Evaluation of updated sepsis scoring systems and systemic inflammatory response syndrome criteria and their association with sepsis in equine neonates

Background

The original equine sepsis score provided a method of identifying foals with sepsis. New variables associated with sepsis have been evaluated, but the sepsis score has not been updated.

Objectives

To evaluate the sensitivity and specificity of 2 updated sepsis scores and the systemic inflammatory response syndrome (SIRS) criteria in regard to detecting sepsis in foals.

Animals

Two‐hundred and seventy‐three ill foals and 25 healthy control foals.

Methods

Historical, physical examination, and clinicopathologic findings were used to calculate the original sepsis score and 2 updated sepsis scores. SIRS criteria were also evaluated. Sepsis scores and positive SIRS scores were statistically compared to foals with sepsis.

Results

One‐hundred and twenty‐six foals were septic and 147 sick‐nonseptic. The original and updated sepsis scores were significantly higher in septic foals as compared to sick‐nonseptic and healthy foals. The sensitivity and specificity of the updated sepsis scores to predict sepsis were not significantly better than those of the original sepsis score. One‐hundred and twenty‐seven of 273 (46.5%) foals met the original SIRS criteria and 88/273 (32%) foals met the equine neonatal SIRS criteria. The original SIRS criteria had similar sensitivity and specificity for predicting sepsis as did the 3 sepsis scores in our study.

Conclusions and Clinical Importance

The updated sepsis scores did not provide improved ability in predicting sepsis. Fulfilling the original SIRS criteria provided similar sensitivity and specificity in predicting sepsis as the modified sepsis score and might serve as a diagnostic aid in identifying foals at risk for sepsis.

Congenital Cystic Polypoid Rectal Hamartoma in a Newborn Foal

A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.

Plasma Peak and Trough Gentamicin Concentrations in Hospitalized Horses Receiving Intravenously Administered Gentamicin

Background

Gentamicin is an aminoglycoside antimicrobial commonly used in horses at 6.6 mg/kg IV once daily. Therapeutic drug monitoring (TDM) can confirm desired peak concentration is reached for common bacterial isolates, and detect toxicosis associated with high trough values.

Objectives

Determine the relationship between gentamicin dose and plasma concentration in hospitalized horses, and identify a starting dose range to achieve peaks > 32 μg/mL.

Animals

Sixty‐five horses (2002–2010) receiving once‐daily gentamicin with TDM performed (N = 99 sets).

Methods

Retrospective study. Data from hospitalized horses including weight, dose, plasma peak, and trough gentamicin concentration, creatinine concentrations and presence of focal or systemic disease were collected from medical records. Peak concentrations measured 25–35 minutes after administration were included (N = 77). Data were divided into low (<7.7 mg/kg), medium (7.7–9.7 mg/kg) and high (>9.7 mg/kg) dose groups, and were grouped by the horse having focal or systemic disease.

Results

Peak concentrations resulting from doses ≥7.7 mg/kg were 5.74 μg/mL (SE 2.1 μg/mL) greater than peaks from doses <7.7 mg/kg (P = .007). Peak concentrations was 3.6 times more likely to be >32 μg/mL if dose was ≥7.7 mg/kg (P = .04). There were no significant effects of dose on trough or creatinine concentration. At a given dose, horses with focal disease had higher peaks than those with systemic disease (P = .039).

Conclusions and Clinical Importance

These data suggest gentamicin dosage should be individually determined in horses using TDM, but support an initial once‐daily dose of 7.7–9.7 mg/kg IV to achieve peaks >32 μg/mL and trough concentrations <2 μg/mL. Further studies evaluating the safety of doses >6.6 mg/kg are required.

Association of admission L-lactate concentration in hospitalised equine neonates with presenting complaint, periparturient events, clinical diagnosis and outcome: a prospective multicentre study

REASONS FOR PERFORMING THE STUDY

Admission L-lactate concentration is a useful and commonly measured biomarker not previously prospectively evaluated in a large multicentre study of critically ill neonatal foals.

OBJECTIVES

To evaluate overall outcome and the association of survival and L-lactate concentration at admission ([LAC]ADMIT) by periparturient history, presenting complaint and clinicians' major diagnosis for ill neonatal foals.

METHODS

Thirteen university and private equine referral hospitals enrolled 643 foals over the 2008 foaling season. Case details, historical, clinical and clinicopathological data were entered into standardised spreadsheets then unified for analysis.

