A computer-derived protocol to aid in selecting medical versus surgical treatment of horses with abdominal pain

In order to determine which variables are useful in identifying horses with abdominal pain requiring surgery, data were analysed from 219 horses presented at one veterinary teaching hospital. Using multiple stepwise discriminant analysis with a recursive partitioning algorithm, we obtained a decision tree that identifies surgical and non-surgical patients. The prevalence of surgical patients was 79 per cent in this population. The sensitivity, specificity, and positive and negative predictive values of this decision tree were 99 per cent, 55 per cent, 90 per cent and 99 per cent respectively. Compared to the clinical decision, this decision tree yielded more false positives (11 per cent) but almost eliminated false negatives (1 per cent). This decision tree was validated by the jack-knife method and also by evaluation using a new sample in a second veterinary teaching hospital in which the prevalence of surgical patients was 55 per cent. This led to sensitivity, specificity and positive and negative predictive values of 93 per cent, 73 per cent, 81 per cent and 89 per cent respectively.     

Effects of aerobic and anaerobic fluid collection on biochemical analysis of peritoneal fluid in healthy horses and horses with colic

Objective: To determine whether in healthy horses and those with colic, exposure of peritoneal fluid to room air affects values obtained on biochemical analysis. Study Design: Prospective study. Animals: Adult horses with a primary complaint of acute abdominal pain (n=29) and 12 healthy horses. Methods: Peritoneal fluid was aseptically collected under aerobic and anaerobic conditions. After collection, pH, PCO₂, PO₂, HCO₃^?, Na⁺, ionized Ca²⁺, K⁺, lactate, and glucose were immediately measured using a commercial blood gas analyzer. Biochemical variables were compared between aerobically and anaerobically obtained samples using a paired t‐test. Results: In healthy horses, peritoneal fluid samples collected under anaerobic conditions had higher PCO₂ and ionized Ca²⁺ and lower PO₂, HCO₃^?, and pH compared with samples exposed to air. No differences were observed for K⁺, Na⁺, glucose, and lactate. In horses with colic, samples collected anaerobically had higher PCO₂, ionized Ca²⁺, Na⁺, and glucose and lower PO₂, HCO₃^?, and pH value compared with samples exposed to air. No differences were observed for K⁺ and lactate. Conclusion: Exposure of peritoneal fluid to room air had a significant effect on pH, PCO₂, PO₂, and variables associated or dependent on changes in pH such as HCO₃^? and ionized Ca²⁺. Interpretation of biochemical analysis of peritoneal fluid may be influenced by sample collection method.     

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.     

Results of surgical treatment of colic in miniature breed horses: 11 cases

OBJECTIVE: To report on the outcome of surgical treatment of acute abdominal crises in miniature breed horses. DESIGN: Retrospective case series of miniature horses presented to the University Veterinary Centre, Camden with an acute abdominal crisis. METHODS: Hospital records of all miniature horses that underwent ventral midline laparotomy for acute abdominal crisis between 1997 and 2001 were reviewed. The signalment, history, clinical signs, results of ancillary diagnostic procedures, location and type of intestinal lesion, treatment and outcome were retrieved from each case record. Long-term survival was determined by telephone interview of owners. RESULTS: Eleven miniature horses including five females and six males underwent ventral midline laparotomies for acute abdominal crisis during the study period. Ages ranged between 1 month and 19 years. Surgical findings included faecalith obstruction (seven horses), enterolith (one horse), strangulating lipoma of the descending colon (one horse), jejunal infarction (one horse), and caecal infarction (one horse). Long-term survival rate (minimum 12 months post surgery) was 55%. Six of eight horses with simple intraluminal obstructions survived, while the three horses with gastrointestinal lesions associated with vascular compromise were euthanased either at surgery (caecal infarction), or postoperatively, due to complications (strangulating lipoma of the descending colon, jejunal infarction). Postoperative complications in this study included impaction of the descending colon (two horses), diarrhoea (two horses), peritonitis (one horse), hyperlipaemia (two horses), incisional infection (two horses) and abdominal adhesions (one horse). Hyperlipidaemia was present in five of seven horses in which serum triglycerides were measured at presentation. CONCLUSIONS: Simple intraluminal obstructions of the large intestine were frequently encountered during exploratory laparotomy in miniature horses presented for acute abdominal crises, and their surgical treatment was associated with a good prognosis. In contrast, this study suggested that abdominal pain associated with vascular compromise of gastrointestinal tissues in miniature horses was associated with a poorer prognosis, consistent with reports in other horse breeds. Possible contributing factors to faecalith formation, including poor quality roughage, dental disease, and inadequate water consumption, should be recognised and avoided in miniature horses. Serum triglyceride concentrations should be measured in miniature horses presented for acute abdominal pain. If elevated, nutritional supplementation should be provided.     

