Equine neonatal sepsis

Case report: Fatal neonatal sepsis associated with Escherichia fergusonii infection in a common bottlenose dolphin (Tursiops truncatus)

A 25-day-old male common bottlenose dolphin (Tursiops truncatus) died suddenly while swimming at a dolphinarium. The gross examination revealed ulceration on the dorsal and pectoral fins and rostrum. Severe congestion, hemorrhage, and edema were observed in the gastrointestinal tract, liver, mesenteric lymph nodes, lungs, and kidneys. Fibrinosuppurative arthritis of the atlantooccipital joint and extension of fibrin into the spinal canal caused compression of the spinal cord. Histopathological examination revealed tracheitis, fibrinosuppurative bronchopneumonia and enteritis. In the central nervous system, meningeal vessel congestion in the brain, and intraparenchymal hemorrhages with neurodegeneration were observed in the spinal cord. Based on the histopathological findings, representative samples, including lung, liver, mesenteric lymph node, blood obtained from the jugular vein, and fluid sample of the ascites, were inoculated on tryptic soy agar and blood agar for routine bacterial isolation. Each isolated bacterial colony was streaked aseptically onto tryptic soy agar and blood agar for pure culture. After then, polymerase chain reaction (PCR) was performed for further identification of pathogenic microorganisms. PCR identified Escherichia fergusonii, Shewanella haliotis, Enterococcus faecalis, and Staphylococcus schleiferi. E. fergusonii was considered the primary etiologic agent in this case since it was the only species identified in all representative samples. The cause of death in this animal was E. fergusonii sepsis. To the best of our knowledge, this is the first case of neonatal sepsis associated with E. fergusonii infection in a dolphin, and suggests E. fergusonii as an opportunistic pathogen associated with sepsis in dolphins.

Red blood cell distribution width to platelet ratio in neonatal foals with sepsis

BACKGROUND

Rapid and accurate markers to aid diagnosis of sepsis are needed in neonatal foals. The CBC variable red blood cell distribution width (RDW) to platelet ratio (RPR) is associated with inflammatory response and linked to poor outcomes of sepsis in human patients.

HYPOTHESIS

Explore the correlation of RPR with sepsis in neonatal foals and evaluate RPR predictive and prognostic value.

ANIMALS

Three hundred seventeen hospitalized neonatal foals ≤7 days of age that had a CBC and physical exam performed at admission between 2012 and 2021.

METHODS

Retrospective case-control study. Clinical records were used to calculate sepsis scores and define groups. Red blood cell distribution width to platelet ratio was calculated and compared between groups (septic vs nonseptic) based on Kruskal-Wallis and Wilcoxon signed-rank tests. A multivariate logistic regression model to predict sepsis was created. The cutoff for RPR was obtained based on the maximal Youden Index. The Kaplan-Meier method and the log-rank test were used to estimate survival curves and compare survival rates based on RPR.

RESULTS

Red blood cell distribution width to platelet ratio was significantly higher in septic foals (Median = 0.099, confidence interval [CI] [0.093; 0.108]) than in sick nonseptic (0.085, CI [0.083; 0.089]) and healthy foals (0.081, CI [0.077; 0.086]; P < .0001). Red blood cell distribution width to platelet ratio was able to predict sepsis with high accuracy (AUC = 82.1%). The optimal RPR cutoff for sepsis was 0.09.

CONCLUSIONS AND CLINICAL IMPORTANCE

Red blood cell distribution width to platelet ratio calculation is practical, inexpensive, and based on CBC-derived data. Calculation of RPR along with CBC can aid in the diagnosis of sepsis and estimation of outcome.

Plasma UCHL-1 as a Biomarker of Brain Injury in Hospitalized Foals With Neonatal Encephalopathy

