Evaluation of peritoneal fluid lactate as a marker of intestinal ischaemia in equine colic

Use of multiple admission variables better predicts intestinal strangulation in horses with colic than peritoneal or the ratio of peritoneal:blood l-lactate concentration

BACKGROUND

Early identification of strangulating obstruction (SO) in horses with colic improves outcomes, yet early diagnosis of horses requiring surgery for SO often remains challenging.

OBJECTIVES

To compare blood and peritoneal fluid l-lactate concentrations, peritoneal:blood l-lactate ratio, peritoneal minus blood (peritoneal-blood) l-lactate concentration and other clinical variables for predicting SO and SO in horses with small intestinal lesions (SO-SI) and then to develop a multivariable model to predict SO and SO-SI.

STUDY DESIGN

Retrospective cohort.

METHODS

A total of 197 equids admitted to a referral institution for colic between 2016 and 2019 that had peritoneal fluid analysis performed at admission were included. Twenty-three admission variables were evaluated individually for the prediction of a SO or SO-SI and then using multivariable logistic regression. Odds ratios (ORs) with 95% confidence intervals (CI) and area under the curve of the receiver operator characteristic (AUC ROC) were calculated.

RESULTS

All variables performed better in the model than individually. The final multivariable model for predicting SO included marked abdominal pain (OR 5.31, CI 1.40-20.18), rectal temperature (OR 0.30, CI 0.14-0.64), serosanguineous peritoneal fluid (OR 35.34, CI 10.10-122.94), peritoneal-blood l-lactate (OR 1.77, CI 1.25-2.51), and peritoneal:blood l-lactate ratio (OR 0.36, CI 0.18-0.72). The AUC ROC was 0.91. The final multivariable model for predicting SO-SI included reflux volume (OR 0.69, CI 0.56-0.86), blood l-lactate concentration (OR 0.43, CI 0.22-0.87), serosanguineous peritoneal fluid (OR 4.99, CI 1.26-19.74), and peritoneal l-lactate concentration (OR 3.77, CI 1.82-7.81).

MAIN LIMITATIONS

Retrospective, single-hospital study design.

CONCLUSIONS

Blood and peritoneal fluid l-lactate concentrations should be interpreted in conjunction with other clinical variables. The relationship between peritoneal and blood l-lactate concentration for predicting SO or SO-SI was complex when included in a multivariable model. Models to predict SO probably vary based on lesion location.

Evaluation of peritoneal l-lactate concentration in horses in the early post-partum period

BACKGROUND

Peritoneal fluid lactate concentration is an important diagnostic tool in horses with abdominal pain. Information on peritoneal lactate concentrations is lacking following parturition in the mare.

OBJECTIVES

To compare blood and peritoneal lactate concentrations in a population of mares within 36 h post-partum, report a normal reference range and identify any impact of retained foetal membranes (RFMs).

METHODS

This is a retrospective study evaluating healthy mares from which blood and peritoneal samples had been obtained within 36 h of parturition. Exclusion criteria included signs of abdominal pain within this period. Data was interrogated for normality using a Shapiro-Wilk test. Wilcoxon signed-rank test and Bland-Altman analysis were used to compare blood and peritoneal lactate concentrations. Linear regression was used to compare age and breed data with peritoneal lactate concentrations. Significance was defined as p < 0.05.

RESULTS

Forty mares met the inclusion criteria. Mean age was 12.6 ± 4.1 years, and most mares were multiparous (65%). Peritoneal lactate ((1.2 (IQR = 0.9-1.6) mmol/L) was increased compared to blood lactate concentration (0.7 (IQR = 0-1.1)mmol/L; p < 0.001). Plasma total protein (TP) concentrations were 68 (IQR = 64-74) g/L and peritoneal protein concentrations 8 (IQR = 4-9.7) g/L. Six mares developed RFM. The median fold-increase in peritoneal lactate concentration compared to blood lactate concentration was 0.9 (IQR: 0.01-1.7; range: 0-2.5). The reference range for peritoneal fluid lactate concentration was 0-2.5 mmol/L.

CONCLUSION

Peritoneal lactate concentrations in healthy post-partum mares remained within the normal reference range and were not influenced by RFM or parturition. Increased peritoneal lactate in this group warrants further investigation.

Early Identification of Intestinal Strangulation: Why It Is Important and How to Make an Early Diagnosis

Horses with colic caused by intestinal strangulation can have an excellent outcome with early surgical correction of the obstruction. The expense associated with surgery is typically less with early lesion correction. The challenge is making an early diagnosis of intestinal strangulation. Although for some horses with a strangulating obstruction, the need for surgery is made based on severe colic signs or lack of response to analgesia, in other horses, it is less obvious. Signalment, history, and meticulous physical examination, combined with some targeted diagnostic procedures can help with early diagnosis of intestinal strangulation. Improving the outcome of these horses requires diligence and a team-based approach from the owner or caregiver, primary care veterinarian, and specialists.

Differentiating Strongylus vulgaris-associated, non-strangulating intestinal infarctions from idiopathic peritonitis and acute colitis in horses

BACKGROUND

Horses with non-strangulating intestinal infarction (NSII) are often misdiagnosed with idiopathic peritonitis or acute colitis. Early diagnosis is essential to ensure early surgical intervention and improve survival.

METHODS

Clinical and laboratory data from horses admitted to the University of Copenhagen Large Animal Teaching Hospital with NSII, idiopathic peritonitis or acute colitis between 2009 and 2018 were used for univariate comparisons and a multivariable logistic regression model for prediction of NSII.