Use of the Accusport semi-automated analyser to determine blood lactate as an aid in the clinical assessment of horses with colic

The most useful diagnostic methods in the initial evaluation of horses with colic assess the morphological and functional status of the gastrointestinal tract and cardiovascular status. This evaluation is best achieved using a combination of clinical and laboratory data. Blood lactate concentration (BL) is one of these variables. BL rises mainly due to poor tissue perfusion and anaerobic glycolysis associated with shock, providing an indicator of both the severity of disease and its prognosis. A hand-held lactate meter, Accusport, provides a rapid (60 seconds), inexpensive dry-chemical-based determination of BL. This trial evaluated the Accusport's ability to provide BL data as an adjunct to the initial clinical evaluation of horses with colic. The accuracy of the Accusport was tested by evaluation of its interchangeability with the benchmark enzymatic kit evaluation of BL in a trial using data collected firstly from 10 clinically normal control horses and subsequently from 48 horses presented with signs of colic. The BL values were recorded together with the clinical variables of heart rate (HR), capillary refill time (CRT), haematocrit (Hct), and pain character and severity on the initial assessment of the colic horses. Information regarding choice of therapeutic management (medical or surgical) and eventual case outcome (full recovery or died/euthanased) was recorded. The Accusport was found to be interchangeable with the enzymatic kit for recording BL values in colic horses with BL < 10 mmol/l, which is within the BL range associated with survival. The interchangeability of an additional, laboratory-based wet chemical assay for BL, the Stat 7 was simultaneously evaluated for the colic and control horses. The Stat 7 was found to be interchangeable with the enzymatic kit for BL determination of colic horses. No linear associations between BL values with HR, CRT, Hct or pain assessment were observed. No relationship with either selection of therapeutic method or eventual case outcome was observed. All horses with BL >8 mmol/l died or were euthanased.     

Diagnostic assessment of peritoneal fluid cytology in horses with abdominal neoplasia

Objective: To evaluate the diagnostic value of peritoneal fluid (PF) cytology for clinical diagnosis of abdominal neoplasia in horses. Material and methods: Ten horses with histopathologically confirmed abdominal neoplasia, in which a PF analysis was performed, were included in this retrospective study. PF was analyzed for total protein concentration and a nucleated cell count was performed. Using cytological criteria of malignancy, the PF samples were evaluated regarding their probability of malignancy. Results: Cytologic classification of cells according to criteria of malignancy allowed a positive cytologic diagnosis of neoplasia in 5 out of 10 peritoneal fluid samples. Malignant lymphoma was the most commonly diagnosed neoplasia (3/10) and could be identified by cytology in 2/3 cases. In 1/2 horses with plasma cell myeloma neoplastic cells were similarly found. Malignant melanoma (2/10) was diagnosed using cytology in one case (presence of melanin-containing cells). Cytological diagnosis of malignant neoplasia was established in the only horse with gastric squamous cell carcinoma, but the morphology of the identified tumour cells did not allow a specific diagnosis. Thus, a definitive diagnosis was achieved in 4/5 horses with proven abdominal neoplasia. The horses with adenocarcinoma (1/10) and haemangiosarcoma (1/10) had no evidence of neoplasia based on cytological findings. No relationship between total protein concentration or the nucleated cell count with the histolopathological diagnosis of abdominal neoplasia was found. Abnormal mitotic figures were considered of greater diagnostic value than the overall mitotic rate. Conclusion: The implementation of nuclear criteria of malignancy in the cytologic evaluation of PF samples allows the identification of neoplastic cells to an acceptable degree. For this purpose, the knowledge of the highly variable morphological features of mesothelial cells is essential. The absence of malignant cells does not rule out abdominal neoplasia. Clinical relevance: PF cytology should be considered as a valuable, minimally invasive, simple, and rapid diagnostic technique in horses with suspected abdominal neoplasia.     