RESULTS

Overall survival was 79% (505/643). Risk of nonsurvival increased with each 1 mmol/l increase in [LAC]ADMIT (odds ratio 1.14, P < 0.001). Mean arterial pressure had a small (r2 = 19.1) but significant (P < 0.001) association with [LAC]ADMIT. Foals experiencing known dystocia or premature placental separation had increased [LAC]ADMIT (P < 0.001). Single umbilical problems (excluding uroperitoneum), meconium impaction only and failure of passive transfer of immunity only had 100% survival. Six clinicians' major diagnoses had increased odds of nonsurvival for each 1 mmol/l increase in [LAC]ADMIT: 'sepsis'; 'unspecified enterocolitis'; 'unspecified colic'; 'unspecified trauma'; 'immune related (not failure of passive transfer of immunity)' and 'respiratory only'.

CONCLUSIONS AND POTENTIAL RELEVANCE

Survival of critically ill foals is good but varies with peripartum history, presenting complaint and clinicians' major diagnosis. L-lactate concentration at admission proves its utility as a valuable prognostic biomarker in neonatal foals and its utility appears to vary with peripartum history and clinicians' major diagnosis.

Sequential plasma lactate concentrations as prognostic indicators in adult equine emergencies

BACKGROUND

Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate.

HYPOTHESIS

Prognosis for survival is decreased in horses with a delayed return to normal [LAC].

ANIMALS

Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement.

METHODS

Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC]deltaT) was calculated from changes in [LAC] between sampling points.

RESULTS

Median [LAC] was significantly (P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60-18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30-13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17-1.43) at admission to 49.90 (6.47-384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC]deltaT was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24-72 hours (- 0.47, P = .001) and 48-72 hours (- 0.07, P = .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors.

CONCLUSIONS AND CLINICAL IMPORTANCE

These results indicate that lactate metabolism is impaired in critically ill horses and [LAC]deltaT can be a useful prognostic indicator in horses.

Retrospective study of dystocia in mares at a referral hospital

REASONS FOR PERFORMING STUDY

The period between the onset of dystocia and its resolution has an important bearing on fetal outcome. There are few published data on which to base decisions regarding optimum management of cases in practice.

OBJECTIVES

To evaluate and compare the effects of a coordinated dystocia management protocol (CDMP) with that of a previous protocol of random management on time to resolution and outcome in both an emergency dystocia referral population of mares (referred emergency cases: EM) and in a population of mares residing in hospital due to high risk pregnancy (HRP) concerns that then experience dystocia at parturition.

METHODS

Retrospective study performed at a university hospital referral centre of cases presenting from 1991-2004 divided into Group 1 (pre-CDMP) and Group 2 (CDMP).

RESULTS

Medical records of 71 cases with dystocia were retrieved and data recorded. For referred emergency cases (EM), time from hospital presentation to resolution decreased significantly by 32 min (P = 0.03) after institution of CDMP. Survival rate of mares at discharge was 86%. Survival of EM foals was low, with 10% in Group 1 and 13% in Group 2, surviving to discharge. For EM foals delivered alive, survival to discharge was 30% and 43% in Groups 1 and 2, respectively. Median Stage II was significantly (P < 0.001) different at 71 and 282 min for EM foals delivered alive vs. those not alive at delivery, respectively. Median duration of Stage II was also significantly (P < 0.001) different between EM foals surviving and not surviving to discharge, at 44 and 249 min, respectively. Survival of HRP dystocia foals to discharge was 79%.

CONCLUSIONS

Although CDMP reduced the time from presentation at the hospital to resolution significantly for EM, total duration of Stage II for EM was unchanged, as was foal outcome.

POTENTIAL RELEVANCE

Very early referral of mares with dystocia to referral centres with dystocia management protocols may improve fetal outcome as increased duration of Stage II in the horse affects fetal outcome negatively.

Prospective evaluation of coagulation in critically ill neonatal foals

BACKGROUND

Coagulopathy is a potentially underrecognized complication of sepsis and septic shock in critically ill neonatal foals.

HYPOTHESIS

Critically ill neonatal foals have abnormalities in coagulation that are associated with disease severity and outcome.

ANIMALS

Foals <72 hours old admitted to a neonatal intensive care unit.

