Scoring System for Multiple Organ Dysfunction in Adult Horses with Acute Surgical Gastrointestinal Disease

Assessment and comparison of microcirculation and macrocirculation in horses undergoing emergency exploratory celiotomy versus elective surgical procedures

OBJECTIVE

To assess oral buccal microcirculation by hand-held videomicroscopy in horses during colic surgery, comparing microcirculation values with macrocirculatory parameters and with those of healthy elective surgical horses.

STUDY DESIGN

Clinical prospective study.

ANIMALS

Client-owned horses (nine in the colic group; 11 in the elective group).

METHODS

In the colic group, buccal mucosal side stream dark-field microscopy (DFM) videos, cardiac output (CO), mean arterial pressure (MAP), and lactate were obtained at three timepoints under general anesthesia (30, 90, and 150 min after induction). Video analysis was used to determine total vessel density, proportion of perfused vessels, perfused vessel density, and heterogeneity index. Dark-field microscopy videos, MAP, and lactate were obtained at a single timepoint under general anesthesia (45 min after induction) in the elective group.

RESULTS

There were no differences in microcirculatory parameters between colic and elective horses, nor was there a difference across timepoints in the colic group. There was a weak negative correlation between microvascular parameters and CO (rho = -0.23).

CONCLUSION

The colic group did not have decreased microcirculation in comparison with the healthy elective group. Dark-field microscopy did not correlate well with macrocirculatory parameters in the colic group.

IMPACT

Dark-field microscopy may not be a sensitive enough indicator to detect differences in microcirculation between colic and elective groups. The lack of difference in microcirculation may be due to sample size, probe location, or variation in disease severity.

Clinical predictive models in equine medicine: A systematic review

Clinical predictive models use a patient's baseline demographic and clinical data to make predictions about patient outcomes and have the potential to aid clinical decision making. The extent of equine clinical predictive models is unknown in the literature. Using PubMed and Google Scholar, we systematically reviewed the predictive models currently described for use in equine patients. Models were eligible for inclusion if they were published in a peer-reviewed article as a multivariable model used to predict a clinical/laboratory/imaging outcome in an individual horse or herd. The agreement of at least two authors was required for model inclusion. We summarised the patient populations, model development methods, performance metric reporting, validation efforts, and, using the Predictive model Risk of Bias Assessment Tool (PROBAST), assessed the risk of bias and applicability concerns for these models. In addition, we summarised the index conditions for which models were developed and provided detailed information on included models. A total of 90 predictive models and 9 external validation studies were included in the final systematic review. A plurality of models (41%) was developed to predict outcomes associated with colic, for example, need for surgery or survival to discharge. All included models were at high risk of bias, defined as failing one or more PROBAST signalling questions, primarily for analysis-related reasons. Importantly, a high risk of bias does not necessarily mean that models are unusable, but that they require more careful consideration prior to clinical use. Concerns about applicability were low for the majority of models. Systematic reviews such as this can serve to increase veterinarians' awareness of predictive models, including evaluation of their performance and their use in different patient populations.

Spontaneous Sepsis in Adult Horses: From Veterinary to Human Medicine Perspectives

Sepsis is a life-threatening disease defined as an organ dysfunction caused by a dysregulated host response to an infection. Early diagnosis and prognosis of sepsis are necessary for specific and timely treatment. However, no predictive biomarkers or therapeutic targets are available yet, mainly due to the lack of a pertinent model. A better understanding of the pathophysiological mechanisms associated with sepsis will allow for earlier and more appropriate management. For this purpose, experimental models of sepsis have been set up to decipher the progression and pathophysiology of human sepsis but also to identify new biomarkers or therapeutic targets. These experimental models, although imperfect, have mostly been performed on a murine model. However, due to the different pathophysiology of the species, the results obtained in these studies are difficult to transpose to humans. This underlines the importance of identifying pertinent situations to improve patient care. As humans, horses have the predisposition to develop sepsis spontaneously and may be a promising model for spontaneous sepsis. This review proposes to give first an overview of the different animal species used to model human sepsis, and, secondly, to focus on adult equine sepsis as a spontaneous model of sepsis and its potential implications for human and veterinary medicine.

