing colic symptoms and colonic or caecal tympany and the final diagnosis, complications and final outcome were recorded for each horse. A special transrectal decompression device (TDD) was developed and used to perform transrectal decompression (TD) by gas aspiration. In order to assess pain reduction as a result of TD, heart rate (HR) was recorded before and after the decompression procedure. Twenty‐five horses were included in the study. In 17 cases, tympany was recognised as primary in origin while in 8 it was secondary to other conditions. A total of 33 TDs were performed and no horses developed short‐ or long‐term complications. All horses were alive after the first month post TD, while 5 died from diseases not related to TD. The TD could safely and easily be performed in all horses presenting tympany. Transrectal decompression can easily be performed, 2 or even 3 times to treat a single colic episode by using the transrectal device connected to a surgical aspirator. It was not possible from available information to relate the timing of HR decrease to resolution of colic or to administration of drugs because a retrospective study and all such data were not readily accessible. Our clinical results support the relevance of the TD as an elective treatment of primary large intestinal tympany, emergency treatment of tympany secondary to other surgical entities and as palliative treatment in surgical patients, in which surgery could not be achieved.     

Analysis of peritoneal fluid as a diagnostic aid in grass sickness (equine dysautonomia)

The analysis of peritoneal fluid is of value in the differential diagnosis of equine colic but its characteristics have not been evaluated in grass sickness. Peritoneal fluid was collected from 15 normal horses and from 11 cases of medical colic, 11 cases of surgical colic, 20 cases of acute grass sickness and 13 cases of subacute grass sickness. The fluid was analysed for its appearance, total and differential white cell count, specific gravity, total protein concentration and total and intestinal alkaline phosphatase activity. Fluid from cases of medical colic was normal in these respects. Surgical cases were unique in having bloodstained fluid with a high alkaline phosphatase activity. Grass sickness cases had a higher specific gravity and protein content than the cases of medical colic although the appearance of the fluid was similar. Grass sickness cases were distinguishable from cases of surgical colic on the basis of the appearance of the fluid and its lower alkaline phosphatase activity.     

Surgical management of sand colic impactions in horses: a retrospective study of 41 cases

OBJECTIVE: A retrospective review of the medical records of 41 horses requiring abdominal surgery for sand colic. RESULTS: The diagnosis of sand colic was made when sand was found to be the cause of impaction of the gastrointestinal tract during surgical exploration. The most common clinical signs at presentation were abdominal pain, abdominal distension and diarrhoea. A statistically significant association was found between the respiratory rate on arrival and short-term survival. Sand impaction at multiple locations was detected in one-third of the horses. Concurrent pathology was detected in half of the horses. Four horses were euthanased during surgery; of those that recovered from surgery, 35/37 (95%) were discharged from hospital. Short- and long-term complications were similar to those previously reported. Long-term (1 year) survival of the horses discharged was 100%. CONCLUSION: The good prognosis for horses undergoing surgery for the treatment of sand impaction supports early surgical intervention in cases where large amounts of sand are suspected.     

Accuracy of increased large-intestine wall thickness during ultrasonography for diagnosing large-colon torsion in 42 horses

Large-colon torsion is a common cause of colic in horses and has a worse prognosis and higher cost than other causes of surgical colic of the large colon. During large-colon torsion, the colon wall becomes thick due to vascular occlusion. Therefore, we hypothesized that detecting increased colon wall thickness during ultrasonography would be an accurate preoperative test for large-colon torsion. The sample population consisted of 42 horses that were admitted for surgical treatment of colic localized to the large colon. The diagnosis was confirmed at surgery or necropsy examination. Twelve (29%) of these horses were diagnosed with large-colon torsion. Duplicate ultrasonographic measurements of colon wall thickness were made at six abdominal locations and an average measurement was calculated. For four of these six sites, a significant difference (P < 0.005) was detected between horses with and without large-colon torsion. All four tests were moderately sensitive and highly specific for diagnosing large-colon torsion using five decision criteria. Using a ventral abdominal window, a colon wall thickness > or = 9 mm accurately predicted large-colon torsion in eight of the 12 horses (sensitivity, 67%; confidence interval [CI], 36-98%) and correctly predicted that large-colon torsion was absent in 28/28 horses (specificity 100%; CI, 98-100%). Intraobserver repeatability was assessed by evaluating the difference between the first and second measurements obtained, which was < or = 2 mm. Therefore, detecting increased large-colon wall thickness during ultrasonography is a reproducible and accurate preoperative test for large-colon torsion in horses with surgical colic localized to the large colon.     