RESULTS

Two hundred and thirty-one horses were included. A multivariable model for the prediction of NSII included gastric reflux (more than 5 L) (odds ratio [OR] 8.7; 95% confidence interval [CI] 2.1-36.2), abnormal findings palpated per rectum (intestinal dilatations/impactions [OR 4.43; 95% CI 1.43-13.38], colon displacements [OR 23.16; 95% CI 5.26-101.97] or intestinal mass [OR 179.7; 95% CI 23.5-1375.5]), white blood cell count (OR 1.2; 95% CI 1.1-1.4), packed cell volume (OR 0.9; 95% CI 0.8-0.9), age (OR 0.9; 95% CI 0.8-1.0) and heart rate (OR 1.1; 95% CI 1.0-1.1). The model had a low false positive rate (5%), but a high false negative rate (50%).

LIMITATIONS

Due to the retrospective nature of the study, sample collection was inconsistent, resulting in missing values.

CONCLUSION

The model had some capability in predicting NSII. However, the high risk of false negatives means that exploratory laparotomy should be considered in horses with peritonitis of unknown aetiology in areas where Strongylus vulgaris is prevalent and occurrence of idiopathic peritonitis is low.

Biomarkers of Intestinal Injury in Colic

Biomarkers are typically proteins, enzymes, or other molecular changes that are elevated or decreased in body fluids during the course of inflammation or disease. Biomarkers pose an extremely attractive tool for establishing diagnoses and prognoses of equine gastrointestinal colic, one of the most prevalent causes of morbidity and mortality in horses. This topic has received increasing attention because early diagnosis of some forms of severe colic, such as intestinal ischemia, would create opportunities for rapid interventions that would likely improve case outcomes. This review explores biomarkers currently used in equine medicine for colic, including acute phase proteins, proinflammatory cytokines, markers of endotoxemia, and tissue injury metabolites. To date, no single biomarker has been identified that is perfectly sensitive and specific for intestinal ischemia; however, L-lactate has been proven to be a very functional and highly utilized diagnostic tool. However, further exploration of other biomarkers discussed in this review may provide the key to accelerated identification, intervention, and better outcomes for horses suffering from severe colic.

Evaluation of Eosinopenia as a SIRS Biomarker in Critically Ill Horses

Systemic inflammatory response syndrome (SIRS) is a very common finding in critically ill patients. To accurately identify patients with SIRS and those who need intensive care, several markers have been evaluated, including cortisol, WBC or lactate. It is widely known that a stress leukogram includes eosinopenia as one of its main markers (neutrophilia, eosinopenia, lymphopenia and mild monocytes). It is known that cortisol concentration in plasma is the main stress biomarker and is strongly correlated with the severity of disease in horses. However, it is not possible to measure this parameter routinely in clinical conditions. Hence, in this study it was hypothesized that the eosinophil count could be a reliable parameter to identify critically ill horses. Horses included in this study were divided into three groups: Group A (sick horses received at the Emergency Unit which did not fulfil the criteria for SIRS), Group B (horses that meet two or more criteria for inclusion in the definition of SIRS) and a control group of healthy horses. In this study, horses with SIRS showed lower eosinophil counts than healthy horses. Moreover, non-surviving horses exhibited lower eosinophil counts than survivors. Eosinopenia could be used to identify horses with SIRS and can be useful as a prognostic marker.

Short-term survival rates of 1397 horses referred for colic from 2010 to 2018

Background

Up-to-date and hospital-specific knowledge of prognoses for horses with various forms of colic is essential for helping to guide owners’ decisions on costly treatments, and for assessing the continuous development of standards of care in the hospital. This study aimed to determine the short-term survival rates of horses admitted with colic to the University Hospital for Large Animals (UHLA), University of Copenhagen, Denmark, from 2010 to 2018, and to compare these to a previous local study as well as recent, comparable international studies.

Short-term survival rates were calculated for horses grouped by treatment (surgical, medical) and diseases. Results were compared to the selected studies using Chi-square tests.

Results

A total of 1752 horses were admitted with colic during the period, of which 355 were excluded for reasons such as economic restrictions or immediate euthanasia. Short-term survival of the remaining 1397 cases was significantly higher (83.0% (95% CI 81.1–85.0%)) than a previous local study (76%) and a recent Dutch study (80%). Medical treatment was carried out in 77.1% of cases, and surgery in 22.9% of the cases. Short-term survival for medically (89.7%) and surgically (60.6%) treated horses was significantly higher in the present study compared to the previous study (87% and 42%, respectively), but was similar to that found in the Dutch study. Significantly fewer horses were euthanised during surgery than in the previous study (17.2 vs. 40%), and significantly more horses recovered from surgery (79.1 vs. 56%). Short-term survival rate of surgically treated horses (60.6%) did not differ from other European studies (55–62%).

Conclusions

Short-term survival rates have increased since the previous study at UHLA, mainly due to a decrease in intraoperative euthanasia. Survival rates in this study are similar to those found in recent comparable colic studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13028-022-00631-4.

Interpreting abdominal fluid in colic horses: Understanding and applying peritoneal fluid evidence

BACKGROUND

Interpreting changes in peritoneal fluid helps clinicians manage colic and other diseases in horses. During abdominal problems in the horse, abdominal fluid characteristics such as color, turbidity, total nucleated and red blood cell counts, cytology, total protein, and l-lactate change in predictable ways, helping the clinician characterize the disease.

DESCRIPTION

Normal abdominal fluid in horses is odorless, clear to light yellow in color, and transparent. Peritoneal fluid becomes more turbid with increasing levels of protein, number of WBCs or RBCs, or with gross contamination following intestinal rupture. The color of abdominal fluid will also change with the type and quantity of cells or other elements present. The transformation of peritoneal fluid color from golden to orange to red represents increasing levels of RBCs, common with strangulating intestinal lesions. Serosanguinous defines fluid that is both turbid and orange to bloody because of increased total protein, WBCs, and RBCs, and is considered classic for diseases characterized by intestinal ischemia. Peritoneal fluid may also be red or blood-colored because of a hemoperitoneum, or secondary to blood contamination during sample collection. l-Lactate measurement in the abdominal fluid has proven invaluable for the identification of strangulating intestinal injury. Cytology acts as an important supplement to cell counts in peritoneal fluid, and the normal ratio of non-degenerate neutrophils:mononuclear cells of 2:1 changes during various gastrointestinal diseases. Culture of peritoneal fluid samples should be performed when septic peritonitis is suspected.