Oral supplementation with Lithothamnion extract in horses subjected to oligofructose overload intake: effects on systemic inflammation and multiple organ function

Systemic inflammatory response syndrome (SIRS) is a common condition in horses with gastrointestinal disorders. If not prevented or controlled, SIRS promotes multiple organ dysfunctions that may culminate in serious disabilities or even death. The objective of this study was to evaluate the effects of Lithothamnion supplementation on systemic inflammatory response and organ function variables in horses undergoing oligofructose overload (OFO) intake. Twelve healthy horses were randomly divided into control and treated groups. The treated group received Lithothamnion (100 mg/kg bw PO BID) for 7 days before oligofructose intake (10 g/kg PO). Horses underwent clinical and laboratory evaluation immediately before and 6, 12, 18, and 24 h following administration of oligofructose. Parametric data were subjected to ANOVA in randomized blocks, followed by Tukey, and Student's t-tests for mean comparsions. Non-parametric data were analyzed by the Friedman, Dunn's, and Mann-Whitney tests (P < .05). Systemic inflammation and organ dysfunction was evident in both groups; however, these changes were milder and delayed in the treated group. Supplementation attenuated and delayed the tachycardia, tachypnea, leukocytosis, hyperproteinemia, hyperbilirubinemia, hyperalbuminemia and hyperglycemia in treated horses undergoing OFO. Furthermore, increases in packed cell volume, red blood cells, hemoglobin, globulin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, indirect and direct bilirubin and creatinine were observed only in the control group, remaining unchanged in the treated group. These findings demonstrate the potential of oral supplementation with Lithothamnion to ameliorate systemic inflammation and organ dysfunction in horses at risk of acquiring gastrointestinal disorders.

Performance of predictive models of survival in horses undergoing emergency exploratory laparotomy for colic

Objective

To evaluate previously published predictive survival models in a population of horses undergoing colic surgery in the midwestern United States.

Study design

Retrospective cohort study; single referral hospital.

Animals

A total of 260 horses met the inclusion criteria.

Methods

Medical records of horses undergoing surgical treatment for colic were reviewed. Previously published models were applied to cohort data to predict outcome. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for prediction of short‐term survival were calculated.

Results

Single‐variable and multivariable models performed similarly for prediction of survival, with a mean 79% sensitivity (range: 44%–94%), 48% specificity (range: 22%–83%), 63% PPV (range: 56%–72%), 73% NPV (range: 60%–83%), and 64% accuracy (range: 59%–72%). Blood lactate ≤6 mmol/l and the colic severity score (CSS) were highly sensitive for prediction of survival; however, both had poor specificity.

Conclusion

Single‐variable and multivariable predictive models did not perform as well for prediction of survival in the study cohort compared to original reports, suggesting that population‐specific factors contribute to patient survival.

Clinical significance

Predictive models of survival developed in one population may be less reliable when used to predict outcome in horses undergoing colic surgery from an independent population. Additional model testing and refinement using data from multiple surgical centers could be considered to improve prediction of outcome for horses undergoing laparotomy for treatment of colic.

Laminitis Updates: Sepsis/Systemic Inflammatory Response Syndrome-Associated Laminitis

Sepsis or systemic inflammatory response syndrome (SIRS) -associated laminitis is a sequela to primary inflammatory conditions (eg, colitis, ischemic intestinal injury, pneumonia, metritis) and results from a dysregulated systemic inflammatory response that ultimately affects the digital lamellae. Local chemokine production, leukocyte migration, and proinflammatory mediator production occur within the lamellae that can lead to catastrophic lamellar failure. Controlling the primary disease, providing supportive care and anti-inflammatory therapy, applying digital cryotherapy, and providing mechanical support are cornerstones to the prevention of sepsis/SIRS-associated laminitis. Novel therapies targeting specific signaling pathways may provide additional therapeutic options in the future.

Prognostic value of measuring heart rate variability at the time of hospital admission in horses with colic

OBJECTIVE

To evaluate the prognostic value of measuring heart rate variability (HRV) in horses with colic at the time of admission to a referral hospital.

ANIMALS

51 horses > 1 year of age with colic (41 that survived [survivors] and 10 that died or were euthanized [nonsurvivors]).

PROCEDURES

HRV was recorded within 1 hour after admission by use of heart rate sensors with horses restrained in stocks. A 5-minute recording period was analyzed to obtain HRV measurements (eg, SD of R-R intervals [SDRR], root mean square of successive differences between R-R intervals [RMSSD], and geometric SDs determined from Poincaré plots [SD1 and SD2]). Variables associated with outcome (survival vs nonsurvival) were identified. Measurements were compared among diagnostic categories for colic (obstructive, inflammatory, or ischemic).

