An updated description of bacterial pneumonia in adult horses and factors associated with death

BACKGROUND

Available descriptive studies on equine pneumonia are outdated or focus on specific horse or bacterial populations.

OBJECTIVES

To describe the clinical presentation and bacterial isolates of adult horses with bacterial pneumonia and identify factors associated with death.

ANIMALS

One hundred sixteen horses >2 years old with bacterial pneumonia.

METHODS

Retrospective case series. Data regarding history, physical examination, clinicopathologic features, treatment, bacterial culture and sensitivity, and outcome were collected and analyzed retrospectively.

RESULTS

Historical risk factors were present for 60% of cases, whereas abnormal vital signs on intake were present for <50%. Most horses (58%) underwent at least 1 change of antimicrobial treatment, and 67% received the highest-priority critically important antimicrobials. Streptococcus zooepidemicus was the most isolated bacteria (44%), followed by Escherichia coli (19%), Klebsiella spp. (18%), other Streptococcus species (17%), and Bacillus spp. (13%). Fusobacterium spp. were the most common anaerobic isolates (11%). Antimicrobial susceptibility varied widely. Survival to discharge was 73%. Heart rate at presentation (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.008-1.17, P = .03) and higher creatinine (OR 14.1, 95% CI 1.56-127.6, P = .02) increased the risk of death. Higher lymphocyte count (OR 0.27, 95% CI 0.08-0.94, P = .04) reduced risk.

CONCLUSIONS AND CLINICAL IMPORTANCE

Contrasting older literature, Fusobacterium spp. were the most common anaerobes. Streptococcus zooepidemicus remained the most common isolate and was predictably susceptible to penicillin. Antimicrobial susceptibility was otherwise variable and broad applicability is limited as this was a single-center study. Increased risk of death associated with tachycardia and abnormally high serum creatinine concentration is consistent with previous studies.

ECEIM consensus statement on equine kidney disease

The aim of this consensus statement is to summarize and appraise scientific evidence and combine this with the clinical experience of a panel of experts to optimize recommendations on how to recognize and manage kidney disease in horses.

Pharmacokinetics of amikacin after intravenous, intra-articular, and combined intravenous and intra-articular administration in healthy neonatal foals

BACKGROUND

Pharmacokinetics of amikacin administered IV to neonatal foals are described, but little data are available regarding the plasma concentrations contributed by concurrent intra-articular (IA) administration.

HYPOTHESIS/OBJECTIVES

Compare the pharmacokinetics of amikacin when the total dose is administered IV compared to being divided between IV and IA routes of administration in neonatal foals and predict the plasma concentrations from various combined IV and IA dosing regimens.

ANIMALS

Eight healthy neonatal foals.

METHODS

Foals received 3 amikacin treatment protocols: (1) IV-only (25 mg/kg q24h IV), (2) concurrent IV and IA (16.7 mg/kg q24h IV and 8.3 mg/kg q24h into 1 tarsocrural joint), and (3) IA-only (8.3 mg/kg q24h into 1 tarsocrural joint). Protocols were administered for 3 days beginning at 7, 14, and 21 days of age. Plasma concentrations ≥53 μg/mL at 30 minutes were considered therapeutic for isolates with intermediate susceptibility.

RESULTS

Foal age was a significant variable. The IV-only protocol met or exceeded the 30-minute plasma concentrations considered therapeutic (mean μg/mL [95% confidence interval, CI]) in 7- to 9-day-old (54.0 [52.2-56.9]), 14- to 16-day-old (58.1 [55.2-61.0]), and 21- to 23-day-old (66.6 [63.7-69.6]) foals. Concurrent IV and IA protocol did not reach the 30-minute concentration considered therapeutic in 7- to 9-day-old foals (46.5 [43.6-49.4]) but did in 14- to 16-day-old (62.9 [60.0-65.8]) and 21-to 23-day-old (62.6 [59.7-65.6]) foals.

CONCLUSIONS AND CLINICAL IMPORTANCE

Concurrent IV and IA administration of amikacin produces 30-minute plasma concentrations considered therapeutic in foals 14 to 23 days old, but concentrations observed in younger foals might be below those considered therapeutic for isolates with intermediate susceptibility to amikacin.