Resection and Anastomosis of the Descending Colon in 43 Horses

Objectives: To determine (1) the short‐ (to hospital discharge) and long‐ (>6 months) term survival, (2) factors associated with short‐term survival, and (3) the perioperative course for horses with resection and anastomosis of the descending colon. Study Design: Multicentered case series. Animals: Horses (n=43) that had descending colon resection and anastomosis. Methods: Medical records (January 1995–June 2009) of 7 equine referral hospitals were reviewed for horses that had descending colon resection and anastomosis and were recovered from anesthesia. Retrieved data included history, results of clinical and clinicopathologic examinations, surgical findings, postsurgical treatment and complications, and short‐term survival (hospital discharge). Long‐term survival was defined as survival ≥6 months after hospital discharge. Results: Of 43 horses, 36 (84%) were discharged from the hospital. Twenty‐eight of 30 horses with follow‐up information survived ≥6 months. No significant associations between perioperative factors and short‐term survival were identified. Lesions included strangulating lipoma (n=27), postfoaling trauma (4), infarction (4), intraluminal obstruction (2), and other (6). Common postoperative complications included fever and diarrhea. During hospitalization 7 horses were euthanatized or died because of septic peritonitis (3), endotoxemia (3), and colic and ileus (1). Conclusions: Descending colon resection and anastomosis has a favorable prognosis for hospital discharge and survival ≥6 months. The most common cause of small colon incarceration was strangulating lipoma. Clinical Relevance: Complications include postoperative fever and diarrhea but the prognosis is good after small colon resection and anastomosis.     

Survey of 79 referral colic cases

The clinical, surgical and/or necropsy diagnosis of 79 horses admitted to a referral clinic for evaluation of colic are reported. Twenty-one horses were presented with conditions amenable to medical treatment and all were subsequently discharged. Exploratory laparotomies were performed on 44 horses during the present study, in some cases as a diagnostic procedure preceding euthanasia. In general, in surgical cases the mortality rate was highest for problems involving the small intestine, followed by those affecting the large colon and then the small colon. Postoperative sequelae included peritonitis, infarction, visceral rupture and acute circulatory failure. Colitis, visceral rupture and thromboembolic infarction generally had a fatal result. The overall recovery rate (for 79 horses) was about 50 per cent.     

Large Experimental Fistula of the Right Dorsal Colon in Horses

Studies in horses with experimental gastrointestinal fistulas may lead to rapid advancements in equine nutrition, as well as prevention and treatment of diseases such as colic and laminitis. The aim of this study was to devise a technique and a cannula to create a large fistula in the right dorsal colon (RDC). A total of 13 horses with normal gastrointestinal tract were used. After the administration of sedatives and local anesthetics, a segment of the right 16th rib was removed, a circular defect was created in the muscular wall, and the RDC was sutured to the muscular wall. The subcutaneous tissue and skin were closed over the attached RDC in eight horses (closed technique), or removed to expose the serosa of the colon sutured to the abdominal wall in five horses (open technique). A full thickness circular incision was made 2 to 6 weeks later to create a fistula. A cannula (diameter, 5 cm) made of natural rubber or silicon was inserted in the fistula. The open surgical technique was easier to perform and resulted in fewer complications. The cannula made of silicon resulted in less pruritus. One horse had a large colon torsion around the colopexy before fistula creation. One of the 12 fistulated horses had a large colon displacement 43 days after cannula insertion. These observations suggest that pexis of the RDC may predispose the horse to large colon displacement or volvulus. The open technique for the colopexy and the cannula made of silicon can be used for creation of a RDC fistula.