SUMMARY

Abdominal fluid is a sensitive indicator of intestinal injury and a useful tool to direct treatment. Peritoneal fluid evaluation includes gross visual and olfactory examination, nucleated cell count, total protein, RBC count, lactate levels, cytology, and culture. The changes noted in such variables are related to the type and duration of the abdominal problem.

KEY POINTS

 Abdominal fluid interpretation has become central to the triage and management of challenging equine colic patients.  The transformation of peritoneal fluid color from golden to orange to red represents increasing levels of RBCs, common with strangulating intestinal lesions.  Contamination with RBCs at various concentrations may be secondary to vascular (eg, abdominal wall or mesenteric vessels) or splenic trauma during abdominal fluid collection; however, this must be distinguished from orange to red fluid associated with intestinal strangulating obstruction or hemoabdomen  Peritoneal fluid analysis reveals abdominal pathology by recognizing specific changes that occur with disease processes affecting the tissues and organs within this cavity.  Abdominal fluid examination should be used as a tool to direct treatment rather than the definitive test for diagnosis of the acute abdomen  Septic peritonitis in horses most commonly originates secondary to intestinal compromise or accidents (vascular damage, perforation, or surgical manipulation), leading to bacterial translocation into the abdomen.

Abdominocentesis techniques in horses

BACKGROUND

Abdominocentesis is commonly used to evaluate the abdominal cavity of the horse. This technique provides valuable diagnostic information as well as the means to monitor patients with abdominal diseases being managed medically and to determine their need for surgical management. Complications are uncommon and include trauma to the gastrointestinal tract or spleen, septic peritonitis, or abdominal wall infection.

PROCEDURES

This review describes the indications, utility, patient preparation, and instructions for performing abdominocentesis as well as possible complications reported in horses. Step-by-step instructions are provided for the two most commonly used abdominocentesis techniques in horses, which include the use of a needle (18 Ga, 3.8 cm [1.5 in]) and a teat cannula (9.5 cm [3.75 in]).

SUMMARY

Peritoneal fluid collection and fluid analysis can be used to confirm diagnosis of intraabdominal pathology including inflammatory, infectious, neoplastic, obstructive, and bowel strangulation, leading to additional diagnostic and therapeutic plans.

KEY POINTS

Abdominocentesis is useful as a diagnostic procedure in horses suffering from colic, diarrhea, weight loss, or other conditions involving the abdominal cavity and is an integral component of diagnostic testing for colic at referral institutions or in the field. Abdominal fluid collection using an 18-Ga, 3.8-cm (1.5-in) needle is recommended for adult horses because the needle is long enough to penetrate the peritoneal cavity. The teat cannula technique is recommended for use in adult horses, foals, and miniature horses to reduce the risk of enterocentesis, even though this procedure is more traumatic than using an 18-Ga, 3.8-cm needle. Ultrasonography of the abdomen is a valuable tool in the assessment of any horse with signs of colic, but it is not essential for performing an abdominocentesis successfully.

Peritoneal fluid analysis in equine post-partum emergencies admitted to a referral hospital: A retrospective study of 110 cases

BACKGROUND

Peritoneal fluid analysis has both diagnostic and prognostic value in colic but is little reported in the post-partum mare. Multiple conditions may present similarly in this period, and peritoneal fluid findings may aid a prompt diagnosis.

OBJECTIVES

To describe the peritoneal fluid findings and their association with diagnosis in mares presenting to a single referral hospital for treatment of postpartum emergencies.

STUDY DESIGN

Retrospective clinical study.

METHODS

Clinical records of 110 Thoroughbred mares were reviewed. Details of peritoneal fluid analysis from samples obtained at admission were recorded, in addition to history, physical examination, presenting clinicopathological data. Cases were classified by their primary diagnosis into groups of gastrointestinal tract (GIT), urogenital trauma (UGT) and post parturient haemorrhage (PPH). Univariable analysis was performed to compare findings between groups, using one-way ANOVA and post hoc Tukey/Kruskal Wallis, as appropriate. Multinomial logistic regression was performed for variables significant in the univariable analysis.

RESULTS

When separated into their diagnostic categories, 33/110 (30%) mares were classified as GIT, 55/110 (50%) UGT and 22/110 (20%) PPH. Peritoneal fluid packed cell volume (PCV), nucleated cell count (WBCC) and cytological findings were significantly different between diagnostic categories. The likelihood of diagnosis of PPH increased with an increase in peritoneal fluid PCV, the absence of degenerate neutrophils on peritoneal fluid cytology and a decrease in the peritoneal fluid WBCC. Overall survival to discharge was 55%.

MAIN LIMITATIONS

Referral hospital-based study and retrospective nature. Missing data reduced power of analysis for several variables.

CONCLUSIONS

Peritoneal fluid analysis may guide diagnosis in postpartum emergencies, but no one factor is uniformly diagnostic. Mares with PPH presented with a non-septic peritonitis with higher peritoneal PCV.

Peritoneal bile acids concentration in adult horses with hepatic and gastrointestinal disorders

BACKGROUND

Peritoneal bile acids concentration (PBAC) has not been previously reported in horses. A case of liver lobe torsion in which increased PBAC was detected prompted us to study PBAC in horses.

OBJECTIVES

(a) To determine a reference range of PBAC in horses; (b) to compare PBAC from horses with either hepatic or gastrointestinal disease and healthy horses and (c) to assess the prognostic and diagnostic values of PBAC.