Association of the neutrophil-lymphocyte ratio with outcome in sick hospitalized neonatal foals

BACKGROUND

The neutrophil-lymphocyte ratio (NLR) in human medicine is an objective biomarker that reflects prognosis. The NLR as an independent biomarker to help predict nonsurvival in hospitalized neonatal foals has not been thoroughly interrogated.

OBJECTIVES/HYPOTHESIS

Retrospectively evaluate if the NLR at admission is associated with nonsurvival in sick hospitalized foals <4 days old. We hypothesized that a lower NLR will be associated with nonsurvival.

ANIMALS

One thousand one hundred ninety-six client-owned foals <4 days old of any breed and sex: 993 hospitalized foals and 203 healthy foals.

METHODS

Retrospective multicenter study. Medical records of foals presenting to 3 equine referral hospitals were reviewed. Foals were included if they had complete CBCs, sepsis scores, and outcome data. The NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. Data were analyzed by nonparametric methods and univariate analysis.

RESULTS

Of the 993 sick hospitalized foals, 686 were sick nonseptic and 307 were septic. The median NLR was lower in sick hospitalized foals (median [95% confidence interval], 3.55 [0.5-13.9]) compared with healthy foals (6.61 [3.06-18.1]). Septic foals had the lowest NLR (2.00 [0.20-9.71]). The NLR was lower in nonsurviving (1.97 [1.67-2.45]) compared with surviving foals (4.10 [3.76-4.33]). Nonsurviving septic foals had the lowest NLR (1.47 [1.70-3.01]). Foals with a NLR of <3.06 or <1.6 at admission had odds ratio of 3.21 (2.24-4.29) and 4.03 (2.86-5.67) for nonsurvival, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

A NLR < 3.06 at admission in sick hospitalized foals is readily available and clinically useful variable to provide prognostic information.

Neonates and Periparturient Mares: Tips and Tricks for Diagnosis and Management

Colic is a common presenting complaint in foals. Unfortunately, evaluation of foals with colic can be difficult due to the common clinical presentation of acute abdominal pain attributable to a wide variety of disorders and a broad range of etiologies. Similar to foals, colic is one of the most common diseases of pregnant and periparturient mares. Several conditions are unique or occur more commonly in broodmares. This article reviews the most commonly encountered types of colic events in neonatal foals and periparturient mares, how to correctly diagnose these conditions, as well as details concerning appropriate medical management and/or surgical intervention.

Changes in serum total protein and immunoglobulin G concentrations and Brix percentages in neonatal Arabian foals from birth up to 21 days of age

The aim of this study was to evaluate changes in the serum immunoglobulin G (IgG) and serum total protein (STP) concentrations and serum Brix percentages of neonatal Arabian foals during first 3 weeks of life. Blood samples were collected from 12 apparently healthy foals by jugular venipuncture at birth and at 12-hours, 24-hours, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15 and 21 days of age. Serum IgG and STP concentrations and Brix percentages were measured by the radial immunodiffusion assay, and digital STP and Brix refractometers, respectively. Based on the serum IgG concentrations measured at 24 h, two foals were diagnosed with failure of transfer of passive immunity (FTPI). While IgG concentrations were determined using the data of foals with adequate transfer of passive immunity, other calculations were made using the data of all foals. The mean IgG concentration of the foals increased from birth (<200 mg/dl) to 12 (2068.5 mg/dl) and 24 h (2184.7 mg/dl), and progressively decreased up to 21 days of age (1318.5 mg/dl). The serum IgG concentrations at 12 h were highly correlated with each of the IgG concentrations measured over the 21-day period. The serum IgG and STP concentrations and Brix percentages of the foals diagnosed with FTPI at 12 h did not reach the adequate strata over time. These results suggest that foals can be reliably tested for passive immunity status at 12 h after birth.

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.

