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Background: The hypothalamic-pituitary-adrenal axis regulates the response to sepsis-associated stress. Relative adrenal insufficiency or adrenocorticotropic hormone (ACTH):cortisol imbalance, defined as a poor cortisol response to administration of ACTH, is common and associated with death in hospitalized foals. However, information on other adrenal steroid response to ACTH stimulation in sick foals is minimal., Objective: To investigate the response of multiple adrenocortical steroids to administration of ACTH in foals., Animals: Hospitalized (n = 34) and healthy (n = 13) foals., Methods: In this prospective study, hospitalized foals were categorized into 2 groups using cluster analysis based on adrenal steroids response to ACTH stimulation: Cluster 1 (n = 11) and Cluster 2 (n = 23). After baseline blood sample collection, foals received 10 μg of ACTH with additional samples collected at 30 and 90 minutes after ACTH. Steroid and ACTH concentrations were determined by immunoassays. The area under the curve (AUC) and Delta 0-30 were calculated for each hormone., Results: The AUC for cortisol, aldosterone, androstenedione, pregnenolone, 17α-OH-progesterone, and progesterone were higher in critically ill (Cluster 1) compared to healthy foals (P < .01). Delta 0-30 for cortisol and 17α-OH-progesterone was lower in Cluster 1 (24%, 26.7%) and Cluster 2 (16%, 11.2%) compared to healthy foals (125%, 71%), respectively (P < .05). Foals that died had increased AUC for endogenous ACTH (269 versus 76.4 pg/mL/h, P < .05) accompanied by a low AUC for cortisol (5.5 versus 15.5 μg/dL/h, P < .05), suggesting adrenocortical dysfunction., Conclusion and Clinical Importance: The 17α-OH-progesterone response to administration of ACTH was a good predictor of disease severity and death in hospitalized foals., (© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

The objective of this study was to determine the prevalence of Rhodococcus equi strains resistant to macrolides and rifampin over time in clinical samples from foals submitted to diagnostic laboratories in central Kentucky. We performed a retrospective observational study of all clinical samples from foals that were submitted to veterinary diagnostic laboratories in Kentucky between January 1995 and December 2017. Samples were included if the R. equi bacterium was cultured and tested for in vitro susceptibility to erythromycin or rifampin. In vitro susceptibility testing to erythromycin was available for 2,169 isolates of R. equi , while susceptibility testing to both erythromycin and rifampin was available for 1,681 isolates. Rifampin resistance was first detected in 2000, and erythromycin resistance was first detected in 2004. Between 1995 and 2006, the proportion of resistant isolates of R. equi was 0.7% for erythromycin and 2.3% for rifampin. There was a significant ( P < 0.001) increase in the proportion of resistant R. equi between 2007 and 2017, with 13.6% of isolates being resistant to erythromycin and 16.1% being resistant to rifampin. Between 2007 and 2017, isolates of R. equi resistant to erythromycin or rifampin were significantly less likely to be isolated from feces than from the respiratory tract, other soft tissues, or musculoskeletal infections. The considerable increase in the prevalence of isolates of R. equi resistant to macrolides and rifampin since 2007 is of concern for both human and animal health., (Copyright © 2018 American Society for Microbiology.)