STUDY DESIGN

Prospective case-control.

METHODS

Prospective observational clinical study. Bile acids concentrations were measured in both plasma and peritoneal fluid in selected clinical patients with hepatic or gastrointestinal disease (n = 108) and healthy horses (n = 11). Sixty-eight of 108 patients survived to hospital discharge, and the remaining 40 were nonsurvivors. Additionally, other haematological and biochemistry analyses were performed.

RESULTS

Sick horses were classified according to diagnosis into hepatic (n = 13), gastrointestinal (GI) obstructive (n = 48) and GI ischaemic-inflammatory (n = 47) groups. The hepatic group had significantly higher PBAC (6.8 [2.3-9.4]; median [IQR]) than the control (1.0 [0.6-1.5]) and GI obstructive groups (1.2 [0.8-1.7] µmol/L; P < .001). Moreover, the GI ischaemic-inflammatory group (3.3 [1.4-5.5]) also had significantly higher values than the control and GI obstructive groups (P < .001). Regarding outcome, the nonsurvivor group (n = 40) had significantly higher median PBAC value than the survivor group (n = 68, 4.1 [1.6-6.5] vs 1.3 [0.8-3]; P < .001).

MAIN LIMITATIONS

A higher number of horses with abdominal disease is required to confirm the clinical significance of these findings.

CONCLUSIONS

PBAC may have a role in the diagnosis of hepatic and gastrointestinal disease and as a prognostic tool in horses with abdominal pain.

Development of a Colic Scoring System to Predict Outcome in Horses

Acute abdominal pain in the horse is a common emergency presenting to equine practices. The wide variety of etiologies makes prognosticating survival a challenge. A retrospective, multi-institutional clinical study was performed to determine clinical parameters associated with survival of horses with colic, and to use them to develop a colic survival scoring system. The scoring system was then validated using clinical data in the prospective portion of the study. Medical records from 67 horses presenting for acute abdominal pain were evaluated to develop the colic assessment score. Twenty eight variables were compared between survivors and non-survivors and entered into logistic regression models for survival. Of these, six variables were included in the colic assessment score. A total colic assessment score range was from 0 to 12, with the highest score representing the lowest probability of survival. The optimal cutoff value to predict survival was seven resulting in an 86% sensitivity and 64% specificity with a positive predictive value of 88% and a negative predictive value of 57%. Data from 95 horses presenting for abdominal pain to two equine hospitals was then collected prospectively to validate the colic assessment score. Horses from the prospective portion of the study that received a score >7 were classified as predicted to die and those with a score ≤7 were predicted to survive. The classification was compared to the actual outcome, of which the sensitivity, specificity, positive and negative predictive values of the colic assessment score were 84, 62, 88, and 52%, respectively.

Management of Colic in the Field

Colic is one of the most frequent emergencies necessitating veterinary attention. Referral is not an option in many cases; therefore, the ability to diagnose and treat colic in an ambulatory setting is paramount. Portable imaging and point-of-care testing has improved the ability to identify lesions and assess the patient's status. In cases when field management is the only option, practitioners should be aware of the various treatment options available.

Fluid Analysis in the Equine Patient: Cerebrospinal, Synovial, and Peritoneal Fluids

Fluid analysis is an important part of the diagnostic work-up of equine patients presenting with disorders of the nervous system, musculoskeletal system, and abdominal cavity. Proper specimen handling and processing are paramount for complete and accurate interpretation of fluid samples. Normal cerebrospinal fluid is a low-cellularity, low-protein fluid requiring specific sample handling to ensure accurate results. Joint and abdominal fluid analyses are completed in practice or submitted for analysis to a reference laboratory. This article discusses fluid sample handling and processing considerations for the equine practitioner and reviews cytologic evaluation of normal and abnormal cerebrospinal, synovial, and peritoneal fluid samples.

Variations in haematological and biochemical parameters in healthy ponies

Background

Breed specific reference ranges for selected blood parameters are recommended for proper interpretation of blood tests, but there are only few reports dealing with ponies. The purpose of this study was to investigate if blood parameters differ among ponies’ classes and to check if general normal values for equine species are applicable to ponies.

Results

All, except total protein concentration, biochemical parameter significantly (p < 0.05) differed among ponies’ classes. The most pronounced difference was noted in blood lactate concentrations, higher (p < 0.001) in the smallest ponies (class A). In all groups of ponies muscle enzymes (aspartate aminotransferase and creatine kinase) and urea were high when compared to normal values for equine species, but triglycerides and creatinine were low. Blood lactate concentration was high in comparison with normal values for horses only in class A ponies’.

Conclusions

In healthy ponies, blood lactate concentration significantly differs between height classes. Normal values for equine species should not be directly applied to interpret the lactate, triglycerides, aspartate aminotransferase and creatine kinase values in ponies.

MMP-9 Concentration in Peritoneal Fluid Is a Valuable Biomarker Associated with Endotoxemia in Equine Colic