A plasma biomarker such as ubiquitin carboxyl-terminal hydrolase L1 (UCHL-1) to distinguish neonatal encephalopathy (NE) from other disorders and provide prognostic information would be useful for equine practitioners. In this prospective study, plasma UCHL-1 was measured in 331 hospitalized foals ≤4 days of age. Clinical diagnoses of neonatal encephalopathy only (NE group, n = 77), sepsis only (Sepsis group, n = 34), concurrent sepsis and NE (NE+Sepsis group, n = 85), or neither sepsis nor NE (Other group, n = 101) were made by the attending veterinarian. Plasma UCHL-1 concentrations were measured by ELISA. Differences between clinical diagnoses groups were evaluated and receiver operator curve (ROC) analysis was performed to assess diagnostic and prognostic performance. Median admission UCHL-1 concentration was significantly higher for NE (18.22 ng/mL; 7.93-37.43) and NE+Sepsis (17.42 ng/mL; 7.67-36.24) groups than Other foals (7.77 ng/mL; 3.92-22.76). Admission UCHL-1 was significantly higher in nonsurvivors (16.66 ng/mL; 6.89-34.84) than survivors (10.27 ng/mL; 5.82-29.94). Overall diagnostic performance of admission UCHL-1 concentration for NE diagnosis was determined (AUC 0.61; 95% confidence interval [CI] = 0.55-0.68); sensitivity and specificity for predicting NE were 73% and 49% respectively. Overall prognostic performance of time to lowest UCHL-1 concentration for predicting nonsurvival was determined (AUC 0.72; 95% CI = 0.65-0.79); sensitivity and specificity were 86% and 43% respectively. In this foal population, differences in plasma UCHL-1 concentrations were observed between foals with NE or NE with sepsis, and other diagnoses. The diagnostic and prognostic value of admission UCHL-1 concentration was limited.

Red cell distribution width values and red cell distribution width-to-platelet ratio in Thoroughbred foals in the first 24 hours of life

OBJECTIVES

To report red cell distribution width (RDW) values, to calculate RDW-to-platelet ratio (RPR), and to investigate a possible correlation of RDW and RPR index values in neonatal foals classified as healthy or at risk based on clinical information from a population of foals up to 24 hours of life.

DESIGN

Retrospective study conducted from records and CBCs of foals born between June and November from 2018 to 2020 foaling seasons.

SETTING

Breeding farm.

ANIMALS

Three hundred and nine neonatal full-term Thoroughbred foals.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Foals were evaluated by a veterinarian within 15 minutes after birth, and a blood sample was collected within 24 hours of life. Based on clinical information, 88 of 309 foals (28.4%) were considered at risk of perinatal disease, and 201 were healthy. Mean gestational age for the foals was 346.3 ± 9.7 days. RDW values did not differ between groups. Gestational length demonstrated to have a negative correlation with RDW (r = -0.156, P = 0.005) and mean corpuscular volume (r = -0.135, P = 0.01), indicating a link of these variables to foal maturity. RPR index was higher for at-risk (0.073 ± 0.018) than for healthy foals (0.068 ± 0.014, P = 0.01).

CONCLUSION

RPR might be a promising early indicator of disease for the field triage of neonatal foals.

The fecal bacterial microbiota of healthy and sick newborn foals

BACKGROUND

The fecal bacterial microbiota of normal foals and foals with enterocolitis has been characterized using next-generation sequencing technology; however, there are no reports investigating the gut microbiota in foals hospitalized for other perinatal diseases.

OBJECTIVE

To describe and compare the fecal bacterial microbiota in healthy and sick foals using next-generation sequencing techniques.

ANIMALS

Hospitalized (17) and healthy foals (21).

METHODS

Case-control study. Fecal samples were collected from healthy and sick foals on admission. Sick foals were further divided into sick nonseptic (SNS, n = 9) and septic (n = 8) foals. After extraction of DNA, the V4 region of the 16 S rRNA gene was amplified using a PCR assay, and the final product was sequenced with an Illumina MiSeq.

RESULTS

Diversity was significantly lower in healthy than sick foals (P < .05). The bacterial membership (Jaccard index) and structure (Yue & Clayton index) of the fecal microbiota of healthy, septic, and SNS foals were similar (AMOVA, P > .05). Bacterial membership (AMOVA, P = .06) and structure (AMOVA, P = .33) were not different between healthy and sick foals. Enterobacteriaceae, Enterococcus, and Streptococcus were among the 5 more abundant taxa identified in both groups.

CONCLUSION AND CLINICAL IMPORTANCE

Higher fecal microbiota diversity in sick than healthy foals might suggest a high exposure to environmental microorganisms or an unstable colonic microbiota. The presence of microorganisms causing bacteremia in foals in a high relative abundance in the feces of foals suggests the intestine might play an essential role in the causation of bacteremia in foals.