RESULTS

SDRR and RMSSD were significantly higher in survivors (median [25th to 75th percentile], 91.0 milliseconds [78.9 to 114.6 milliseconds] and 64.8 milliseconds [40.9 to 78.4 milliseconds], respectively) than in nonsurvivors (50.7 milliseconds [29.1 to 69.2 milliseconds] and 33.4 milliseconds [12.6 to 47.9 milliseconds], respectively). Similarly, SD1 and SD2 were significantly higher in survivors (48.3 milliseconds [28.9 to 60.9 milliseconds] and 111.3 milliseconds [93.0 to 146.6 milliseconds], respectively) than in nonsurvivors (23.7 milliseconds [8.9 to 33.9 milliseconds] and 65.1 milliseconds [33.7 to 91.9 milliseconds], respectively). The SDRR and SD2 were significantly higher for horses with obstructive colic than for horses with ischemic colic.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of HRV in horses with colic may provide information on the underlying cause and be helpful in identifying horses less likely to survive.

Outcome of horses with enterocolitis receiving oncotic fluid support with either plasma or hetastarch

The objective of this study was to determine whether there was an association between type of colloid administered and survival of horses with enterocolitis (N = 92). A retrospective review of medical records of horses with enterocolitis treated with plasma or hetastarch (HES) between January 1, 2005 and December 31, 2011 was performed. Data collected included signalment, outcome, physical and clinicopathologic findings, and volume and type of colloid administered. Sixty-nine horses (75%) were treated with plasma and 23 horses (25%) were treated with HES. After accounting for confounding variables, horses treated with plasma (80% survival) were more likely to survive to discharge than horses treated with HES (47% survival; P = 0.041) despite similar disease severity at admission. This study provides support that use of natural colloids may be superior to treatment with synthetic colloids in horses with enterocolitis. A prospective, multi-center trial comparing outcome of critically ill equine patients treated with natural or synthetic colloids is warranted.

Clinical, hematologic, hemostatic, and serum biochemical findings related to survival in Arabian horses with colic

BACKGROUND

The efficacy of clinical examinations, and hematologic, hemostatic, and serum biochemical assessments to determine appropriate early medical or surgical therapy in Arabian horses with colic have not been well-described.

OBJECTIVES

We aimed to evaluate clinical and hematologic findings, coagulation-fibrinolytic parameters, and organ dysfunction markers in association with survival in horses with colic.

METHODS

Seventeen Arabian horses with colic and ten healthy horses were enrolled. After clinical examinations, including heart rates (HRs), capillary refill times (CRTs), abdominal sounds, rectal palpations, and nasogastric (NG) reflux assessments in both healthy and diseased horses, blood samples were collected and hematologic parameters, coagulation indices such as the prothrombin time (PT), activated partial thromboplastin time (APTT), plasma d-dimer (PDD), platelet count, fibrinogen, and hepatorenal biomarkers were measured. Based on the outcomes, horses with colic were divided into survival (10) and nonsurvival (7) groups, and all mentioned parameters were compared with the control group horses.

RESULTS

Unlike HRs, CRTs, and abdominal sounds, rectal palpations (57.1%) and NG reflux (28.6%) findings were least sensitive in being able to determine survival. At least three of the five coagulation indices were significantly abnormal (prolonged PT, increased PDD, and decreased plasma fibrinogen) in 71.4% of the horses in the nonsurvival group compared with the control and survival groups. Significantly increased urea, creatinine, and bilirubin levels, and AST activities were also observed in the survival group compared with the control and nonsurvival groups.

CONCLUSIONS

The combination of prolonged PT, increased PDD, and hypofibrinogenemia could be a reliable predictor of survival in horses with colic. The significant renal and hepatic dysfunctions in nonsurviving horses with colic appeared to be consistent with disseminated intravascular coagulation (DIC) and a grave prognosis.

Prevalence of acute kidney injury in a population of hospitalized horses

BACKGROUND

Hospital-acquired acute kidney injury (AKI) in humans and dogs increases morbidity and nonsurvival. Azotemia at presentation has been associated with a poor outcome in horses; however, prevalence and consequences of hospital-acquired AKI are unreported.

HYPOTHESIS/OBJECTIVES

To evaluate the prevalence of AKI in hospitalized horses, risk factors associated with AKI, and the effect of AKI on short-term survival. We hypothesized that the prevalence of AKI in horses is similar to that reported in other domestic mammalian species and would be associated with nonsurvival.

ANIMALS

Adult horses hospitalized for >2 days from which a minimum of 2 measurements of serum creatinine concentration were available.