The purpose of the study was to compare the results of sepsis scoring (clinical examination and clinical pathology) to the concentrations of matrix-metalloproteinases (MMPs) -2, -8, and -9; tissue-inhibitor of metalloproteinases (TIMPs) -1 and -2; and inflammatory chemokines interleukin (IL) 1β and tumor-necrosis-factor-alpha (TNF-α) in plasma and peritoneal fluid of equine colic patients. A modified sepsis scoring including general condition, heart and respiratory rate, rectal temperature, mucous membranes, white blood cell count (WBC), and ionized calcium was applied in 47 horses presented with clinical signs of colic. Using this scoring system, horses were classified as negative (n = 32, ≤6/19 points), questionable (n = 9, 7-9/19 points), or positive (n = 6, ≥10/19 points) for sepsis. MMPs, TIMPs, IL-1β, and TNF-α concentrations were evaluated in plasma and peritoneal fluid using species-specific sandwich ELISA kits. In a linear discriminant analysis, all parameters of sepsis scoring apart from calcium separated well between sepsis severity groups (P < 0.05). MMP-9 was the only biomarker of high diagnostic value, while all others remained insignificant. A significant influence of overall sepsis scoring on MMP-9 was found for peritoneal fluid (P = 0.005) with a regression coefficient of 0.092, while no association was found for plasma (P = 0.085). Using a MMP-9 concentration of >113 ng/ml in the peritoneal fluid was found to be the ideal cutoff to identify positive sepsis scoring (≥10/19 points; sensitivity of 83.3% and specificity of 82.9%). In conclusion, MMP-9 was found to be a biomarker of high diagnostic value for sepsis and endotoxemia in equine colic. The evaluation of peritoneal fluid seems preferable in comparison to plasma. As abdominocentesis is commonly performed in the diagnostic work-up of equine colic, a pen-side assay would be useful and easy-to-perform diagnostic support in the decision for therapeutic intervention.

Diagnostic value of plasma and peritoneal fluid procalcitonin concentrations in horses with strangulating intestinal lesions

OBJECTIVE

To assess the diagnostic value of plasma and peritoneal fluid procalcitonin concentrations for identification of horses with strangulating intestinal lesions.

ANIMALS

65 horses with signs of colic of intestinal origin and 10 healthy (control) horses.

PROCEDURES

For each horse, plasma and peritoneal fluid samples were obtained for a CBC and determination of total protein, procalcitonin, and lactate concentrations. Signalment and clinicopathologic findings were compared among control horses and horses with strangulating and nonstrangulating intestinal lesions.

RESULTS

Mean ± SD plasma (274.9 ± 150.8 pg/mL) and peritoneal fluid (277 ± 50.6 pg/mL) procalcitonin concentrations for horses with colic were significantly greater than the mean ± SD plasma (175.5 ± 46.0 pg/mL) and peritoneal fluid (218.8 ± 48.7 pg/mL) procalcitonin concentrations for control horses. Mean procalcitonin concentration in peritoneal fluid, but not plasma, differed significantly between horses with strangulating lesions and those with nonstrangulating lesions. A peritoneal fluid procalcitonin concentration ≥ 281.7 pg/mL had a sensitivity of 81%, specificity of 69%, positive predictive value of 56.7%, and negative predictive value of 87.9% for detection of strangulating lesions.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that peritoneal fluid procalcitonin concentration, when evaluated in conjunction with other clinicopathologic results, might be a sensitive indicator of intestinal ischemia and facilitate early identification of horses that require surgery to address a strangulating lesion.

Prognostic value of colonic and peripheral venous lactate measurements in horses with large colon volvulus

OBJECTIVE

To determine the prognostic value of (1) colonic venous lactate or peripheral lactate values obtained before and after manual correction of a large colon volvulus and (2) a combination of variables including pelvic flexure biopsy.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Forty adult horses in which large colon volvulus was diagnosed intraoperatively.

METHODS

Colonic venous, peripheral venous, and arterial blood samples were collected to measure lactate values before and after manual correction. Mucosal biopsy samples were obtained in cases that underwent enterotomy or colonic resection and anastomosis. Interstitium to crypt (I:C) ratio and hemorrhage scores were measured. Optimal cutoff values were determined by receiver operator curve analysis, and associations between variables and short-term outcome were determined by univariable regression. Short-term survival was defined as horses being discharged from the hospital. P ≤ .05 was considered significant.

RESULTS

No association was found between colonic venous lactate values before (P = .011) or after (P = .201) manual correction of large colon volvulus and determination of short-term outcome. Peripheral venous lactate at admission ≥3.2 mmol/L and after manual correction ≥5 mmol/L, arterial lactate postmanual correction ≥3.53 mmol/L, and histomorphometric measurements of mucosal hemorrhage ≥3 and I:C ratio > 1 were associated with poor short-term outcome.

CONCLUSION

Peripheral lactate values, histomorphometric measures of I:C ratio, and hemorrhage score provided prognostic information that could help guide recommendations made to owners.

CLINICAL SIGNIFICANCE

Peripheral lactate values after manual correction provide important intraoperative diagnostic information to assist in predicting case outcome in the operative and immediately postoperative period.

Reduced Gut Microbiome Diversity and Metabolome Differences in Rhinoceros Species at Risk for Iron Overload Disorder

Iron overload disorder (IOD) affects many wildlife species cared for ex situ. Two of the four rhinoceros species in human care, Sumatran rhinoceros (Dicerorhinus sumatrensis) and black rhinoceros (Diceros bicornis), are susceptible, whereas the other two, white rhinoceros (Ceratotherium simum) and greater one-horned (GOH) rhinoceros (Rhinoceros unicornis), are relatively resistant to IOD. Complex interrelationships exist between mammalian hosts, their indigenous gut microbiota, metabolome, physical condition, and iron availability. The goal of this study was to gain insight into these relationships within the family Rhinocerotidae. Specific objectives were to (1) characterize the gut microbiome and metabolome of four rhinoceros species; (2) compare the microbiome and metabolome of IOD-susceptible and IOD-resistant rhinoceros species; and (3) identify variation in the microbiome and metabolome associated with compromised health or disease in IOD-susceptible rhinoceroses. Fecal samples were collected from 31 rhinoceroses (Sumatran rhinoceros, n = 3; black rhinoceros, n = 6; GOH rhinoceros, n = 9; white rhinoceros, n = 13) located at five facilities, and matched fecal aliquots were processed for microbiome and metabolome analyses using 16S rRNA gene sequencing and nuclear magnetic resonance spectroscopy, respectively. Despite the phylogenetic disparity and dissimilar zoo diets of the hosts, the structure of the fecal microbiota of the two IOD-susceptible rhinoceros species were more closely related to each other than to those of the two IOD-resistant species (Bray–Curtis dissimilarity; IOD-susceptible vs. IOD-resistant p-value < 0.001). In addition, IOD-susceptible rhinoceroses exhibited less microbial diversity than their IOD-resistant relatives (Shannon diversity; p-value < 0.001) which could have health implications. Of note, the black rhinoceros was distinct among the four rhinoceros species with the most divergent fecal metabolome; interestingly, it contained higher concentrations of short chain fatty acids. Neither age nor sex were associated with differences in microbial community composition (p = 0.253 and 0.488, respectively) or fecal metabolomic profile (p = 0.634 and 0.332, respectively). Differences in the distal gut microbiomes between IOD-resistant and IOD-susceptible rhinoceroses support hypotheses that gut microbes play a role in host iron acquisition, and further studies and experiments to test these hypotheses are warranted.