Serum amyloid A as a marker to detect sepsis and predict outcome in hospitalized neonatal foals

BACKGROUND

Serum amyloid A (SAA) has been reported to hold promise as diagnostic and prognostic marker in foals. This has not been investigated thoroughly.

OBJECTIVES

Evaluate admission SAA concentrations as predictor of sepsis and outcome.

ANIMALS

Five hundred and ninety hospitalized foals <14 days old.

METHODS

Retrospective multicenter study. Foals were scored with sepsis and survival scores, grouped according to health category (septic, sick but nonseptic, uncertain sepsis status) and outcome; septic foals were further categorized according to severity (normal sepsis, severe sepsis, and septic shock). SAA was compared between groups using Mann-Whitney test and Kruskal-Wallis test. Receiver operating characteristic curves identified optimal SAA cut off values for detecting sepsis and predicting outcome.

RESULTS

Admission SAA concentrations differed significantly between sick nonseptic foals (312.1 ± 685.4 mg/L) and septic foals (1079.7 ± 1254.5 mg/L) and increased with increasing sepsis score. SAA did not differ between sepsis severity groups. The optimal cut off for sepsis detection was 1050 mg/L (sensitivity 30.2%, specificity 90.7%). Admission SAA concentrations were lower in surviving (435.0 ± 723.6 mg/L) compared to nonsurviving foals (1062.7 ± 1440.1 mg/L) and decreased with increasing survival score. The optimal cut off for nonsurvival prediction was 1250 mg/L (sensitivity 22.1%, specificity 90.8%).

CONCLUSIONS AND CLINICAL IMPORTANCE

SAA concentration was higher in septic foals and nonsurviving foals. Even though optimal cut offs for SAA to detect sepsis and predict outcome had low sensitivity, they had good specificity. SAA can therefore be used as a marker to rule out sepsis and nonsurvival.

Clinical parameters of hypervirulent Klebsiella pneumoniae disease and ivermectin treatment in New Zealand sea lion (Phocarctos hookeri) pups

Hypervirulent Klebsiella pneumoniae infection causes significant mortality of endangered New Zealand sea lion pups at Enderby Island, Auckland Islands. Gross necropsy and histopathology findings are well reported, but little is known about the clinical course of disease in affected pups. To determine factors feasible as clinical screening tools for hypervirulent K. pneumoniae in live pups, 150 pups over two field seasons (2016–18) were recruited shortly after birth for a prospective cohort study. A randomised controlled clinical treatment trial with the anthelmintic ivermectin was conducted concurrently and risk factor data and biological samples were collected approximately fortnightly. Treatment with ivermectin has been demonstrated to reduce the risk of hypervirulent K. pneumoniae mortality in pups, so effects on clinical parameters between the treated and control cohorts were also investigated. A broader sample of pups were monitored for clinical signs to investigate the course of disease in affected pups. Clinical signs, haematology and oral and rectal swabs to detect gastrointestinal carriage of hypervirulent K. pneumoniae were not useful for detection of disease prior to death. Of those pups that died due to hypervirulent K. pneumoniae, only 26.1% (18/69) had any clinical signs prior, likely a reflection of the peracute course of disease. On comparison of haematological parameters between ivermectin-treated and control pups, significantly lower total plasma protein and higher eosinophil counts were seen in control versus treated pups, however standard length as a surrogate for age was a more important influence on parameters overall than ivermectin treatment. This study also highlighted a cohort of pups with severe clinical signs suggestive of hypervirulent K. pneumoniae infection were lost to follow up at the end of the monitored season, which could be contributing to cryptic juvenile mortality.

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

Uveitis is a sight-threatening eye disease in equids known worldwide that leads to considerable pain and suffering. By far the most common type of uveitis in Germany and neighboring countries is classical equine recurrent uveitis (ERU), which is caused by chronic intraocular leptospiral infection and is the main cause of infectious uveitis in horses. Other infectious causes are extremely rare and are usually clinically distinguishable from ERU. ERU can be treated very effectively by vitreous cavity lavage (vitrectomy). For proper indications of this demanding surgery, it is necessary to differentiate ERU from other types of uveitis in which vitrectomy is not helpful. This can be conducted on the basis of anamnesis in combination with ophthalmologic findings and by aqueous humor examination. During vitrectomy, vitreous material is obtained. These vitreous samples have historically been used for numerous etiologic studies. In this way, a chronic intraocular leptospiral infection has been shown to be the cause of typical ERU and, among other findings, ERU has also been recognized as a biofilm infection, providing new insights into the pathogenesis of ERU and explaining some thus far unexplainable phenomena of ERU. ERU may not only have transmissible aspects to some types of uveitis in humans but may also serve as a model for a spontaneously occurring biofilm infection. Vitreous material obtained during therapeutically indicated vitrectomy can be used for further studies on in vivo biofilm formation, biofilm composition and possible therapeutic approaches.