METHODS

Prospective, observational study. Blood was collected at admission, 24, and 48 hours for platelet count, prothrombin time, activated partial thromboplastin time, antithrombin activity and concentrations of fibrin degradation products, and fibrinogen in plasma from all foals.

RESULTS

Sixty-three foals were enrolled and classified as Septic Shock (12), Septic (28), and Other (23). At least 1 abnormal value was found in 18/28 (64%) samples from the Septic Shock group, 66/85 (78%) from the Septic group, and 30/59 (51%) from the Other group (P= .01). Coagulopathy (3 or more abnormal values) was present in 7/28 (25%) samples in the Septic Shock group, 14/85 (16%) samples in the Septic group, and 3/59 (5%) samples in the Other group (P= .0028). Clinically detectable bleeding occurred in 8/12 (67%) Septic Shock cases, 11/28 (39%) Septic cases, and 3/23 (13%) Other cases (P= .009). Foals in Septic Shock were 12.7 times more likely to have clinical evidence of bleeding than those in the Other group (95% CI 2.3-70, P= .004). Treatment with fluids or plasma did not have a detectable effect on coagulation values.

CONCLUSIONS AND CLINICAL IMPORTANCE

Coagulopathy commonly occurs in critically ill neonatal foals, especially those with sepsis and septic shock.

Comparison of the Accu-Chek Aviva point-of-care glucometer with blood gas and laboratory methods of analysis of glucose measurement in equine emergency patients

BACKGROUND

More information is needed regarding accuracy of commonly used methods of glucose measurement in the critically ill horse.

HYPOTHESIS

Glucometry will have good agreement with a laboratory standard. Glucometry with plasma will have better agreement than when performed with whole blood.

ANIMALS

Fifty sequentially admitted equine emergency patients, aged >1year.

METHODS

Venous blood was collected at admission and immediately analyzed by point-of-care glucometry on both whole blood (POC/WB) and plasma (POC/PL), a multielectrode blood gas analyzer with whole blood (BLG), and a standard laboratory method with plasma (CHEM). Paired data were compared using Lin's concordance correlation, Pearson's correlation, and robust regression. Bias and limits of agreement were tested by the Bland-Altman technique. Bivariate regression analysis was used to explore confounding factors.

RESULTS

Concordance was significant for all comparisons, and was strongest for CHEM-POC/PL (0.977) and weakest for POC/WB-POC/PL (0.668). Pearson's correlation was excellent for all comparisons except those with POC/WB. All comparisons had excellent robust regression coefficients except those with POC/WB.

CONCLUSIONS AND CLINICAL IMPORTANCE

POC glucometry with plasma had excellent agreement with a laboratory standard, as did blood gas analysis. POC glucometry with whole blood correlated poorly with a laboratory standard. These differences may be clinically important, and could affect decisions based on glucose concentrations.

Hepatic encephalopathy in a pregnant mare: identification of histopathological changes in the brain of a mare and fetus

An 11-year-old Thoroughbred broodmare was evaluated for suspected hepatic dysfunction. Clinical signs of hepatic encephalopathy were evident at admission. Hepatic ultrasonographic evaluation revealed an increase in hepatic size, rounded borders and normal echogenicity. There was no evidence of cholelithiasis or bile duct distention. Increased activity of hepatic enzymes, increased bile acid and bilirubin concentration and an increased ammonia concentration were supportive of a diagnosis of hepatic disease and hepatic encephalopathy. Histopathological evaluation of a liver biopsy specimen was consistent with chronic active hepatitis. The mare was treated with intravenous fluids and antimicrobials, pentoxyfilline, branched-chain amino acids and dietary manipulation. Clinical improvement was observed initially; however, 3 weeks later, deterioration in the mare's condition necessitated euthanasia. Pathological lesions at necropsy were restricted to the liver and brain. The liver was diffusely firm with a prominent reticular pattern on the cut surface. A large choledocholith was present in the main bile duct of the left liver lobe. Histopathological examination of the liver revealed severe fibrosis, with hyperplastic bile ducts and mononuclear and neutrophilic inflammation. Pathological changes consistent with hepatic encephalopathy, (Alzheimer type II cells), were evident in the cerebrum of both the mare and the fetus.