Evaluation of refractometry methods for estimating passive immunity status in neonatal foals

The objective of this cross-sectional study was to determine the accuracy of the digital Brix and serum total protein (TP) refractometers for estimating different passive immunity status in neonatal foals. In total, 18- to 40-h old purebred Arabian foals (n = 185) were used. Serum TP concentrations, total solid percentages and IgG concentrations were measured with a digital serum TP refractometer, digital Brix refractometer and the gold standard radial immunodiffusion (RID) assay, respectively. Correlation coefficients were calculated between the refractometer and RID assay results. A receiver operating characteristic analysis was used to select the optimal cut-offs for both refractometers. Test performance and agreement were evaluated using diagnostic test characteristics at optimal thresholds and areas under the ROC curve, and by calculating Cohen's kappa coefficient. The sensitivity and specificity of the digital Brix refractometer at optimal cut-offs (≤7.8%, ≤7.9%, ≤8.2%, ≤8.3%, ≤9.0%) were 100 and 69.3%; 100% and 68.5%; 70.5% and 71.0%; 88.3% and 85.5%; 88.1% and 76% to estimate RID-IgG of <400 mg/dL, <800 mg/dL, <1500 mg/dL, <2500 mg/dL and < 3000 mg/dL, respectively. The sensitivity and specificity of the digital serum TP refractometer at optimal cut-off (≤4.6 g/dL, ≤4.6 g/dL, ≤4.8 g/dL, ≤5.0 g/dL, ≤5.4 g/dL) were 100 and 69.3%; 100% and 72.8%; 90% and 72.8%; 72.9% and 83.9%; 84.4% and 88% to estimate RID-IgG of <400 mg/dL, <800 mg/dL, <1500 mg/dL, <2500 mg/dL and < 3000 mg/dL, respectively. In conclusion, the refractometers showed a good potential as screening tools for the estimation of different IgG concentrations in neonatal foals.

Neurologic Disorders of the Foal

Neurologic disease of foals is a diagnostic and therapeutic challenge for veterinarians. Disease conditions such as neonatal encephalopathy are seen as well as developmental and congenital defects, bacterial infections, and trauma. Neonatal encephalopathy can be considered a "syndrome" with a variety of causes resulting in a similar clinical presentation. These causes can be categorized as maladaptation, hypoxic/ischemic encephalopathy, and metabolic abnormalities, all leading to signs of cerebral and brainstem disease. Spinal cord signs may occasionally be seen, but these signs are usually overshadowed by cerebral disease. Treatment in most cases involves supportive care and outcome is favorable in most cases.

Emergency Management of Equid Foals in the Field

Foal emergencies can be intimidating to manage in the field, yet many conditions will respond well to the supportive care possible on the farm. Triage of the foal targets focused supportive care to stabilize the foal before referral to a hospital or to facilitate the management in the field. There are many diagnostic and therapeutic options available in the field setting to support a successful outcome on the farm.

The effect of neonatal dysphagia on subsequent racing performance in Standardbred horses

BACKGROUND

Previously we described a clustering of dysphagic foal cases on a Pennsylvania (PA) Standardbred farm which was associated with exposure of pregnant mares to high concentrations of polycyclic aromatic hydrocarbons (PAHs) in the well water. The effect of dysphagia on future athleticism was uncertain.

OBJECTIVES

To determine if, as adults, dysphagic foals were less likely to race and if athleticism (age of first race, Speed Index and Earnings Per Start Index) differed from that of healthy foals that raced as adults.

STUDY DESIGN

Prospective cohort study.

METHODS

All foals born during the study period (2014-2017) on the affected PA or an unaffected New York (NY) farm with the same proprietor were eligible for inclusion in the study. Foals with dysphagia attributed to causes other than PAH environmental exposure were excluded. The proportion of foals from both farms that raced, their age of first race, Earnings Per Start Index and Speed Index were compared between the dysphagic and normal foals using Chi-Square and Wilcoxon Rank Sum Tests. Significance level was P < .05.

RESULTS

A total of 116 foals met the inclusion criteria. No significant difference was found in the percentages of foals that raced from each farm: On the PA farm, 54% of healthy and 72% of dysphagic foals raced; 70% of healthy NY farm foals raced. Median (interquartile range) age of first race, Earnings Per Start Index or Speed Index for dysphagic foals (2 years (2, 2); 57 (49, 60); 60 (45, 66) was not different from those of healthy foals from both farms (2 years (2, 3); 55 (39, 78)) or the PA farm (2 years (2, 2); 61(24, 73); 68 (57, 85)). All P > .05.

MAIN LIMITATIONS

Small sample size and unique type of dysphagia.