Peripheral blood markers of sepsis in foals born from mares with experimentally induced ascending placentitis

BACKGROUND

Neonatal sepsis is a leading cause of neonatal death during the first-week postfoaling. Despite recent advancements in the diagnosis and treatment of sepsis in the newborn foal, the non-specific clinical signs and subtle nature of this disease may result in delayed diagnosis until severe progression of the disease; thus, early detection of sepsis remains critical for a favourable outcome. This study aimed to identify early blood markers as predictive of sepsis on foals.

METHODS

Thirty-five foals were allocated into three groups: healthy control foals (n=7) and foals born from mares with placentitis: septic foals (n=9) and non-septic foals (n=19). Blood samples were obtained immediately after foaling and at 12, 24 and 48 hours. All samples were assessed for glucose, lactate, triglycerides, total cholesterol, urea, creatinine, total solids, fibrinogen, gamma-glutamyl transferase (GGT), serum amyloid A (SAA) and alpha-fetoprotein (AFP) concentrations.

RESULTS

At foaling, glucose and GGT concentrations were lower in septic foals (P<0.001). Of interest, SAA, AFP, creatinine and total cholesterol were higher in septic foals at parturition (P<0.05). At 12 hours, lactate, triglycerides and total cholesterol concentrations were higher in septic foals. When evaluated at 24 and 48 hours, higher concentrations of SAA and AFP were found in placentitis foals than in the control group.

CONCLUSIONS

Total cholesterol and lactate appear to be suitable markers for sepsis during the first 24 hours postpartum. Septic foals displayed altered energy metabolisms as determined by increased triglycerides and cholesterol concentrations, hypoglycaemia at birth and reduced activity of the GGT and increased lactate and urea concentrations. Sepsis was associated with high concentrations of SAA and AFP.

Serum cortisol and thyroid hormone concentrations and survival in foals born from mares with experimentally induced ascending placentitis

Background

There are few publications on occurrence of nonthyroidal illness syndrome in foals and on the prognostic value of cortisol and thyroid hormone (TH) concentrations in newborn foals.

Objectives

To determine serum cortisol and TH concentrations (total and free thyroxine: T₄ and _FT₄; total and free triiodothyronine: T₃ and _FT₃) in foals born from mares with placentitis, to determine their association with survival, and their use as prognostic markers.

Animals

A cohort of 29 newborn foals comprising 5 Control, 14 Low‐risk, and 10 Sick foals were evaluated over the first week of life.

Methods

In this prospective study foals born to mares with experimentally‐induced placentitis were assigned to Low‐risk or Sick groups while foals born to control mares were classified as Control based on clinical findings. Foals were also classified as Term (n = 13), Dysmature (n = 7), or Premature (n = 9), and survival rate was recorded. Serum cortisol and TH hormone concentrations were measured at 0, 12, 24, 48, and 168 hours of life.

Results

Sick non‐surviving foals had lower (P < .05) T₃ : cortisol ratio at 12 (3.68 ± 1.06 versus 18.58 ± 2.78), 24 (5.47 ± 2.34 versus 23.40 ± 3.82), and 48 (10.47 ± 6.29 versus 26.6 ± 2.90) hours of life when compared to Sick surviving foals and lower (P < .05) T₄ : cortisol ratio at 12 (75.12 ± 21.71 versus 414.47 ± 58.47) and 24 hours (127.83 ± 55.21 versus 430.87 ± 80.31) after birth than Sick surviving foals.

Conclusion and Clinical Importance

Placental infections can impair fetal thyroid function. Low T₃ : cortisol and T₄ : cortisol ratios seem to be good prognostic markers in newborn foals.

Short-term outcome and risk factors for post-operative complications following umbilical resection in 82 foals (2004-2016)

BACKGROUND

Umbilical remnant infection and patent urachus are an important cause of morbidity for the equine neonate. Left untreated, fatal complications can develop. Identifying risk factors for post-operative complications after surgery are important for estimating prognosis.