Background: The original equine sepsis score provided a method of identifying foals with sepsis. New variables associated with sepsis have been evaluated, but the sepsis score has not been updated., Objectives: To evaluate the sensitivity and specificity of 2 updated sepsis scores and the systemic inflammatory response syndrome (SIRS) criteria in regard to detecting sepsis in foals., Animals: Two-hundred and seventy-three ill foals and 25 healthy control foals., Methods: Historical, physical examination, and clinicopathologic findings were used to calculate the original sepsis score and 2 updated sepsis scores. SIRS criteria were also evaluated. Sepsis scores and positive SIRS scores were statistically compared to foals with sepsis., Results: One-hundred and twenty-six foals were septic and 147 sick-nonseptic. The original and updated sepsis scores were significantly higher in septic foals as compared to sick-nonseptic and healthy foals. The sensitivity and specificity of the updated sepsis scores to predict sepsis were not significantly better than those of the original sepsis score. One-hundred and twenty-seven of 273 (46.5%) foals met the original SIRS criteria and 88/273 (32%) foals met the equine neonatal SIRS criteria. The original SIRS criteria had similar sensitivity and specificity for predicting sepsis as did the 3 sepsis scores in our study., Conclusions and Clinical Importance: The updated sepsis scores did not provide improved ability in predicting sepsis. Fulfilling the original SIRS criteria provided similar sensitivity and specificity in predicting sepsis as the modified sepsis score and might serve as a diagnostic aid in identifying foals at risk for sepsis., (Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Hypothalamic-pituitary-adrenal axis (HPAA) dysfunction has been associated with sepsis and mortality in foals. Most studies have focused on cortisol, while other steroids have not been investigated. The objectives of this study were to characterise the adrenal steroid and steroid precursor response to disease and to determine their association with the HPAA response to illness, disease severity, and mortality in hospitalised foals. All foals (n=326) were classified by two scoring systems into three categories: based on the sepsis score (septic, sick non-septic [SNS] and healthy) and the foal survival score (Group 1: 3-18%; Group 2: 38-62%; Group 3: 82-97% likelihood of survival). Blood concentrations of adrenocorticotropic hormone (ACTH) and steroids were determined by immunoassays. ACTH-cortisol imbalance (ACI) was defined as a high ACTH/cortisol ratio. Septic foals had higher ACTH, cortisol, progesterone, 17α-OH-progesterone, pregnenolone, and androstenedione concentrations as well as higher ACTH/cortisol, ACTH/progesterone, ACTH/aldosterone, and ACTH/DHEAS ratios than SNS and healthy foals (P<0.01). Foals with DHEAS of 0.4-5.4ng/mL were more likely to have ACI (OR=2.5). Foals in Group 1 had higher ACTH, aldosterone, progesterone, and cortisol concentrations as well as ACTH/cortisol, ACTH/progesterone, and ACTH/DHEAS ratios than foals in Groups 2 and 3 (P<0.01). High progesterone concentrations were associated with non-survival and the cutoff value below which survival could be predicted was 23.5ng/mL, with 75% sensitivity and 72% specificity. In addition to cortisol, the response to the stress of illness in foals is characterised by the release of multiple adrenal steroids. DHEAS and progesterone were good predictors of HPAA dysfunction and outcome in hospitalised foals., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Reasons for Performing Study: Critically ill foals often present to veterinary hospitals with impaired organ perfusion which can be demonstrated by increased blood L-lactate concentrations. As a compensatory mechanism to low blood pressure and electrolyte abnormalities, aldosterone and arginine vasopressin (AVP) are released to restore organ perfusion and function. Several studies have investigated the ability of blood L-lactate concentrations to predict severity of disease and outcome in critically ill human patients, adult horses and foals. However, information on the aldosterone and AVP response to hypoperfusion and its association with L-lactate concentrations in neonatal foals is limited., Objectives: To determine the association between clinical hypoperfusion and endocrine markers of reduced tissue perfusion in normo- and hypoperfused foals., Study Design: Prospective, multicentre, cross-sectional observational study., Methods: Blood samples were collected on admission from 72 clinically hypoperfused, 110 normoperfused (73 hospitalised and 37 healthy) foals of ≤4 days of age. Foals were considered clinically hypoperfused if they had L-lactate concentrations ≥2.5 mmol/l and one of the 3 following findings: heart rate >120 beats/min, packed cell volume (PCV) >0.44 l/l or azotaemia (increased creatinine and blood urea nitrogen [BUN]). Blood concentrations of aldosterone and AVP were determined by radioimmunoassays., Results: Aldosterone, AVP, creatinine and BUN concentrations and heart rate, PCV and blood osmolality were higher in clinically hypoperfused compared with normoperfused foals (P<0.05). Risk of hypoperfusion increased with the presence of hypothermic extremities (OR = 5.26) and with each one unit increase in albumin concentrations (OR = 3.5) (P<0.05). The proposed admission L-lactate cut-off value above which nonsurvival could be reliably predicted in hospitalised foals was 10.6 mmol/l with 82% of sensitivity and 74% of specificity., Conclusions: Hyperaldosteronaemia and hypervasopressinaemia as well as hypothermic extremities and increased albumin concentrations are potent predictors of hypoperfusion in hospitalised foals., (© 2015 EVJ Ltd.)

Background: The renin-angiotensin-aldosterone system (RAAS) and hypothalamic-pituitary-adrenal axis (HPAA) and their interactions during illness and hypoperfusion are important to maintain organ function. HPAA dysfunction and relative adrenal insufficiency (RAI) are common in septic foals. Information is lacking on the RAAS and mineralocorticoid response in the context of RAI in newborn sick foals., Objectives/hypothesis: To investigate the RAAS, as well as HPAA factors that interact with the RAAS, in hospitalized foals, and to determine their association with clinical findings. We hypothesized that critical illness in newborn foals results in RAAS activation, and that inappropriately low aldosterone concentrations are part of the RAI syndrome of critically ill foals., Animals: A total of 167 foals ≤3 days of age: 133 hospitalized (74 septic, 59 sick nonseptic) and 34 healthy foals., Methods: Prospective, multicenter, cross-sectional study. Blood samples were collected on admission. Plasma renin activity (PRA) and angiotensin-II (ANG-II), aldosterone, ACTH, and cortisol concentrations were measured in all foals., Results: ANG-II, aldosterone, ACTH, and cortisol concentrations as well as ACTH/aldosterone and ACTH/cortisol ratios were higher in septic foals compared with healthy foals (P < .05). No difference in PRA between groups was found. High serum potassium and low serum chloride concentrations were associated with hyperaldosteronemia in septic foals., Conclusions and Clinical Importance: RAAS activation in critically ill foals is characterized by increased ANG-II and aldosterone concentrations. Inappropriately low cortisol and aldosterone concentrations defined as high ACTH/cortisol and ACTH/aldosterone ratios in septic foals suggest that RAI is not restricted to the zona fasciculata in critically ill newborn foals., (Copyright © 2013 by the American College of Veterinary Internal Medicine.)