Extravascular lung water in the exercising horse

Seven Standardbred horses were exercised on a treadmill at speeds (approximately 12 m/s) producing maximal heart rate, hypoxemia, and a mean pulmonary arterial pressure of approximately 75 mmHg. Extravascular lung water was measured by using transients in temperature and electrical impedance of the blood caused by a bolus injection of cold saline solution. Lung water was approximately 3 ml/kg body wt when standing but did not increase significantly with exertion. We conclude that any increase in fluid extravasation from the pulmonary hypertension accumulates in the lung at a level that is less than that detectable by this method. At maximal exertion, the volume of blood measured between the jugular vein and the carotid artery increased by approximately 8 ml/kg, and the actively circulating component of the systemic blood volume increased by approximately 17 ml/kg with respect to corresponding values obtained when walking before exertion. These volume increases, reflecting recruitment and dilatation of capillaries, increase the area for respiratory gas exchange and offset the reduced transit times that would otherwise be imposed by the approximately eightfold increase in cardiac output at maximal exertion.

Clinical, pathologic, immunohistochemical, and virologic findings of eastern equine encephalomyelitis in two horses

Natural eastern equine encephalitis alphavirus (EEEV) infection was diagnosed in two adult horses with anorexia and colic, changes in sensorium, hyperexcitability, and terminal severe depression. Myocardium, tunica muscularis of stomach, intestine, urinary bladder, and spleen capsule had coagulative necrosis and perivascular lymphocytic infiltrate. Central nervous system (CNS) lesions were diffuse polioencephalomyelitis with leptomeningitis characterized by perivascular T lymphocyte cuffing, marked gliosis, neuronophagia, and multifocal microabscesses. Lesions were more prominent within cerebral cortex, thalamus, hypothalamus, and mesencephalon. EEEV was identified in the cytoplasm of cardiac myocytes and smooth muscle cells of spleen, stomach, intestine, urinary bladder, blood vessels, and dendritic cells. In the CNS, EEEV-positive cells included neurons, astrocytes, oligodendrocytes, microglia, and neutrophils. EEEV was isolated from the CNS of both horses. The detailed description of the encephalic and spinal EEEV localization and the findings of EEEV in extraneural tissues contribute to the understanding of this important multisystemic zoonotic disease.

Fatal nonneurological EHV-1 infection in a yearling filly

A case of fatal nonneurological equine herpesvirus 1 (EHV-1) infection in a yearling filly is described. Gross lesions included extensive pulmonary edema, prominent laryngeal lymphoid follicles, and congestion and edema of the dorsal third ventricle choroid plexus. Histologically, there was vasculitis, hemorrhage, and edema in the lungs and dorsal third ventricle choroid plexus as well as mild intestinal crypt necrosis with occasional intranuclear inclusion bodies. The perivascular and vascular inflammatory infiltrates were comprised mainly of T lymphocytes and macrophages. EHV-1 antigen was identified within the nucleus and cytoplasm of endothelial cells, dendritic-like cells of the pharyngeal lymphoid follicles, pharyngeal glandular epithelium, crypt enterocytes, and monocytes. Attempted virus isolation was negative. Weak seroconversion for EHV-1 was observed. Herpesvirus-like particles were identified within pharyngeal endothelial cells by transmission electron microscopy. Polymerase chain reaction amplified 369 and 188 base-pair fragments specific for EHV-1. The scarcity of pathognomonic viral inclusions and lesions in this case suggests that this disease may not be recognized, particularly in situations when ancillary laboratory procedures are limited.

Listeria monocytogenes septicemia in a Thoroughbred foal

Listeria monocytogenes septicemia was diagnosed in a 6-day-old Thoroughbred foal. Primary clinical signs included fever, depression, diarrhea, and respiratory distress. Hematologic abnormalities included leukopenia, neutropenia, degenerative left shift, and hyperfibrinogenemia. Clinical chemistry and blood gas abnormalities included metabolic acidosis, hypoxemia, hypocapnia, hypoglycemia, and hyponatremia. Despite aggressive therapeutic intervention and intensive care, the foal died within 12 hours of admission. A postmortem examination was performed, and the primary gross lesion was bilaterally severe, focally extensive bronchopneumonia. Histopathology revealed severe subacute multifocal suppurative bronchopneumonia with necrotizing vasculitis and intralesional coccobacilli. Cultures of blood collected at admission and immediately prior to death were positive for L. monocytogenes, as were cultures obtained from lung and liver at necropsy. Immunohistochemical examination of formalin-fixed tissues revealed abundant intra- and extracellular L. monocytogenes antigen within the lung and intravascularly in multiple organs.