Preoperative factors associated with resection and anastomosis in horses presenting with strangulating lesions of the small intestine

OBJECTIVE

To determine if preoperative and intraoperative clinical variables correlate with resection and anastomosis (RA) in horses presenting with strangulating small intestinal (SI) lesions.

STUDY DESIGN

Retrospective case series.

ANIMALS

Horses undergoing exploratory celiotomy for a strangulating SI lesion (n = 243).

METHODS

The records of horses undergoing surgical correction for strangulating SI lesions from January 1, 2000 to December 31, 2017 were reviewed. Horses were categorized as treated with RA or not treated with RA. Obtained information included history, signalment, clinical findings, diagnostic test results, intraoperative findings, and survival to discharge. Univariable and multivariable analyses were used to compare data between horses treated with RA vs those not treated with RA (P = .05).

RESULTS

In total, 172 SI lesions were resected, and 71 were not resected. Horses that had gastric reflux at admission to the hospital (odds ratio [OR] 5.56; 95% CI 1.76, 17.59) and horses with amotile SI according to abdominal ultrasonography (OR 9.69; 95% CI 3.09, 30.37) were more likely to undergo RA. Increased difference between peritoneal fluid and blood lactate was higher in horses that underwent RA (OR 1.55; 95% CI 1.12, 2.13). Survival to hospital discharge was lower in the group of horses that underwent RA compared with horses that did not undergo RA.

CONCLUSION

Resection and anastomosis of strangulating SI lesions was associated with several preoperative variables.

CLINICAL SIGNIFICANCE

This study highlights the value of preoperative diagnostic procedures in aiding intraoperative decision making and prognostication in horses presenting with strangulating SI lesions.

Exploratory Celiotomy in the Horse Secondary to Acute Colic: A Review of Indications and Success Rates

To review indications and risk factors for exploratory celiotomy secondary to acute colic in the horse; decision making for and during surgery; and prognosis for return to function after exploratory celiotomy for the practicing veterinarian. Data sources included scientific reviews and original research publications from veterinary sources, as well as clinical data specifically in regard to underlying disease and survival rates from a tertiary referral hospital where exploratory celiotomy is commonly performed. There is a high positive predictive value of specific clinical preoperative parameters of the equine acute abdomen, many of which rely on techniques available to field practitioners, relative to the need for surgical intervention. Decision making regarding surgical procedure or even intraoperative euthanasia depends on owner expectations. Survival rates following exploratory celiotomy range from fair to excellent (60%-100%) depending on underlying lesion and return to athleticism following celiotomy is good to excellent (76%-90%). A knowledge base of indications for and rates of survival from colic requiring exploratory celiotomy in the horse is of paramount importance to the equine practitioner. Preconceived notions of poor survival rates are rampant among horse owners, and owners rely on their primary veterinarian's advice for continuation to referral center and in further treatment including exploratory celiotomy.

Small intestinal herniation through the broad ligament in a mare outside of the gestation period – a case report

A Furioso-North Star mare, aged 8 years, was examined for colic signs. The mare had a history of dystocia and post partum vaginal lacerations, acute endometritis and laminitis approximately one year before the admission for colic. Signs of persistent abdominal pain, moderate distended abdomen, non-passage of manure, fever, tachycardia, tachypnoea, congested mucus membranes, and “toxic line” were recorded. No intestinal borborygmi were present in the four quarters of the abdomen. On rectal examination, the colon, the ventral band of the caecum, the right ovary and the uterine horn were palpated on the right side of the abdomen. The spleen, the nephrosplenic ligament, the left ovary and a firm, distended and painful small intestine (SI) loop were palpated on the left side. The left uterine horn and the adjacent broad ligament were not detectable. Percutaneous abdominal ultrasound evaluation revealed a large amount of fluid in the abdominal cavity, SI distention and absence of peristalsis. Abdominocentesis yielded approximately 20 ml of red-tinged peritoneal fluid with increased mean protein concentration (5.2 mg/dl), white blood cell count (12,550 cells/μl), and lactate (14 mmol/dl). A presumptive diagnosis of SI strangulation was made. Surgical resection of the affected intestinal loops was recommended. Due to poor prognosis and financial limitations, the mare was euthanized. Post mortem macroscopic diagnosis was a herniation of 3 metres of the mid-jejunum through the left mesometrium, resulting in a complete and complicated strangulation. To prevent this type of SI strangulation, we recommend transrectal palpation of the urogenital tract (including the broad ligament) after foaling. If a defect is identified, we recommend flank laparoscopy for correction.

Predictive value of plasma and peritoneal creatine kinase in horses with strangulating intestinal lesions

OBJECTIVE

To determine the ability of plasma and peritoneal creatine kinase (CK) to predict the presence of a strangulating lesion in horses presented for colic.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Ten healthy control horses and 61 clinical colic cases.

METHODS

Creatine kinase activity was measured in peritoneal fluid and plasma of 10 healthy horses and 61 horses presenting for colic (40 horses with nonstrangulating lesions and 21 horses with strangulating lesions). Information on other blood and peritoneal fluid variables, signalment, results from the physical examination, outcome, requirement for surgery, and lesion location and type were retrieved from the medical records of horses presenting for colic.