Reasons for Performing Study: Although antimicrobial-associated diarrhoea (AAD) is the most frequently observed adverse effect of antimicrobial therapy in horses, few multicentred studies on the prevalence of AAD have been performed., Objectives: To determine the prevalence of AAD in horses that developed diarrhoea after antimicrobial treatment for nondiarrhoeic conditions and identify the antimicrobials used., Methods: The 2009 database of 3 referral hospitals was searched to identify nonhospitalised horses (weanling age or older) treated with antimicrobials for nongastrointestinal conditions. Horses with these criteria that presented with diarrhoea during 2009 were included in the study. Additional information, including antimicrobial administered and results of faecal pathogen testing, was gathered on each hospitalised case., Results: Of the 5251 horses treated with antimicrobials for nongastrointestinal signs, 32 were diagnosed with probable AAD, a prevalence of 0.6% (95% confidence interval: 0.43-0.86%). The AAD-diagnosed horses had an 18.8% (6/32) mortality rate. Horses with AAD had been treated for an average of 4.2 days. The most frequently used antimicrobials in horses with AAD were gentamicin in combination with penicillin (n = 7), enrofloxacin (n = 7) and doxycycline (n = 4). Clostridium difficile was identified in faecal samples from 4 horses, 2 of which died and Salmonella from 3 horses., Conclusions: Results indicated that the prevalence of AAD is low. Any antimicrobial class commonly used in equine practice is a potential cause of equine AAD. Other risk factors, such as opportunistic enteropathogens, may play a part in the development of diarrhoea secondary to antimicrobial usage., Potential Relevance: Although the risk of equine AAD is low, this sequela of antimicrobial treatment is possible especially when opportunistic enteropathogens or other risk factors are present. Because drugs from any antimicrobial class can be potentially involved in AAD, clinicians have additional incentive to ensure the judicious use of antimicrobial agents., (© 2012 EVJ Ltd.)

Reasons for Performing Study: Dysphagia due to pharyngeal dysfunction occurs in human neonates and is associated with prematurity and hypoxic episodes. This syndrome probably occurs in neonatal foals but has not been reported., Objectives: The objectives of this study were to describe 1) a series of neonatal foals with dysphagia due to pharyngeal dysfunction; 2) the progression, treatment and resolution of the dysphagia; 3) the comorbidities; and 4) the prognosis for life and athleticism for affected foals., Methods: Records from 3 referral equine hospitals were reviewed from neonatal foals with dysphagia of pharyngeal origin. Inclusion criteria were a normal to strong suckle, dysphagia evidenced by milk at the nostrils after nursing the dam, and endoscopic examination of the airway. Foals with mechanical reasons for dysphagia, botulism or hyperkalaemic periodic paralysis were not included., Results: Sixteen neonatal foals qualified for the study. Eight (50%) were premature and/or diagnosed with hypoxic ischaemic encephalopathy. Twelve (75%) had aspiration pneumonia. Fifteen foals were discharged alive from the hospital, nursing the mare with no evidence of dysphagia (n = 14), or mild dysphagia (n = 1), a mean +/- s.d. of 7 +/- 6 days (median = 6.3 days, range 0-22 days) after hospital admission. One foal was subjectedto euthanasia in hospital. Follow-up nformation was available for 14 animals. Thirteen of 16 (81%) were alive and included one yearling and 12 horses >2 years old. Seven of the 14 (50%) were racing, training or in work, and 6 horses were pets, breeding animals or had unknown athletic status. Two had laryngeal deficits. One foal was subjected to euthanasia within weeks of discharge from the hospital due to aspiration pneumonia., Conclusion: Dysphagia related to pharyngeal dysfunction occurs in equine neonates and can resolve, but may require days to weeks of supportive care. Prognosis for life is favourable and for athleticism fair.