OBJECTIVES

To identify risk factors associated with post-operative complications in foals undergoing umbilical remnant resection due to patent and/or infected umbilical remnants.

STUDY DESIGN

Retrospective case series.

METHODS

Foals undergoing umbilical remnant resection due to patent urachus or infected remnants at the Marion duPont Scott Equine Medical Center from 2004 to 2016 were included in the study. Data were obtained from medical records and associations between outcomes and post-operative complications, and pre or intraoperative clinical variables were assessed using bivariable and multivariable analyses.

RESULTS

Eighty-two foals underwent umbilical remnant resection of which 73 (89.0%) survived to discharge. The urachus was the most commonly affected structure being patent and/or infected in 84.1% of cases. Concurrent diseases were present in 60.6% of foals prior to surgery, with diarrhoea and septic arthritis being most common. The presence of preoperative septic arthritis and/or physitis were significantly associated with nonsurvival (OR 33; 95% confidence interval 1.1-985.2; P = 0.04). Longer anaesthesia time (OR 1.4; 95% confidence interval 1.1-1.7; P = 0.02) and failure of passive transfer of immunoglobulins (OR 5.9; 95% confidence interval 1.2-29.04; P = 0.03) were associated with increased odds for post-operative complications.

MAIN LIMITATIONS

It is not known if medical treatment alone would have been successful in foals that did not receive preoperative medical treatment.

CONCLUSIONS

Overall survival is high after surgical excision of umbilical remnants. The presence of preoperative septic arthritis and/or physitis was associated with decreased survival and failure of passive transfer of immunoglobulins and longer anaesthesia times were associated with increased odds for post-operative complications.

Expression of von Willebrand factor, pulmonary intravascular macrophages, and Toll-like receptors in lungs of septic foals

Sepsis causes significant mortality in neonatal foals; however, there is little data describing the cellular and molecular pathways of lung inflammation in septic foals. This study was conducted to characterize lung inflammation in septic foals. Lung tissue sections from control (n = 6) and septic (n = 17) foals were compared using histology and immunohistology. Blinded pathologic scoring of hematoxylin and eosin stained samples revealed increased features of lung inflammation such as thickened alveolar septa and sequestered inflammatory cells in septic foals. Septic foal lungs showed increased expression of von Willebrand factor in blood vessels, demonstrating vascular inflammation. Use of MAC387 antibody to detect calprotectin as a reflection of mononuclear cell infiltration revealed a significant increase in their numbers in alveolar septa of lungs from septic foals compared to those from control foals. The mononuclear cells appeared to be mature macrophages and were located in the septal capillaries, suggesting they were pulmonary intravascular macrophages (PIMs). Finally, lungs from septic foals showed increased expression of Toll-like receptor 4 and 9 in mononuclear cells relative to the control. Taken together, this study is the first to show the expression of inflammatory molecules and an increase in PIMs in lungs from foals that died from sepsis.

Detection and DNA quantification of Enterococcus casseliflavus in a foal with septic meningitis

CASE DESCRIPTION A 3-month-old 180-kg (396-lb) Hanoverian colt was examined because of fever, lethargy, inappetence, drooping of the left ear, and stiff neck posture. Initial treatment included empirical antimicrobial treatment and NSAIDs. CLINICAL FINDINGS Initial findings were consistent with CNS anomalies. Endoscopy revealed hyperemia, ecchymosis, and some mucopurulent exudate in the right guttural pouch. Hematologic findings were consistent with neutrophilic inflammation. On the third day of hospitalization, severe neurologic signs were observed. Computed tomography of the skull revealed a comminuted fracture of the axial aspect of the right mandibular condyle. Examination of CSF revealed turbidity, xanthochromia, and intracellular and extracellular cocci, consistent with septic meningitis. After DNA extraction from blood and CSF, sequenced products from a PCR assay for the bacterial 16S rRNA gene were 99% identical to Enterococcus casseliflavus. Microbial culture of CSF and blood samples yielded bacteria with Enterococcus spp morphology; antimicrobials were selected on the basis of susceptibility testing that identified the isolate as vancomycin resistant. A quantitative PCR assay was used to estimate Enterococcus DNA concentrations in CSF and blood. TREATMENT AND OUTCOME Treatment for E casseliflavus meningitis, including trimethoprim-sulfadiazine and ampicillin sodium administration, resulted in resolution of clinical signs. Culture of CSF and blood samples after 12 days of the targeted treatment yielded no growth. CLINICAL RELEVANCE To the authors' knowledge, this was the first report of E casseliflavus meningitis in a horse. Treatment was successful; vancomycin-resistant enterococci can be a clinical problem and may potentially be zoonotic.