CONCLUSIONS

The athleticism of formerly dysphagic foals does not appear to be negatively impacted compared with normal foals as measured by age of first race, Earnings Per Start Index and Speed Index.

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.

Investigation of neonatal disorders in New World camelids and factors associated with death during and after hospitalization of affected crias

OBJECTIVE

To assess signalment, clinical findings, and treatments for New World camelids (NWCs) hospitalized for evaluation and treatment of neonatal disorders and investigate associations between these factors and death during and after hospitalization.

ANIMALS

267 NWCs ≤ 30 days of age.

PROCEDURES

Medical records of a veterinary teaching hospital were retrospectively reviewed to identify NWCs admitted for evaluation and treatment of neonatal disorders between 2000 and 2010. Signalment, physical examination data, diagnostic findings, treatments, and outcomes were recorded. Factors were examined for association with death during hospitalization and the overall hazard of death by use of multivariable logistic regression and Cox proportional hazards analysis, respectively.

RESULTS

The sample comprised alpacas (n = 255) and llamas (12). Median age at admission was 3 days, and median hospitalization time was 2 days; 208 of the 267 (77.9%) neonatal NWCs survived to hospital discharge. Factors associated with increased odds of death during hospitalization included prematurity or dysmaturity, hypothermia, sepsis, toxic changes in neutrophils, and undergoing surgery. The odds of death during hospitalization also increased as anion gap increased. After discharge, 151 of 176 (85.8%) animals had follow-up information available (median follow-up time, 2,932 days); 126 (83%) were alive and 25 (17%) had died. Prematurity or dysmaturity, congenital defects, sepsis, oxygen administration, and undergoing surgery as a neonate were associated with an increased hazard of death; the hazard of death also increased as serum chloride concentration at the time of hospitalization increased.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested the prognosis for survival during and after hospitalization is good for most NWCs hospitalized because of neonatal disorders.

Plasma disposition of ceftazidime in healthy neonatal foals following intravenous and intramuscular administration

Cephalosporin antimicrobials can be utilized for the treatment of sepsis in neonatal foals, particularly when an aminoglycoside is contraindicated. Some cephalosporins, however, are not utilized because of cost, sporadic availability, or uncertainty about efficacy. The plasma disposition of ceftazidime, a third-generation cephalosporin with a broad spectrum of activity against a wide variety of gram-negative bacteria and minimal renal side effects has not been reported in neonatal foals. In this study, the plasma disposition of single intravenous (IV) and intramuscular (IM) doses of ceftazidime in neonatal foals was determined. Six healthy one to two-day-old foals were given 25 mg/kg of ceftazidime by IV and IM routes in a cross-over design, with a 48-h washout period between doses. Non-compartmental analysis was used to estimate plasma pharmacokinetic parameters. Median t_1/2 was 2 h and median AUC_0-last was 364 µg h/ml for both IV and IM administration. Median C_max after IM administration was 101 µg/ml, with a median T_max of 0.7 h. Relative bioavailability of IM injection was 90%. There were no statistically significant differences between estimated IV and IM pharmacokinetic parameters. Plasma concentrations remained above the human CLSI susceptible breakpoint for Enterobacteriaceae for over 8 h following IV and IM administration.

Factors associated with survival and racing performance of 114 Thoroughbred foals with septic arthritis compared with maternal siblings (2009-2015)

BACKGROUND

There is little consensus on factors associated with survival in foals with septic arthritis and limited data on long-term racing performance of Thoroughbred foals treated for septic arthritis. A more thorough understanding of short- and long-term outcome is necessary to help inform owners, and subsequently guide treatment.

OBJECTIVES

To investigate factors associated with survival, and to analyse racing performance of foals with septic arthritis compared with their maternal siblings.

STUDY DESIGN

Retrospective cohort and a case-control study.

METHODS

Veterinary clinical records of Thoroughbred foals ≤180 days old that underwent arthroscopic, cannulae or through-and-through needle lavage for the treatment of septic arthritis between 2009 and 2015 were reviewed. Data included signalment, and clinicopathological information. The dam's foaling records were reviewed and the lifetime racing records were obtained for affected foals and two of their maternal siblings. Logistic regression analysis was used to determine factors associated with survival to discharge or racing. Comparisons between treated foals and their maternal siblings were made.