Objectives: To (1) determine the occurrence of spurious hypercreatininemia in a population of hospitalized foals<2 days old, (2) assess the resolution of the hypercreatininemia, and (3) determine its association with survival in these foals., Design: Retrospective case series., Setting: 2 Referral hospitals., Animals: Foals<2 days old with an admission creatinine>442 micromol/L (>5.0 mg/dL) from 2 referral hospitals., Interventions: None., Measurements and Main Results: The medical records of 33 foals were reviewed. Twenty-eight had spurious hypercreatininemia and 5 had acute renal failure. Admission creatinine was not significantly different between the 2 groups (mean [standard deviation]). The creatinine was 1,202 micromol/L (663 micromol/L) (13.6 mg/dL [7.5 mg/dL]) versus 1,185 micromol/L (787 micromol/L) (13.4 mg/dL [8.9 mg/d]) (P=0.96) in each group, respectively, though BUN at the time of hospital admission was significantly higher for acute renal failure foals (P=0.009). In the spurious group, serum creatinine at admission decreased to 504 micromol/L (380 micromol/L) (5.7 mg/dL [4.3 mg/dL]) by 24 hours, and to 159 micromol/L (80 micromol/L) (1.8 mg/dL [0.9 mg/dL]) at 48 hours, and to 115 micromol/L (44 micromol/L) (1.3 mg/dL [0.5 mg/dL]) at 72 hours. Twenty-three of 28 foals with spurious hypercreatininemia survived to hospital discharge and there was no difference in mean admission creatinine between survivors (1176 micromol/L [628 micromol/L]) (13.3 mg/dL [7.1 mg/dL]) and nonsurvivors (1308 micromol/L [857 micromol/L]) (14.8 mg/dL [9.7 mg/dL]) (P=0.67). Twenty of 28 foals had clinical signs suggestive of neonatal encephalopathy., Conclusion: Creatinine decreased by >50% within the initial 24 hours of standard neonatal therapy and was within the reference interval in all but 1 foal within 72 hours of hospitalization. The diagnosis of neonatal encephalopathy was common in these foals.

Objective: To report short- and long-term survival and factors affecting outcome of foals after surgical correction of gastric outflow obstruction., Study Design: Case series., Animals: Foals (n=40) aged 5-180 days., Methods: Clinical signs, laboratory data, diagnostic imaging, surgical findings, surgical procedures, medical treatment, and necropsy findings were retrieved from medical records. Outcome was obtained by reviewing performance, sales, and produce records or by telephone conversations with the owners., Results: Gastric outflow obstruction was treated by gastroduodenostomy or by gastrojejunostomy with or without jejunojejunostomy. Long-term follow-up was available for 36 of 39 foals that survived to hospital discharge; 25 (69%) survived >2 years. All 8 foals with pyloric obstruction survived >2 years, whereas only 11 of 21 (52%) foals with duodenal obstruction survived >2 years. Six of 8 foals with obstruction of the duodenum and pylorus survived >2 years. Obstruction of the duodenum, adhesions to the duodenum, and postoperative ileus were significantly associated with decreased long-term survival., Conclusions: Long-term outcome after gastric bypass procedures was substantially improved compared with previous reports. Factors that may have contributed to improved survival include better case selection and performing the gastrojejunostomy with the jejunum aligned from left to right., Clinical Relevance: The prognosis for long-term survival after surgical bypass of pyloric obstruction is excellent. The overall prognosis for long-term survival after surgical bypass of duodenal obstruction is fair but should be considered guarded in those with pre-existing duodenal adhesions.

Objective: To identify risk factors for equine protozoal myeloencephalitis (EPM) among horses examined at 11 equine referral hospitals., Design: Case-control study., Animals: 183 horses with EPM, 297 horses with neurologic disease other than EPM (neurologic controls), and 168 horses with non-neurologic diseases (non-neurologic controls) examined at 11 equine referral hospitals in the United States., Procedures: A study data form was completed for all horses. Data were compared between the case group and each of the control groups by means of bivariate and multivariate polytomous logistic regression., Results: Relative to neurologic control horses, case horses were more likely to be > or = 2 years old and to have a history of cats residing on the premises. Relative to non-neurologic control horses, case horses were more likely to be used for racing or Western performance., Conclusions and Clinical Relevance: Results indicated that cats may play a role in the natural epidemiology of EPM, that the disease is less common among horses < 2 years of age relative to other neurologic diseases, and that horses used for particular types of competition may have an increased risk of developing EPM.

Lower respiratory tract infection is common in weanling- and suckling-aged animals. Increased susceptibility to disease in this age group can result from a delay in the establishment of a competent immune system and environmental factors, such as overcrowding, shipping, and sales. S zooepidemicus and R equi are the two most common bacterial isolates. S equi is primarily a disease of the lymph nodes and upper respiratory tract. Viral agents can compromise the natural defense mechanisms of the respiratory tract, resulting in secondary bacterial infections. The acute respiratory distress syndrome is one of unknown etiology and high mortality.