Clinical, haematological and biochemical findings in foals with neonatal Equine herpesvirus-1 infection compared with septic and premature foals

A retrospective multicentre study comparing historical, clinical, haematological, acid-base and biochemical findings of foals with Equine herpesvirus-1 (EHV-1) infection, septicaemia or prematurity was performed to determine if early diagnosis of EHV-1 foals was possible. Fifty-three foals were studied and were assigned to one of 2 groups: herpes positive (n = 14) or herpes negative (n = 39). The latter group included 20 septic, 11 premature, and 8 premature and septic foals. The presence of herpes antigen was confirmed by immunoperoxidase histochemical staining of tissues from necropsied foals. A nonparametric statistical analysis followed by a backwards elimination logistic regression was performed to establish a model at a P value of <0.05. All herpes positive foals died, while 47% (9/19) of the septic foals survived. Based upon our analysis, herpes positive foals were more likely to have total white blood cell counts less than 3 x 10(9)/l and to be icteric as compared to the septic and premature foals. Despite profound hepatic necrosis in the herpes positive foals, liver enzymes were not elevated and were not significantly different from the controls.

Equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations

Clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (EAV) epidemics in newborn foals. Outbreak A occurred at a commercial Standardbred breeding facility; Outbreak B began in a group of research animals. Clinical signs were severe and primarily referable to the respiratory tract. Fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. The most common gross pathological findings were limited to the respiratory tract. Common histopathological findings included interstitial pneumonia, lymphocytic arteritis and periarteritis with fibrinoid necrosis of the tunica media. Renal tubular necrosis was noted in 2 foals. Immunoperoxidase histochemistry combined with virus isolation was diagnostic in all cases.

Negative pressure pulmonary edema as a post-anesthetic complication associated with upper airway obstruction in a horse

An 8-year-old Trakehner mare developed fulminant pulmonary edema following suspected upper airway obstruction 50 minutes into an otherwise unremarkable anesthetic recovery after surgery for left cricoarytenoideus dorsalis muscle reinnervation and ventriculocordectomy. Establishing a patent airway by orotracheal reintubation and cardiopulmonary resuscitation attempts were unsuccessful. Gross, histological, and electron microscopic postmortem examination showed severe hemorrhagic pulmonary edema. Laryngeal swelling or hemorrhage were not evident, suggesting laryngospasm or functional airway collapse associated with the underlying left laryngeal paralysis, as a cause of the upper airway obstruction. Negative pressure pulmonary edema is rarely reported in the veterinary literature as a postanesthetic complication.

Measurements of blood flow and xanthine oxidase activity during postischemic reperfusion of the large colon of ponies

To assess right colic artery blood flow and relevance of xanthine dehydrogenase/xanthine oxidase after experimentally induced strangulation obstruction and reperfusion of the colon, 5 ponies were subjected to 2.5 hours of complete ischemia of the left dorsal and ventral colons, allowed to recover from surgery, and monitored during a 48-hour reperfusion period. Five ponies were subjected to sham surgery and served as controls. All ponies had a Doppler ultrasound blood flow monitor implanted on the right colic artery near the pelvic flexure 10 to 14 days prior to the ischemic period. Colic artery blood flow was monitored prior to, during, and for 4 hours after surgery. Blood samples from the right colic artery and vein distal to the obstruction site were collected during surgery (prior to ischemia, after 1 and 2 hours of ischemia, and after 10 and 60 minutes of reperfusion) for determination of arterial and venous blood gas tensions and electrolytes. Prior to surgery, blood selenium and plasma vitamin E (alpha-tocopherol) concentrations and blood glutathione peroxidase (GPX) activity were determined to assess the status of endogenous antioxidants. Combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone (nanomoles per minute per gram of tissue) were determined, using a dual-spectrophotometric technique. Xanthine dehydrogenase and oxidase activities were determined prior to ischemia, after 1 and 2 hours of ischemia, and at 1 and 48 hours after reperfusion. Median blood flow in the experimental and control groups (156 ml/min and 110 ml/min, respectively) was not statistically different before surgery, and was significantly (P < 0.02) lower in the experimental (4 ml/min) vs the control group (72.5 ml/min) during the ischemic period. Experimental ponies had significantly (P < 0.03) lower right colic artery blood flow during the 4 hours immediately after recovery from anesthesia. Significant difference was not observed in right colonic venous bicarbonate concentration between groups at any time. Median right colonic venous PCO2, pH, and standard base excess were different (P < 0.001) between groups during the ischemic period only. Median venous oxygen saturation and median venous PO2 were significantly (P < 0.001) lower in the experimental ponies at the end of 2 hours of ischemia, but were significantly (P < 0.05) increased during the reperfusion phase. Median venous potassium concentration was significantly (P < 0.01) higher in experimental ponies during the ischemic and reperfusion phases. Vitamin E and GPX values were within normal limits for all ponies.(ABSTRACT TRUNCATED AT 400 WORDS)