RESULTS

Ninety (78%) of 115 foals diagnosed with septic arthritis were discharged alive. Foals <26 days old at the time of admission were five times less likely (P = .003) and foals with concurrent multisystemic disease were six times less likely (P = .02) to be discharged alive. Sixty (67%) foals discharged alive started in ≥1 race, and there was no difference in the proportion of foals that started in a race or racing performance between foals treated for septic arthritis and their maternal siblings.

MAIN LIMITATIONS

Retrospective study design, limited number of foals with multiple joint involvement and failure to accurately record duration of clinical signs.

CONCLUSIONS

Foals treated for septic arthritis at the Scone Equine Hospital, New South Wales, Australia had a good prognosis for survival, and for this cohort, foals that survived to discharge had a similar ability to race as their maternal siblings.

Cumulative antibiogram and multidrug-resistant organisms in a regional equine referral hospital

Prudent use of antimicrobials is paramount to slow the development of resistance and for successful treatment. The use of cumulative antibiograms will allow evidence-based antimicrobial selection with consideration of local resistance patterns. We generated a "first-isolate-per-patient" cumulative antibiogram for a regional equine referral hospital. Bacterial organisms cultured from horses between 2011 and 2018, sample origin, antimicrobial susceptibilities, and multidrug-resistant (MDR) status were tabulated. Of 1,176 samples, 50% were culture positive. Overall, 93 of 374 (25%) were MDR. Of the MDR isolates, 11 (12%) were susceptible to high-importance antimicrobials only (as defined by the Australian Strategic and Technical Advisory Group on antimicrobial resistance). β-hemolytic streptococci were uniformly susceptible to penicillin (76 of 76); 17 of 20 (85%) non-β-hemolytic Streptococcus spp. were susceptible to penicillin. Despite veterinary-specific challenges in constructing an antibiogram, our study provides an exemplar of the clinical utility of regional-, farm-, or hospital-specific cumulative antibiograms for evidence-based empirical antimicrobial selection by veterinarians prior to susceptibility result availability.

Differences in isolation rate and antimicrobial susceptibility of bacteria isolated from foals with sepsis at admission and after ≥48 hours of hospitalization

Background

Antimicrobial treatment protocols for foals with sepsis that do not improve clinically often are adjusted based on bacteriological and antimicrobial susceptibility testing results from samples collected at hospital admission.

Objectives

To evaluate whether hospitalization for ≥48 hours affects bacteriological and antimicrobial susceptibility testing results.

Animals

Two‐hundred sixty‐seven foals <30 days of age admitted to a neonatal intensive care unit and diagnosed with sepsis.

Methods

Medical records were reviewed retrospectively to identify foals with sepsis and positive bacteriological cultures. Results from samples collected at hospital admission were compared to those collected ≥48 hours after admission. Logistic regression for clustered data and exact logistic regression were used for statistical analysis.

Results

Three‐hundred fifty‐three unique bacterial isolates were obtained from 231 foals at hospital admission and 92 unique bacterial isolates were obtained from 57 foals after ≥48 hours of hospitalization. Relative isolation frequency after ≥48 hours of hospitalization increased for Acinetobacter spp., 0.6% versus 3.3% (odds ratio [OR], 7.63; 95% confidence interval [CI], 1.28‐45.45); Enterococcus spp., 4.8% versus 19.6% (OR, 5.37; 95% CI, 2.64‐10.90); Klebsiella spp., 5.1% versus 10.9% (OR, 2.27; 95% CI, 1.05‐4.89); Pseudomonas spp., 3.0% versus 7.6% (OR, 3.49; 95% CI, 3.49‐240.50); and Serratia spp., 3.0% versus 5.4% (OR, 20.23; 95% CI, 2.20‐186.14). Bacteria isolated after ≥48 hours of hospitalization were less susceptible to all tested antimicrobial drugs, except for imipenem.

Conclusions and Clinical Importance

Decreased antimicrobial susceptibility of bacteria isolated after ≥48 hours of hospitalization provides a rationale for repeated bacteriological culture and susceptibility testing in hospitalized foals with sepsis.

Factors associated with long-term athletic outcome in Thoroughbred neonates admitted to an intensive care unit

BACKGROUND

Limited information exists on the long-term outcome of foals that survive following hospitalisation for disease as a neonate. Significant financial investment is required to raise foals to racing age, therefore improved understanding of factors that affect long-term outcome and future athletic performance is important.