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.     

Comparative biochemical analyses of venous blood and peritoneal fluid from horses with colic using a portable analyser and an in-house analyser

Fifty-six horses with colic were examined over a period of three months. The concentrations of glucose, lactate, sodium, potassium and chloride, and the pH of samples of blood and peritoneal fluid, were determined with a portable clinical analyser and with an in-house analyser and the results were compared. Compared with the in-house analyser, the portable analyser gave higher pH values for blood and peritoneal fluid with greater variability in the alkaline range, and lower pH values in the acidic range, lower concentrations of glucose in the range below 8.3 mmol/l, and lower concentrations of lactate in venous blood in the range below 5 mmol/l and in peritoneal fluid in the range below 2 mmol/l, with less variability. On average, the portable analyser underestimated the concentrations of lactate and glucose in peritoneal fluid in comparison with the in-house analyser. Its measurements of the concentrations of sodium and chloride in peritoneal fluid had a higher bias and were more variable than the measurements in venous blood, and its measurements of potassium in venous blood and peritoneal fluid had a smaller bias and less variability than the measurements made with the in-house analyser.     

Survival and complication rates in 300 horses undergoing surgical treatment of colic. Part 3: Long-term complications and survival

REASONS FOR PERFORMING STUDY: Few studies have evaluated long-term survival and complication rates in horses following surgical treatment of colic, making it difficult to offer realistic advice concerning long-term prognosis. OBJECTIVE: To review the complications occurring after discharge from hospital and survival to >12 months after surgery of 300 horses undergoing exploratory laparotomy for acute colic. Pre-, intra- and post operative factors that affected long-term complications and long-term survival were assessed. METHODS: History, clinical findings, surgical findings and procedures and post operative treatments 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: The long-term (>12 months) survival rate for 204 horses discharged after colic surgery and for which follow-up information was available was 84%. The most common complication after discharge was colic, affecting 35.1% of horses following a single laparotomy. Colic was most common in horses that had had small intestinal obstructions, bowel resection or post operative ileus. Abdominal adhesions were most common in horses that presented with severe colic due to strangulation of small intestine. Ventral hernia formation occurred in 8% of horses, and was most common in horses that had had post operative wound drainage or infection. CONCLUSIONS: This study identified various factors that appear to predispose horses to long-term complications after colic surgery. POTENTIAL RELEVANCE: Further evaluation of strategies that might reduce the incidence of such complications are needed; in particular, the value of intraperitoneal heparin should be evaluated, and procedures designed to reduce the rates of wound drainage and infection assessed.     

The diagnostic and prognostic value of alkaline phosphatase activity in serum and peritoneal fluid from horses with acute colic

Alkaline phosphatase (ALP) is an enzyme present in intestinal mucosa, bile, bone, and renal tubule cells. We sought to assess the diagnostic and prognostic relationships of total ALP (ALPt) activity and that of intestine-derived ALP (ALPi) in serum and peritoneal fluid of 126 horses with colic. ALPt and ALPi activities were measured in both serum and peritoneal fluid by using both standard and L-phenylalanine-based buffers, respectively. Neither ALPt nor ALPi activity were useful in classifying type or severity of intestinal damage. ALPt and ALPi activities in peritoneal fluid were lowest in horses suffering from simple medical colic (39 international units [U]/L [19-60 U/L]; versus 31 U/L [16-44 U/L], median [interquartile range], P < .001) and nonstrangulated surgical lesions (45 U/L [30-62 U/L] versus 36 U/L [23-54 U/L], P < .001), and highest in surgical cases with suspected ulceration (109 U/L [60-1,113 U/L] versus 83 U/L [52-970 U/L], P < .001), strangulation (114 U/L [69-240 U/L] versus 94 U/L [56-191 U/L], P < .001), peritonitis (313 U/L [110-2,227 U/L] versus 283 U/L [91-1,800 U/L], P < .001) or intestinal rupture (687 U/L [205-852 U/L] versus 564 U/L [166-732 U/L], P < .001). Higher ALPt and ALPi activities in peritoneal fluid were associated with greater intestinal damage, increased probability of surgery, and a worse prognosis. The use of L-phenylalanine buffer in both serum and peritoneal fluid did not improve the sensitivity of the test. Based on these results, total ALP activity in peritoneal fluid may help in identifying ischemic or inflammatory bowel lesions in horses with acute colic.     