A review of equine sepsis

Sepsis is defined as an exaggerated, systemic inflammatory response to infection and is a common condition in horses. Systemic inflammatory response syndrome (SIRS) associated with bacterial infection is a hallmark of sepsis. Sepsis in neonatal foals is a common sequela of failure of passive transfer and, in addition to development of SIRS, may be characterised by bacteraemia, pneumonia, enterocolitis, omphalophlebitis, meningoencephalitis or arthritis. Sepsis in mature horses is most commonly observed secondary to gastrointestinal lesions that result in disrupted mucosa and bacterial translocation into circulation (endotoxaemia). Pleuropneumonia and metritis may also cause sepsis in mature horses. Diagnosis of sepsis is based on SIRS criteria as well as suspected or confirmed infection. Due to the relatively low sensitivity of microbial culture and the subjectivity of sepsis scoring, many sepsis biomarkers are being studied for their usefulness in diagnosis and prognostication of sepsis in horses. Treatment of sepsis requires an intensive care approach that includes antimicrobial drug administration, fluid resuscitation and pressure support, and treatment for inflammation, endotoxaemia and coagulopathy. Early recognition of sepsis and prompt antimicrobial drug treatment are critical for a successful outcome. Multiple organ dysfunction syndrome may occur in severe cases of sepsis, with common manifestations including laminitis and coagulopathies. Although prognosis for septic mature horses depends highly on the primary disease process, the overall survival rate in septic neonatal foals ranges from 26 to 86%, with most studies indicating a survival rate of 45-60%.

Antimicrobial use in critically ill horses

OBJECTIVE

To discuss controversies surrounding antimicrobial use in critically ill horses.

DATA SOURCES

PubMed searches from 1970-present for terms including, but not limited to: "horse," "foal," "antimicrobial," "prophylaxis," "infection," "surgery," "sepsis," and "antimicrobial resistance."

HUMAN DATA SYNTHESIS

Increasing bacterial antimicrobial resistance has changed first-line antimicrobial choices and prompted shortening of the duration of prophylactic and therapeutic treatment. The need to decrease bacterial resistance development to critically important antimicrobials has been highlighted.

VETERINARY DATA SYNTHESIS

Veterinary medicine has followed a similar trend but often without a high-level evidence. Common dilemmas include diseases in which the theoretically most effective drug is a reserved antimicrobial, the inability to differentiate infectious from noninfectious disease, the duration and necessity of prophylactic antimicrobials and use of antimicrobials in primary gastrointestinal disease. These problems are illustrated using examples of purulent infections, neonatal sepsis, colic surgery, and treatment of colitis. Although enrofloxacin, cephalosporins, and doxycycline, in contrast to gentamicin, reach therapeutic concentrations within the lungs of healthy horses, the first two should not be used as first line treatment due to their reserved status. Due to the high risk of bacterial sepsis, antimicrobial treatment remains indispensable in compromised neonatal foals but shortening the length of antimicrobial treatment might be prudent. One prospective randomized study demonstrated no difference between 3 and 5 days of perioperative antimicrobial treatment in colic surgery but shorter durations were not evaluated. High-level evidence to recommend antimicrobial treatment of adult horses with undifferentiated diarrhea does not exist.

CONCLUSIONS

Few evidence-based recommendations can be made. Commonly used antimicrobial combinations remain the mainstay for treating purulent infections. Antimicrobial treatment for compromised foals should not extend beyond recovery. Continuation of prophylactic antimicrobials >3 days is likely unnecessary after colic surgery; shorter durations might be equally effective. Antimicrobial prophylaxis in adult horses with diarrhea is unlikely to be beneficial.

Development of a likelihood of survival scoring system for hospitalized equine neonates using generalized boosted regression modeling

BACKGROUND

Medical management of critically ill equine neonates (foals) can be expensive and labor intensive. Predicting the odds of foal survival using clinical information could facilitate the decision-making process for owners and clinicians. Numerous prognostic indicators and mathematical models to predict outcome in foals have been published; however, a validated scoring method to predict survival in sick foals has not been reported. The goal of this study was to develop and validate a scoring system that can be used by clinicians to predict likelihood of survival of equine neonates based on clinical data obtained on admission.