OBJECTIVES

To analyse racing performance in Thoroughbred foals hospitalised as neonates, compared with their maternal siblings and to determine factors associated with failure to race and racing performance.

STUDY DESIGN

Retrospective cohort study.

METHODS

Medical records of Thoroughbred foals admitted to a neonatal intensive care unit between 1982 and 2008 were reviewed. Surviving foals of registered mares were included. Data including the foal's primary and concurrent diseases were extracted from the medical record. Racing records for foals and maternal siblings were evaluated. Multivariable logistic regression was used to identify disorders associated with failure to race and decreased racing performance.

RESULTS

Two-hundred and sixty-nine of 454 previously hospitalised foals (59%) raced. Sixty-eight percent (269/394) of registered foals raced, compared with 79% (697/880) of registered siblings. Foals with prematurity/dysmaturity (P = 0.002) and those with orthopaedic disease (P = 0.007) were significantly less likely to race than their siblings. Premature/dysmature foals also had significantly fewer starts and wins and lower earnings than siblings. Foals with orthopaedic disorders had a lower percentage of wins, relative to their siblings. There was no significant association between racing performance and other disease categories.

MAIN LIMITATIONS

Small sample size in some disease categories and retrospective nature of study.

CONCLUSIONS

Foals hospitalised due to prematurity/dysmaturity or orthopaedic disorders were less likely to race than their maternal siblings and those that did race had decreased performance.

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 findings and diagnostic test results for calves with septic arthritis: 64 cases (2009-2014)

OBJECTIVE To describe clinical findings and diagnostic test results and identify potential prognostic indicators for calves with septic arthritis. DESIGN Retrospective case series. ANIMALS 64 calves with septic arthritis. PROCEDURES The medical record database for a veterinary teaching hospital was searched to identify calves ≤ 6 months old that were treated for septic arthritis between 2009 and 2014. Data evaluated included signalment, history, physical examination and diagnostic test results, treatment, and outcome. Descriptive data were generated, and calves were assigned to 2 groups (neonatal [≤ 28 days old] or postneonatal [29 to 180 days old]) on the basis of age at hospital admission for comparison purposes. RESULTS 64 calves had 92 infected joints; 17 calves had polyarthritis. Carpal joints were most frequently affected followed by the stifle and tarsal joints. Forty-nine bacterial isolates were identified from synovial specimens for 38 calves, and the most commonly identified isolates were catalase-negative Streptococcus spp (n = 14) and Mycoplasma bovis (9). Calves in the neonatal group had a shorter interval between onset of clinical signs and hospitalization and were more likely to have an infected carpal joint than calves in the postneonatal group. Outcome was positive for 35 calves. Synovial fluid total nucleated cell count was positively associated with a positive outcome. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that empirical antimicrobial treatment for calves with septic arthritis should target gram-positive catalase-negative cocci and M bovis and that synovial fluid total nucleated cell count might be a useful prognostic indicator.

Initial antimicrobial treatment of foals with sepsis: Do our choices make a difference?

The study objectives were to provide cumulative antimicrobial susceptibility data at the patient level and to evaluate the effect of initial antimicrobial treatment on survival in foals with sepsis. Foals below 30days of age with a diagnosis of sepsis, confirmed by isolation of bacteria from normally sterile sites on the day of hospital admission, were included. Susceptibility testing was performed using the broth microdilution procedure. In total, 213 foals and 306 bacterial isolates were included. The likelihood of survival for foals from which all bacteria were susceptible to the initial antimicrobial treatment was 65.4% (n=106/162; 95% confidence interval (CI) 57.6% to 72.7%) versus 41.7% (n=10/24; 95% CI 22.1% to 63.4%) if one or more isolates were resistant (relative risk 1.57, 95% CI 0.96 to 3.06). Based on this study, amikacin combined with ampicillin remains an appropriate antimicrobial drug combination for initial treatment of foals with sepsis.

Surgical management and long-term outcome of umbilical infection in 65 foals (2010-2015)

OBJECTIVE

To report the short- and long-term outcomes of surgical management of umbilical infection in foals.

STUDY DESIGN

Retrospective case series.