A herd outbreak of equine leukoencephalomalacia

Equine leukoencephalomalacia (ELEM) affected 6 of 10 pleasure horses in adjacent paddocks at a boarding facility. Four of the 6 affected horses died or were euthanized. Two of 3 horses presented for treatment survived with complete resolution of clinical signs. Treatment was primarily supportive. Dimethyl sulfoxide, dexamethasone, flunixin meglumine and thiamine were administered as anti-inflammatory agents and to decrease or prevent cerebral edema. Fusarium monileforme was cultured from ear corn fed the affected horses. Fumonisin B1, B2 and B3 were isolated.

Efficacy of intravenous plasma to transfer passive immunity in clinically healthy and clinically ill equine neonates with failure of passive transfer

The efficacy intravenous plasma to transfer passive immunity to clinically healthy colostrum-deprived and clinically ill foals with failure of passive transfer was investigated. Efficacy of transfer was evaluated by the elevation of serum IgG per gram of IgG administered as a function of body weight. Colostrum deprived healthy foals had a significantly greater increase in serum IgG than did clinically ill foals with failure of passive transfer. Knowledge of the IgG content of plasma to be administered and the health status of a foal with failure of passive transfer should allow more accurate prediction of an individual foal's response to treatment.

Technique for long-term right dorsal colon fistulization in ponies

Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used for gastrointestinal experiments.

Xanthine oxidase formation during experimental ischemia of the equine small intestine

We hypothesized that xanthine oxidase plays a role in the postischemic reperfusion injury in the equine small intestine. Under anesthesia, four horses and two ponies underwent ischemic strangulating obstructions of segments of the proximal jejunum, mid-jejunum and ileum. Prior to vascular occlusion, and at 1 h and 2 h of ischemia, full-thickness intestinal biopsies were collected for histopathological evaluation and for determination of combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone. The level of XO activity was expressed in percentage according to the ratio of XO/(XDH + XO). We found a nearly threefold increase in the combined level of XDH plus XO activity from ileum to duodenum (p less than 0.04). However, the preischemic level of % XO activity did not vary significantly (p = 0.61) between segments of jejuno-ileum. Likewise, no significant difference was noted between intestinal segments after ischemia. Therefore, the data from all intestinal segments were pooled for each time and analyzed using Wilcoxon's signed rank test (one-tailed). Compared to the pre-ischemic level of % XO activity (median 27%), the % XO activity increased after 1 h of ischemia (median 37.0%), reaching statistical significance (p = 0.016). There were no statistical differences between the preischemic % XO activity and the % XO activity in non-ischemic bowel at the end of the anesthetic period. During ischemia, % XO activity increased, which lends credence to the importance of xanthine oxidase in previously-documented reperfusion injury in the equine small intestine.

The effect of hearing protectors on the attention demand of warning sounds

A reason often given by noise-exposed workers for not wearing their hearing protection is that it impairs their ability to hear important sounds such as acoustic warning signals. An experiment was therefore conducted to assess the possible effect of wearing hearing protection on the attention demand of a typical industrial warning sound. Inattention was created by providing uncertainty as to the time occurrence of the signal, and a separate loading task. The results indicate that neither inattention, nor the combination of inattention and the wearing of hearing protection, need necessarily impair the perception of a warning sound. The experiment therefore found no basis for the attitude that hearing protectors impair the effectiveness of warning sounds. This conclusion may not however apply to warning sounds which are not distinct from the ambient noise, those which have to be recognized amongst other discrete sounds, or to users of hearing protection with an existing noise-induced hearing loss.