RESULTS

A peritoneal CK cutoff level of 16 IU/L yielded a sensitivity of 95.2% and a specificity of 84.6% (positive predictive value [PPV] = 76.9% and negative predictive value [NPV] = 97%, respectively) for predicting a strangulating lesion. A peritoneal lactate cutoff level of 3.75 mmol/L yielded a sensitivity of 81% and a specificity of 92% (PPV = 85% and NPV = 90%, respectively) for predicting a strangulating lesion.

CONCLUSION

Peritoneal CK concentration was a sensitive indicator of the presence of a strangulating lesion in horses presenting with colic, whereas peritoneal lactate concentration was a more specific indicator.

CLINICAL SIGNIFICANCE

Measuring CK in peritoneal fluid may be a useful adjunct to clinical case presentation to accelerate the diagnosis and definitive treatment of horses presenting with strangulating intestinal lesions, thereby improving their outcome.

Clinical use of plasma lactate concentration. Part 2: Prognostic and diagnostic utility and the clinical management of hyperlactatemia

OBJECTIVE

To review the current literature pertaining to the use of lactate as a prognostic indicator and therapeutic guide, the utility of measuring lactate concentrations in body fluids other than blood or plasma, and the clinical management of hyperlactatemia in dogs, cats, and horses.

DATA SOURCES

Articles were retrieved without date restrictions primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Increased plasma lactate concentrations are associated with increased morbidity and mortality. In populations with high mortality, hyperlactatemia is moderately predictive in identifying nonsurvivors. Importantly, eulactatemia predicts survival better than hyperlactatemia predicts death. Consecutive lactate measurements and calculated relative measures appear to outperform single measurements. The use of lactate as a therapeutic guide has shown promising results in people but is relatively uninvestigated in veterinary species. Increased lactate concentrations in body fluids other than blood should raise the index of suspicion for septic or malignant processes. Management of hyperlactatemia should target the underlying cause.

CONCLUSION

Lactate is a valuable triage and risk stratification tool that can be used to separate patients into higher and lower risk categories. The utility of lactate concentration as a therapeutic target and the measurement of lactate in body fluids shows promise but requires further research.

Investigation of perioperative and anesthetic variables affecting short-term survival of horses with small intestinal strangulating lesions

OBJECTIVE

To determine if preoperative and intraoperative physiologic variables, and surgical factors correlate with survival to anesthetic recovery or hospital discharge, repeat celiotomy, and postoperative nasogastric intubation (NGT) in horses undergoing exploratory celiotomy for small intestinal (SI) strangulating lesions.

STUDY DESIGN

Retrospective case series.

ANIMALS

Horses that had surgical correction of SI strangulating lesions (n = 258).

METHODS

Medical records (January 2000-December 2014) of horses that had surgical correction of SI strangulating lesions were reviewed. Data collection included signalment, preoperative physical examination variables, hematologic values, presence of gastric reflux, peritoneal fluid analysis, intraoperative physiologic variables, intraoperative findings/treatments, and arterial blood gas values. Risk factors for survival to anesthetic recovery and hospital discharge were determined using exact logistic regression.

RESULTS

Survival to anesthetic recovery was 76% and survival to discharge after anesthetic recovery was 79%. The difference between abdominal and peripheral lactate concentrations and intraoperative tachycardia were associated with not surviving to anesthetic recovery or hospital discharge. Intraoperative hypotension, hypocapnia, and low intraoperative packed cell volume (PCV) were negative predictors of survival to anesthetic recovery. Low intraoperative PCV was also associated with NGT postoperatively. Performing resection-anastomosis and jejunocecostomy were associated with repeat celiotomy and with not surviving to hospital discharge.

CONCLUSION

Several hematological and cardiorespiratory variables show good correlation with short-term survival in horses undergoing surgery for SI strangulating lesions. These variables are easily measured and could be useful for prognosticating survival in horses presenting with SI strangulating lesions.

GPR4 deficiency alleviates intestinal inflammation in a mouse model of acute experimental colitis

GPR4 is a proton-sensing G protein-coupled receptor that can be activated by extracellular acidosis. It has recently been demonstrated that activation of GPR4 by acidosis increases the expression of numerous inflammatory and stress response genes in vascular endothelial cells (ECs) and also augments EC-leukocyte adhesion. Inhibition of GPR4 by siRNA or small molecule inhibitors reduces endothelial cell inflammation. As acidotic tissue microenvironments exist in many types of inflammatory disorders, including inflammatory bowel disease (IBD), we examined the role of GPR4 in intestinal inflammation using a dextran sulfate sodium (DSS)-induced acute colitis mouse model. We observed that GPR4 mRNA expression was increased in mouse and human IBD tissues when compared to control intestinal tissues. To determine the function of GPR4 in intestinal inflammation, wild-type and GPR4-deficient mice were treated with 3% DSS for 7days to induce acute colitis. Our results showed that the severity of colitis was decreased in GPR4-deficient DSS-treated mice in comparison to wild-type DSS-treated mice. Clinical parameters, macroscopic disease indicators, and histopathological features were less severe in the DSS-treated GPR4-deficient mice than the DSS-treated wild-type mice. Endothelial adhesion molecule expression, leukocyte infiltration, and isolated lymphoid follicle (ILF) formation were reduced in intestinal tissues of DSS-treated GPR4-null mice. Collectively, our results suggest GPR4 provides a pro-inflammatory role in the inflamed gut as the absence of GPR4 ameliorates intestinal inflammation in the acute experimental colitis mouse model.