ANIMALS

Foals (n = 65).

METHODS

Medical records (2010-2015) of foals up to 1 month of age, surgically treated for an umbilical infection were reviewed. Short-term (at the time of discharge from hospital) and long-term (1 year after surgery) survival rates were obtained. Clinical variables influencing survival were assessed. Chi-square or Fisher's exact test were used to evaluate the relationship between the data retrieved and outcome. P ≤ .05 was considered statistically significant.

RESULTS

Sixty-five foals were included in the study, representing 17.2% of all foals admitted to the hospital. Fifty foals were discharged from hospital (77%) and 43 foals (66%) were alive 1 year after surgery. Lower long-term survival rates were associated with: younger age at presentation, septic joints, multiple pathologies, higher creatinine level, higher heart rate, umbilical infection diagnosed at the hospital rather than prior to referral, prolonged hospitalization, longer period between arrival and surgery, and postoperative complications. The most common surgical findings were urachal enlargement followed by right arterial enlargement.

CONCLUSION

Younger foals with worse systemic condition and concurrent disorders are at higher risk for treatment failure. Early diagnosis improves the outcome. Surgical treatment yields good results and should be considered upon diagnosis, after taking into account the clinical situation.

CLINICAL SIGNIFICANCE

Based on the results of this study, diagnosis and surgical management of umbilical infection in neonatal foals should be performed as early as possible, and a good outcome can be expected after surgery.

Not just a number: effect of age on fertility, pregnancy and offspring vigour in thoroughbred brood-mares

Advancing age can adversely affect a thoroughbred brood-mare's reproductive efficiency and influence the commercial and athletic potential of her progeny. Causes for the decline in fertility include decreased oocyte and embryo quality, anatomical defects and endometrial degeneration. In addition, evidence exists that as the age of a dam increases, her foals will be at increased risk of morbidity and mortality during the neonatal period. Health issues can have lasting and deleterious effects on surviving foals, including decreased sale value and reduced athletic performance. The purpose of this review is to evaluate the association between mare age, fertility and offspring vigour in thoroughbred horses.

Factors associated with outcome and gradual improvement in survival over time in 1065 equine neonates admitted to an intensive care unit

REASONS FOR PERFORMING STUDY

There is a paucity of information regarding the association between common disorders and outcome over time in a large population of ill equine neonates.

OBJECTIVES

To describe the relative frequency of neonatal disorders in a large population of foals admitted to a neonatal intensive care unit, to determine the disorders and factors associated with nonsurvival and determine if the outcome of ill neonatal foals has improved over time.

STUDY DESIGN

Retrospective study.

METHODS

Cases were selected from equine neonatal (≤14 days of age) admissions between 1982 and 2008. Multivariable logistic regression was used to identify the disorders, clinical parameters and laboratory variables associated with nonsurvival or natural death and assess survival over time after accounting for potential confounding variables.

RESULTS

A total of 1065 foals were included in the study. Overall, 775 of 1065 (72.8%) foals survived to be discharged from the hospital and 290 (27.2%) foals were nonsurvivors. Age at admission, sepsis score, proportion of foals with positive blood cultures and proportion of survivors were significantly different (P<0.001) between primary disease categories. Variables retained in the multivariable model for nonsurvival included positive blood culture, neutrophils <2.28 × 10⁹ /l, temperature ≤37.6°C, bicarbonate, PCO₂ , presence of infectious orthopaedic disorders and sepsis score. The adjusted odds of survival for foals admitted in the 2000s were approximately 3.4 (95% CI = 1.9-6.0, P<0.001) times higher than that of foals admitted in the 1980s.

CONCLUSIONS

Primary disorders, sepsis, temperature, acid base status and neutropenia are the main factors that affect outcome in this population of equine neonates. The survival of foals admitted to a neonatal intensive care unit has increased dramatically over a 26 year period.

Retrospective evaluation of blood culture isolates and sepsis survival rate in foals in the Czech Republic: 50 cases (2011-2013)

OBJECTIVE

To identify the specific pathogens causing sepsis in hospitalized foals in the Czech Republic and identify important factors associated with their survival.

DESIGN

A retrospective study from 2011 to 2013.

SETTING

University veterinary teaching hospital.