METHODS

Retrospective cohort study. Clinical records were reviewed and horses grouped according to their baseline serum creatinine concentration and change in serum creatinine concentration from baseline. The associations between signalment, diagnosis, and treatment variables, and the presence of azotemia or AKI were assessed using multinomial logistic regression. The relationship between these conditions and survival to discharge was evaluated.

RESULTS

Three hundred twenty-five horses were included; 4.3% (14/325) had azotemia at baseline and 14.8% (48/325) developed AKI. There were no significant associations between investigated risk factors and development of AKI. The presence of azotemia and AKI did not significantly affect survival to discharge (P = .08 and .81, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

The prevalence of AKI in this population of hospitalized horses is similar to that reported in dogs and humans; however, in this study population, there was less impact on morbidity and short-term survival.

Cortisol and adrenocorticotropic hormone concentrations in horses with systemic inflammatory response syndrome

BACKGROUND

Plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations increase with illness-associated stress. Dynamics of plasma ACTH and serum cortisol concentrations in adult horses with systemic illness are undocumented.

HYPOTHESIS/OBJECTIVE

To determine whether ACTH and cortisol concentrations and the ACTH/cortisol ratio vary with survival, the presence of systemic inflammatory response syndrome (SIRS), or ischemic gastrointestinal lesions at admission, or throughout hospitalization.

ANIMALS

One hundred fifty-one adult horses.

METHODS

Prospective study measuring serum cortisol and plasma ACTH at admission and on days 2, 4, and 6 of hospitalization. Horses were grouped by outcome (survival, SIRS status, number of SIRS criteria [SIRS score], SIRS severity group, and the presence of an ischemic lesion). Differences between groups and over time for ACTH, cortisol, and ACTH/cortisol ratio were investigated with a mixed effect model. Receiving operator characteristic curves and odds ratios were calculated for survival and ischemia.

RESULTS

In all groups, ACTH, cortisol, and ACTH/cortisol ratio significantly decreased over time (P < .0001). ACTH, cortisol, and ACTH/cortisol ratio were higher at admission in nonsurvivors, and ACTH and cortisol were higher in horses with ischemic lesions (P < .01). Horses with ACTH above reference interval at admission were 6.10 (2.73-13.68 [95% confidence interval]) times less likely to survive (P < .0001). No significant difference in ACTH, cortisol, and ACTH/cortisol ratio between horses with different SIRS status, scores, or groups were detected, although nonsurvivors had a higher SIRS score (P < .0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Pituitary and adrenal responses are altered in nonsurviving horses and those with an ischemic gastrointestinal lesion.

A Comparative Review of Equine SIRS, Sepsis, and Neutrophils

The most recent definition of sepsis in human medicine can be summarized as organ dysfunction caused by a dysregulated host response to infection. In equine medicine, although no consensus definition is available, sepsis is commonly described as a dysregulated host systemic inflammatory response to infection. Defense against host infection is the primary role of innate immune cells known as neutrophils. Neutrophils also contribute to host injury during sepsis, making them important potential targets for sepsis prevention, diagnosis, and treatment. This review will present both historical and updated perspectives on the systemic inflammatory response (SIRS) and sepsis; it will also discuss the impact of sepsis on neutrophils, and the impact of neutrophils during sepsis. Future identification of clinically relevant sepsis diagnosis and therapy depends on a more thorough understanding of disease pathogenesis across species. To gain this understanding, there is a critical need for research that utilizes a clearly defined, and consistently applied, classification system for patients diagnosed with, and at risk of developing, sepsis.

Clinical Trials in Veterinary Medicine: A New Era Brings New Challenges

Randomized clinical trials (RCTs) are among the most rigorous ways to determine the causal relationship between an intervention and important clinical outcome. Their use in veterinary medicine has become increasingly common, and as is often the case, with progress comes new challenges. Randomized clinical trials yield important answers, but results from these studies can be unhelpful or even misleading unless the study design and reporting are carried out with care. Herein, we offer some perspective on several emerging challenges associated with RCTs, including use of composite endpoints, the reporting of different forms of risk, analysis in the presence of missing data, and issues of reporting and safety assessment. These topics are explored in the context of previously reported veterinary internal medicine studies as well as through illustrative examples with hypothetical data sets. Moreover, many insights germane to RCTs in veterinary internal medicine can be drawn from the wealth of experience with RCTs in the human medical field. A better understanding of the issues presented here can help improve the design, interpretation, and reporting of veterinary RCTs.