METHODS AND RESULTS

Data from 339 hospitalized foals of less than four days of age admitted to three equine hospitals were included to develop the model. Thirty seven variables including historical information, physical examination and laboratory findings were analyzed by generalized boosted regression modeling (GBM) to determine which ones would be included in the survival score. Of these, six variables were retained in the final model. The weight for each variable was calculated using a generalized linear model and the probability of survival for each total score was determined. The highest (7) and the lowest (0) scores represented 97% and 3% probability of survival, respectively. Accuracy of this survival score was validated in a prospective study on data from 283 hospitalized foals from the same three hospitals. Sensitivity, specificity, positive and negative predictive values for the survival score in the prospective population were 96%, 71%, 91%, and 85%, respectively.

CONCLUSIONS

The survival score developed in our study was validated in a large number of foals with a wide range of diseases and can be easily implemented using data available in most equine hospitals. GBM was a useful tool to develop the survival score. Further evaluations of this scoring system in field conditions are needed.

Pattern recognition receptors in equine endotoxaemia and sepsis

Pattern recognition receptors (PRRs) on host cells detect pathogens to activate innate immunity which, in turn, initiates inflammatory and adaptive immune responses. Successful activation of PRRs is, therefore, critical to controlling infections and driving pathogen‐specific adaptive immunity, but overactivity of PRRs causes systemic inflammation, which is detrimental to the host. Here we review the PRR literature as it relates to horses and speculate on the role PRRs may play in sepsis and endotoxaemia.

Retrospective Study of Necropsy-Associated Coagulase-Positive Staphylococci in Horses

Coagulase-positive staphylococci (CoPS) are potential causative agents of equine infections, but they are rarely responsible for the death of the animal. In the current study, staphylococci implicated in the death or euthanasia of horses were retrospectively studied in 3,457 necropsies performed over a decade (1995-2006). Morbidity associated with CoPS was 1.7%, representing 60 isolates of CoPS, which were identified as Staphylococcus aureus (59) and Staphylococcus pseudintermedius (1). Coagulase-positive staphylococci (alone or in association with another bacterial species) were associated with the death or euthanasia of 90% of the cases (54/60). Proportions of antibiotic resistance to penicillin G and tetracycline reached 62.7% and 23.7%, respectively. Virulence genes were detected in 91.7% of the strains, with a majority of seh or sei enterotoxin genes. Finally, 3 methicillin-resistant Staphylococcus aureus (MRSA) isolates belonging to the t064 spa-type were identified. One strain was isolated in 2003 and might thus be one of the first cases of equine MRSA in France.

Use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity

OBJECTIVE-To assess the use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity (FTPI). DESIGN-Cohort study. ANIMALS-232 Thoroughbred foals and 191 Thoroughbred mares (41 mares gave birth to 1 foal on 2 occasions). PROCEDURES-Postpartum, presuckle colostrum samples were collected from mares; samples with a colostral refractive index (cRI) > or = 23% were frozen (-20 degrees C [-4 degrees F]) and stored for > or = 7 days but < 2 years. Foals of dams that produced colostrum with a cRI value < 20% were treated with > or = 300 mL of stored colostrum that was thawed and administered via nasogastric tube on 1 to 4 occasions within 6 hours after parturition. Serum samples were obtained from colostrum-treated and nontreated foals 24 hours after treatment or suckling, respectively, for determination of serum IgG (sIgG) concentration. RESULTS-8 foals and their respective dams were excluded from the analyses. For the remaining 30 treated and 194 nontreated foals, mean +/- SD sIgG concentration was 1,597 +/- 574 mg/dL. Thirteen (5.8%) foals had sIgG concentrations < 800 mg/dL, of which 1 (0.4%) had an sIgG concentration < 400 mg/dL. Nine of these foals had suckled mares producing colostrum with a cRI value > or = 20%, and 2 foals had been treated with stored colostrum. CONCLUSIONS AND CLINICAL RELEVANCE-Treatment with stored colostrum appeared to be effective for prevention of FTPI in at-risk foals. However, foals were still at risk for FTPI despite suckling of or treatment with colostrum with adequate cRI values.