ANIMALS

Fifty compromised foals.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Blood was aseptically collected for bacterial culture from compromised foals. The foals were classified as septic according to a positive blood culture result or sepsis score ≥11. Blood cultures were positive in 44% of the foals. In these positive cultures, 27.3% had only Gram-positive (G+) bacteria and 54.5% had only Gram-negative (G-) bacteria. A mixed bacterial population was presented in 18.2% of the positive cultures. Thirty-six foals were classified as septic on the basis of positive blood culture or a sepsis score ≥11. In the group of foals that did not survive, there were significantly more foals with low levels of immunoglobulin G (IgG) than foals with normal levels of IgG (P < 0.0001). We also found a significant difference in the proportion of foals with low levels of IgG and positive blood cultures when compared to negative blood cultures. Twenty-six of the 50 foals were discharged from the hospital. Survival was significantly lower in foals with a diagnosis of sepsis than in foals without sepsis. There was no statistically significant difference between foals that died as a result of infection caused by G- or G+ pathogens. There was no difference in the proportion of survivors that did or did not receive antimicrobials prior to admission.

CONCLUSIONS

In our study, we confirmed the increasing trend for G+ bacteria in blood cultures but G- still predominate. The percentage of nonsurviving septic foals was high.

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.

Clinical findings and survival in 56 sick neonatal New World camelids

BACKGROUND

Information pertaining to clinical presentation and outcome of neonatal New World camelids (NWC) is limited when compared to calves and foals.

HYPOTHESIS

Values of variables at admission and subsequent treatment would predict survival in sick neonatal NWC.

ANIMALS

Fifty-six client-owned sick neonatal NWC presented over a 10-year period to the Purdue University Veterinary Teaching Hospital.

METHODS

A retrospective study was performed. Inclusion criteria were NWC less than 30 days of age with complete medical records that presented between 2000 and 2010.

RESULTS

The median age at presentation was 1 day (range 1-20). The most common diagnoses were systemic inflammatory response syndrome (50%), congenital defects (41%), ophthalmic lesions (21%), sepsis (16%), and gastrointestinal diseases (16%). Sixty-six percent of NWC survived to discharge. Clinicopathologic findings on admission were variable and not specific for disorders. Factors associated with survival were absence of choanal atresia (P = .001, OR: 55.9 [2.5-1,232]), administration of llama plasma (P = .013, OR: 4.9 [1.4-17.7]), and antimicrobial treatment with trimethoprim-sulfamethoxazole (TMS) (P = .016, OR: 6.5 [1.3-32.2]).

CONCLUSIONS AND CLINICAL IMPORTANCE

The use of antibiotics, particularly TMS, and llama plasma are recommended in sick neonatal NWC. Results from this study could contribute toward defining a NWC-specific sepsis scoring system.

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.

Re-evaluation of the sepsis score in equine neonates

REASONS FOR PERFORMING STUDY

The modified sepsis scoring system provides a method to identify sepsis in foals early in the disease process, but inconsistent results have been obtained from its clinical application in previous studies.

OBJECTIVES

To evaluate the sensitivity and specificity of the modified sepsis score in a larger population of foals. A secondary objective was to identify factors associated with sepsis.

STUDY DESIGN

Retrospective cohort study.

METHODS

Records were retrospectively analysed for neonatal admissions to the University of Florida Large Animal Hospital from 1982 to 2008. Backwards stepwise multivariable logistic regression was used to evaluate objective clinical factors associated with sepsis. Receiver operating chararacteristic ROC curve analysis was performed on the modified sepsis score and used to determine an optimal cut point.

RESULTS

A total of 1065 foals were included in the study. The modified sepsis score had a sensitivity of 56.4% and specificity of 73.4% for the originally suggested cut point (>11). Receiver operating chararacteristic analysis revealed an optimal cut point of >7 (sensitivity 84.4%, specificity 41.8%). The modified sepsis score performed better than the generated regression model which included age, creatinine, lymphocytes, potassium and IgG>8 g/l (P = 0.026). Diagnostic performance of the modified sepsis score did not change significantly over time.

CONCLUSIONS

Sensitivity and specificity of the modified sepsis score were not as high as previously documented, but the score still outperformed a regression model derived from objective clinical data. The Summary is available in Chinese - see Supporting information.