Extracellular Acidification Acts as a Key Modulator of Neutrophil Apoptosis and Functions

In human pathological conditions, the acidification of local environment is a frequent feature, such as tumor and inflammation. As the pH of microenvironment alters, the functions of immune cells are about to change. It makes the extracellular acidification a key modulator of innate immunity. Here we detected the impact of extracellular acidification on neutrophil apoptosis and functions, including cell death, respiratory burst, migration and phagocytosis. As a result, we found that under the acid environment, neutrophil apoptosis delayed, respiratory burst inhibited, polarization augmented, chemotaxis differed, endocytosis enhanced and bacteria killing suppressed. These findings suggested that extracellular acidification acts as a key regulator of neutrophil apoptosis and functions.

Influence of disease process and duration on acute phase proteins in serum and peritoneal fluid of horses with colic

Background

The acute phase proteins (APP) serum amyloid A (SAA), haptoglobin, and fibrinogen are valuable blood biomarkers in equine inflammatory diseases, but knowledge of factors influencing their concentrations in blood and peritoneal fluid (PF) of horses with colic is needed.

Objectives

The objective of this study was to investigate the influence of demographics (age, sex, breed), disease process (simple obstruction, strangulating obstruction, inflammatory), disease location, disease duration, hypovolemia, and admission hospital on concentrations of APP, lactate and white blood cell counts (WBC) in horses with colic admitted to 2 referral hospitals.

Animals

The study included 367 horses with colic admitted at 2 referral hospitals.

Methods

Prospective multicenter observational study of clinical data, as well as blood and PF biomarkers. Associations between biomarker concentrations and clinical variables were analyzed using multivariate linear regression analysis.

Results

Increasing pre‐admission duration of colic was associated with increased concentrations of APP in blood and PF. Blood concentrations of SAA and fibrinogen were associated with disease process (inflammatory, strangulations, simple obstructions) in more colic duration groups (5–12 and >24 hours) than any of the other biomarkers. No relevant associations between demographic factors, hospital, or hydration status and the measured biomarkers were found.

Conclusions and Clinical Importance

In horses with colic, concentrations of APP are associated mainly with disease process and duration of colic and may thus be used for assessment of disease independently of demographic or geographic factors. Serum amyloid A may be a diagnostic marker for use in colic differential diagnosis, but further evaluation is needed.

The clinical value of whole blood point-of-care biomarkers in large animal emergency and critical care medicine

OBJECTIVE

To summarize the current medical literature and provide a clinical perspective of whole blood point-of-care (POC) biomarkers in large animal emergency and critical care practice.

DATA SOURCES

Original studies, reviews, and textbook chapters in the human and veterinary medical fields.

SUMMARY

POC biomarkers are tests used to monitor normal or disease processes at or near the patient. In both human and veterinary medicine these tools are playing an increasingly important role in the management of critical diseases. The most important whole blood POC biomarkers available for veterinary practitioners include l-lactate, cardiac troponin I, serum amyloid A, triglyceride, creatinine, and glucose, although many other tests are available or on the horizon.

CONCLUSION

Whole blood POC biomarkers enable clinicians to provide improved management of critical diseases in large animals. These tools are especially useful for establishing a diagnosis, guiding therapy, and estimating disease risk and prognosis.

Evaluation of 3 handheld portable analyzers for measurement of L-lactate concentrations in blood and peritoneal fluid of horses with colic

OBJECTIVE

To compare 3 portable handheld analyzers with a bench top blood gas analyzer for measurement of blood and peritoneal fluid L-lactate concentrations in horses admitted with signs of colic.

STUDY DESIGN

Prospective clinical study.

SAMPLE POPULATION

Blood and peritoneal fluid from horses with colic.

METHODS

L-lactate concentrations in heparinized blood and peritoneal fluid were measured serially on 10 occasions to evaluate repeatability of the portable analyzers. Blood and peritoneal fluid L-lactate concentrations were simultaneously evaluated by a bench top and 3 portable analyzers and the results compared by intraclass correlation coefficients and Bland Altman plots. L-Lactate concentrations in a subgroup of peritoneal fluid samples were evaluated by a chromogenic laboratory assay and compared with the bench top and the handheld analyzers.

RESULTS

Portable lactate analyzers had good intra-analyzer reliability for peritoneal fluid. Two portable analyzers had poor intra-analyzer reliability for mid concentrations of L-lactate in blood. L-lactate measurements from portable analyzers were closer to the bench top analyzer at low concentrations of L-lactate than at higher concentrations. Compared with the bench top analyzer, the Lactate Pro and Lactate Plus have the highest intraclass correlation coefficient and the smallest bias for peritoneal fluid and blood L-lactate, respectively. The bench top analyzer and the Lactate Pro had the highest level of agreement for peritoneal fluid compared with the chromogenic assay.

CONCLUSIONS

Although portable analyzers are alternatives for the measurement of L-lactate concentration in field situations, clinicians need to be aware of the variable results between analyzers, especially when extrapolating means or cutoff values from studies using different lactate analyzers.

Blood lactate measurement and interpretation in critically ill equine adults and neonates

Admission blood lactate concentration is widely used as a prognostic indicator in equine medicine and can be a useful indicator of disease severity but typically fails to completely discriminate survivors from nonsurvivors. Increased admission lactate concentrations in adult horses typically return to normal within 12 to 24 hours. Lactate concentrations in neonatal foals are higher than adult concentrations for the first 24 to 72 hours of life. Serial measures reflecting both the magnitude and duration of hyperlactatemia might enable more accurate prognostication and provide insight into disease pathogenesis and could be a valuable therapeutic guide.

Evaluation of the colic in horses: decision for referral

This article presents an overview of key factors that should alert the practitioner toward referral of a colic patient to a facility capable of surgical exploration or intensive medical management. Discussion includes a review of important aspects of colic history, signalment, physical examination findings, and diagnostic test results that indicate that a more serious medical or surgical condition exists, and advanced therapy is necessary.