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.     

Packed cell volume and heart rate to predict medical and surgical cases and their short-term survival in horses with gastrointestinal-induced colic

The objective of this prospective case-control study of 125 horses with gastrointestinal tract-induced colic was to determine whether heart rate (HR) and packed cell volume (PCV) can predict surgical versus medical treatment and its short-term survival (time of discharge of the patient). Sixty-four horses were treated medically and 61 surgically (29 small intestinal and 32 large intestinal cases). At admission, both PCV and HR were higher in horses treated surgically than in horses treated medically; however, with longer duration of colic before presentation, the PCV was higher in the small intestinal surgical group only. In addition, both PCV and HR were higher, and the duration of colic was longer in non-survivors compared to survivors. Binary logistic regression demonstrated a significant association between HR and type of treatment, and both HR and PCV were predictive of survival. Simple parameters such as HR and PCV provide useful information for management of colic cases.     

Evaluation of peritoneal fluid following intestinal resection and anastomosis in horses.

Postoperative abdominal fluid changes were compared in 2 groups of horses; those undergoing double small-colon resection and anastomosis (n = 10) and those undergoing exploratory celiotomy alone (n = 5). Peritoneal fluid was collected before surgery and on postoperative days 1, 3, 5, and 7. Total and differential nucleated cell counts, RBC numbers, and total protein and fibrinogen concentrations were evaluated. In both groups, all values were significantly higher than normal on the first postoperative day (after small-colon resection and anastomoses, WBC = 130,350 +/- 23,310 cells/microliters, RBC = 7,389,000 +/- 6,234,000 cells/microliters, total protein = 3.63 +/- 0.16 g/dl; after exploratory celiotomy alone, WBC = 166,620 +/- 34,340 cells/microliters, RBC = 295,000 +/- 86,070 cells/microliters, total protein 4.38 +/- 0.54 g/dl). The number of total peritoneal nucleated cells and RBC significantly decreased after the first postoperative day, whereas total protein and fibrinogen concentrations, percent neutrophils, and percent mononuclear cells remained unchanged. None of the values had returned to normal by postoperative day 7 (after small-colon resection and anastomoses, WBC = 45,600 +/- 8,765 cells/microliters, RBC = 95,390 +/- 53,380 cells/microliters, total protein = 4.39 +/- 0.23 g/dl; after exploratory celiotomy alone, WBC = 43,340 +/- 7,746 cells/microliters, RBC = 12,860 +/- 11,790 cells/microliters, total protein = 3.92 +/- 2.20 g/dl.) The resection and anastomosis group had a significantly lower total protein concentration on the first postoperative day and a significantly higher mean total RBC count over the entire 7-day postoperative evaluation than did horses that underwent celiotomy alone. Other values in the 2 groups of horses did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sparing the gut: COX-2 inhibitors herald a new era for treatment of horses with surgical colic

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to manage a wide variety of conditions in horses, including management of colic. Flunixin meglumine is by far the most commonly used drug in the control of colic pain and inflammation and has become a go-to for not only veterinarians but also horse-owners and nonmedical equine professionals. NSAID use, however, has always been controversial in critical cases due to a high risk of adverse effects associated with their potent cyclo-oxygenase (COX) inhibition. There are two important COX isoenzymes: COX-1 is generally beneficial for normal renal and gastrointestinal functions and COX-2 is associated with the pain and inflammation of disease. Newer selective NSAIDs can target COX-2-driven pathology while sparing important COX-1-driven physiology, which is of critical importance in horses with severe gastrointestinal disease. Emerging research suggests that firocoxib, a COX-2-selective NSAID labelled for use in horses, may be preferable for use in colic cases in spite of the decades-long dogma that flunixin saves lives.     

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.